# Patent

## Title
Flash electronic disk with RAID controller

## Abstract

In an embodiment of the invention, a method is presented to operationally integrate one or more RAID control mechanisms into a flash electronic disk controller. The method includes incorporating one or more RAID features into a flash electronic disk by adding one or more RAID components in a flash controller, wherein the flash electronic disk includes a RAID control module to control the one or more RAID components; receiving a read or write operation command at a flash controller from a host; translating the read or write operation command into a command format understood by one or more flash controllers; translating the command format into an instruction format understood by one or more flash memory devices; and accessing one or more memory locations in the one or more flash memory devices according to the instruction format to perform a read or write operation for the host.

## Background
CROSS-REFERENCE(S) TO RELATED APPLICATIONS
This application claims the benefit of and priority to U.S. Provisional Application 61/801,111, filed 15 Mar. 2013. This U.S. Provisional Application 61/801,111 is hereby fully incorporated herein by reference.
This application relates to U.S. Utility application Ser. No. 14/217,316, “Flash Array RAID in Flash Electronic Disks” which is hereby fully incorporated herein by reference and U.S. Utility application Ser. No. 14/217,291, “Direct Memory Access Controller with RAID Hardware Assist” which is hereby fully incorporated herein by reference.


FIELD
Embodiments of the invention relate generally to computer systems and more particularly to Flash Electronic Disk with RAID Controller.
DESCRIPTION OF RELATED ART
Over the last few years, the storage systems industry has witnessed an increasing trend in shifting data storage from mechanical hard disk drives (HDD) to solid state devices (SSD), the Flash Electronic Disk being one of them. This is brought about by a number of advantages in using SSD's over HDD's, the most notable ones are increased data accessing speed, increased reliability in terms of data integrity and physical stress, and prolonged wear and tear.
The increase in data accessing speed opened up a wide range of applications that were used to be shelved because of the memory-access bottleneck. With the coming of Flash Electronic Disks, data-intensive applications now have a chance to come into reality. The absence of rotating mechanical disks in Flash Electronic Disks allowed more memory intensive applications that are physically demanding, such as military applications, shock prone environments and the like, to come into shape.
Trends in the market today point to an increasing demand for SSDs because of its fast memory access speeds. Memory intensive applications, such as database interfaces, are slowly coming into shape as the memory access bottleneck is loosened up. In the advent of memory intensive applications, it is imperative that systems should have reliable and stable data integrity measures. The most reliable data integrity system to date is the RAID system, which has been applied extensively to many computer systems using HDDs. The RAID system uses a simple architecture where data is striped or mirrored to a number of disks. All possible implementations of redundancy are already considered in its many configurations. These principles can also be applied to flash electronic disks to boost data integrity.
Conventional RAID systems prefer implementing RAID Controllers as a separate hardware entity. This is because RAID controls are computations-extensive, that when implemented in firmware, a big chunk of the CPU resource is eaten up. This invention helps to unload the firmware of a computational burden, as this invention implements RAID in hardware, but it takes it a step further. There will be no separate hardware entity for the RAID controls as it will all be integrated into the disk itself, producing a Flash Electronic Disk that is also a RAID Controller at the same time.
SUMMARY
The Flash Electronic Disks are known for its stable and reliable performance over traditional HDDs due to the absence of mechanical components. An embodiment of this invention aims to fortify the existing data integrity badge of Flash Electronic Disks by integrating RAID measures into the disk. Flash Electronic Disks in a RAID configuration would be by far, the most reliable storage system to date.
An embodiment of this invention presents a method and system for implementing RAID for Flash Electronic Disks. The invention integrates RAID control mechanisms into the Flash Electronic Disk controllers, eliminating the need for a separate RAID controller hardware, with minimal firmware intervention. The system and method uses the principles of RAID in addressing the issues brought about by physical disk crashes. The invention merges the benefits of using Flash Electronic Disks and the capabilities of RAID in data integrity, such as hot pluggable disks, into a Flash Electronic Disk. The system and method supports all RAID levels via configurable RAID controller. The system and method also provides possible RAID configurations for the disks over generic IO Interfaces.
In another embodiment of the invention, a method and system for implementing a Flash Electronic Disk with support for Redundant Array of Inexpensive Disks (RAID) system is presented. The method and system include a RAID Control Module that interprets RAID commands from any Host, an Exclusive-Or (XOR) Engine for RAID commands with parity computations, a RAID Cache for temporary storage during calculations, and possible RAID configurations for the Flash Electronic Disks via generic IO interfaces such as SATA, SCSI or PCI Express (PCIe). The invention presents a Flash Electronic Disk that is capable of executing RAID Master and Slave functions over conventional links without the need for a separate RAID Controller hardware and without extensive use of firmware processing.
A key idea of embodiments of this invention lies on having Flash Electronic Disks that offer data integrity capabilities of RAID in highly flexible configurations, without sacrificing the high memory accessing speed of Flash Electronic Disks.



BRIEF DESCRIPTION OF DRAWINGS
So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the present invention may admit to other equally effective embodiments.
FIG. 1 shows a typical prior art Flash Electronic Disk System.
FIG. 2 shows a typical prior art RAID system and its components.
FIG. 3 illustrates a write operation implementation for a typical prior art RAID-5 system.
FIG. 4 illustrates a read operation implementation for a typical prior art RAID-5 system.
FIG. 5 illustrates a read-modify-write operation implementation for a typical prior art RAID-5 system.
FIG. 6 illustrates the modified Flash Electronic Disk Architecture according to an embodiment of the present invention.
FIG. 7 shows a RAID system consisting of ordinary disks and the Flash Electronic Disk according to an embodiment of the present invention.
FIG. 8 is the write operation implementation in a Flash Electronic Disk taking a master role in a RAID-5 system according to an embodiment of the present invention.
FIG. 9 illustrates how the Flash Electronic Disk performs the flushing process according to an embodiment of the present invention.
FIG. 10 is the read operation implementation in a Flash Electronic Disk taking a master role in a RAID-5 system according to an embodiment of the present invention.
FIG. 11 is the read-modify-write operation implementation in a Flash Electronic Disk taking a master role in a RAID-5 system according to an embodiment of the present invention.
FIG. 12 is the write operation implementation in a Flash Electronic Disk taking dual roles in a RAID-5 system according to an embodiment of the present invention.
FIG. 13 is the read operation implementation in a Flash Electronic Disk taking dual roles in a RAID-5 system according to an embodiment of the present invention.
FIG. 14 is the read-modify-write operation implementation in a Flash Electronic Disk taking dual roles in a RAID-5 system according to an embodiment of the present invention.
FIG. 15 is a possible configuration of four Flash Electronic Disks in a RAID System according to an embodiment of the present invention.
FIG. 16 summarizes the multi-RAID configuration of multiple Flash Electronic Disks according to an embodiment of the present invention.
FIG. 17 illustrates a method to operationally integrate one or more RAID control mechanisms into a flash electronic disk controller, in accordance with one embodiment of the invention.



DETAILED DESCRIPTION
In the following detailed description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the various embodiments of the present invention. Those of ordinary skill in the art will realize that these various embodiments of the present invention are illustrative only and are not intended to be limiting in any way. Other embodiments of the present invention will readily suggest themselves to such skilled persons having the benefit of this disclosure.
In addition, for clarity purposes, not all of the routine features of the embodiments described herein are shown or described. One of ordinary skill in the art would readily appreciate that in the development of any such actual implementation, numerous implementation-specific decisions may be required to achieve specific design objectives. These design objectives will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine engineering undertaking for those of ordinary skill in the art having the benefit of this disclosure. The various embodiments disclosed herein are not intended to limit the scope and spirit of the herein disclosure.
Preferred embodiments for carrying out the principles of the present invention are described herein with reference to the drawings. However, the present invention is not limited to the specifically described and illustrated embodiments. A person skilled in the art will appreciate that many other embodiments are possible without deviating from the basic concept of the invention. Therefore, the principles of the present invention extend to any work that falls within the scope of the appended claims.
As used herein, the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.
FIG. 1 shows a typical prior art Flash Electronic Disk architecture. A Flash Electronic Disk 103 is composed mainly of Flash Memory Devices 104, linked to the Flash Controller 102 by a Flash Interconnect 101. The Flash Interconnect 101 handles the necessary data passing sequences between the Host 100 and the Flash Memory Devices. The Host 100 is typically a CPU of a computer system which sends out instructions to the disk via the IO Bus 105. The Flash Electronic Disk 103 mimics an ordinary HDD so that the Host 100 sees it as an ordinary storage device. The Host issues read and write commands to the Flash Electronic Disk as if it is just accessing an ordinary HDD. The Flash Controller 102 of the Flash Electronic Disk translates the instructions from the Host 100 into flash native commands which are understood by the plurality of Flash Memory Devices 104. FIG. 1 describes a typical storage device system, though in this case, the storage device uses flash memory devices instead of the conventional rotating mechanical disks.
FIG. 2 illustrates a typical prior art RAID system and its components. A RAID system has a RAID Controller 207 that manages a plurality of Slave Disks 205 and makes them appear as just one storage device to the Host 200. Host 200 is usually a computer CPU that sends out memory transfer instructions to the RAID system 201. In general, the RAID Controller handles all system-related activities such as communicating to the host, accessing the slave disks, maintaining system information, executing requested transfers and recovering from disk failures. A typical RAID system distributes its data across all the slave disks in a manner commonly referred to as data striping. By allowing more than one slave disk in the system, RAID allows for concurrent access by independent processes. RAID has 5 distinct levels/configurations for redundancy; some users though combine these configurations to produce hybrids that suit their purpose. Most RAID levels employ parity for redundancy, thus requiring the use of combinational logic to implement the equivalent of an Exclusive-OR (XOR) Engine 203, which is a processing element that performs parity calculations. The RAID Cache 206 is the temporary storage of data commonly used for RAID parity operations. The Mapping Table 202 is used by the RAID Controller 207 to determine which slave disk(s) are being referred to by the request. The Mapping Table 202 is used to translate the logical block addresses specified in the commands received from the Host 200 into addresses that point to the actual physical disk locations. The Mapping Table 202 is created based on the RAID system configuration. The plurality of Slave Disks 205 and the RAID Controller 207 are linked together via IO Bus 204, which could include any of the existing IO interfaces available today, such as SCSI, SATA, PCIe, or an equivalent interface.
FIG. 3 illustrates a write operation implementation for a typical prior art RAID-5 system. RAID-5 is one of the most common protection techniques against failed disks. This RAID configuration works by striping data and parity information across all the slave disks. In FIG. 3, Host 300 issues a write command 308 to the RAID Controller 307. The write data 309 is stored in the RAID Cache 306. The RAID Controller after referring to its Mapping Table 302 determines that the write data in the RAID Cache 306 should be striped across the plurality of slave disks 305. The RAID Controller issues an IO write command 310 to write data stripe 0 314 to Slave Disk 1 318, an IO write command 311 to write data stripe 1 315 to Slave Disk 2 319 and an IO write command 312 to write data stripe 2 316 to Slave Disk 3 320. The RAID Controller also generates the corresponding parity stripe 317 by XORing the data stripes. This parity stripe is written by the RAID Controller to Slave Disk N 321 by issuing another IO write command 313.
FIG. 4 illustrates a read operation implementation for a typical prior art RAID-5 system. Host 400 issues a read command 408 to the RAID Controller 407. The RAID Controller checks its Mapping Table 402 to determine from which slave disks 405 the data will come from. The RAID controller then issues an IO read command 414 to Slave Disk 1 410 to get data stripe 417, an IO read command 415 to Slave Disk 2 411 to get data stripe 418 and an IO read command 416 to Slave Disk 3 412 to get data stripe 419. These data stripes are stored and reconstructed in RAID Cache 406 before being sent to the Host 400 as the read data 409. In some cases, parity checking is performed during read operation in which case the parity stripe is read from the other disk and then XORed to all the data stripes read from the rest of the slave disks.
FIG. 5 illustrates a read-modify-write operation implementation for a typical prior art RAID-5 system. Read-modify-write occurs whenever the Host requests to write only a data stripe instead of the whole data block. Host 500 sends a write command 512 to the RAID Controller 507. The RAID Controller receives the write data 513 and stores it in the RAID Cache 506. After referring to the Mapping Table 502, the RAID Controller discovers that the write request involves a write of only a data stripe. The RAID Controller then issues an IO read command 514 to the Slave Disk 1 508 to read the old data stripe 515. The old data stripe 515 is XORed with the new data stripe stored in the RAID Cache 506 using the XOR Engine 503. The result of the XOR operation is temporarily stored in the RAID Cache 506. The new data stripe is still kept in the RAID Cache. The RAID Controller then issues an IO read command 518 to the Slave Disk N 511 to read the old parity 519. The old parity 519 is then XORed with the result of the previous XOR operation using the XOR Engine 503. The result of this XOR operation, the new parity, is again stored in the RAID Cache 506. After generating the new parity, the RAID Controller 507 issues an IO write command 516 to the Slave Disk 1 508 to write the new data stripe 517 from the RAID Cache 506. The RAID Controller also issues an IO write command 520 to the Slave Disk N 511 to write the new parity 521 from the RAID Cache 506. This completes the read-modify-write operation.
FIG. 6 illustrates the modified Flash Electronic Disk Architecture. In this invention, the RAID features are incorporated into the Flash Electronic Disk by adding the RAID components in the Flash Controller. The Flash Electronic Disk 608 is upgraded with the addition of the RAID Control Module 607, which handles the RAID capabilities of the invention. The RAID Control Module contains an XOR Engine 603 that is used during parity calculations, a RAID Cache 606 that serves as the temporary data storage during parity calculations and a Mapping Table 602 for address translation of the commands received from the Host 600.
In a computer system where RAID is needed, the Flash Electronic Disk in FIG. 6 becomes a ready RAID Controller eliminating the need for a separate hardware entity. The plurality of Flash Memory Devices 605 serves as the non-volatile cache of the RAID system. The Flash Memory Devices are used to store recently used information for the RAID system. The Flash Controller 601 partitions the Flash Memory Devices 605 into stripes and records the boundaries. The Flash Controller passes these boundaries to the RAID Control Module 607 for inter-disk striping of RAID. The use of these flash memory devices as cache significantly enhances the performance of the RAID system because they reduce frequent access to slower storage devices such as HDD.
The Flash Electronic Disk of FIG. 6 is also capable of handling master and slave roles in a RAID system. The plurality of Flash Memory Devices 605 may be used as a slave disk instead of a cache. The memory locations of the Flash Memory Devices are remapped on a new addressing scheme kept by the RAID Control Module 607 in its Mapping Table 602. In addition, it is possible to distribute the flash memory devices to a number of RAID systems. The Flash Electronic Disk can have one flash memory device assigned to its RAID Control Module 607, and the rest of its Flash Memory Devices 605 assigned to different RAID controllers in other RAID systems. This way, the Flash Electronic Disk 608 can participate in multiple RAID systems rather just one, and can also take dual roles depending on which RAID system it is in.
Furthermore, the plurality of Flash Memory Devices 605 can be configured as replacement disks or “hot spares”. The availability of replacement disks allows the RAID Control Module 607 to perform reconstruction. Reconstruction is a background process executed in the RAID system to regenerate the data from the failed disk. This process involves reading the data from the surviving slave disks for each stripe, calculating the parity of that data and then writing this value to the replacement disk. Reconstruction works both for data and parity disks since the XOR operation is commutative. The performance of the RAID system is degraded while a failed disk is being rebuilt. However, the RAID system continues to function in such a way that all data are still accessible by the Host including that from the failed disk.
FIG. 7 shows a RAID system consisting of ordinary disks and the Flash Electronic Disk according to an embodiment of the present invention. The Flash Electronic Disk is labeled as the “Master Disk” 704 to differentiate it from the Slave Disks 710 in the RAID system 711. The RAID Control Module 709 of the Master Disk 704 is configured to be the RAID Controller of the RAID system 711. The Master Disk 704 comprising of a Flash Controller 703 along with the Flash Interconnect 706 and the plurality of Flash Memory Devices 707, used as the system cache, communicates with the Slave Disks 710 through the one or more generic IO Bus 701, such as SCSI, SATA, PCIe, or an equivalent IO Bus. The slave disks of the RAID system 711 may be any other disk, HDD or SSD, as long as it can interface with the one or more IO Bus 701. The RAID Control Module 709 has its own XOR Engine 705 for parity calculations, a RAID Cache 708 for temporary storage of data and a Mapping Table 702 for translating the commands received for the RAID system.
FIG. 8 is the write operation implementation in a Flash Electronic Disk taking a master role in a RAID-5 system according to an embodiment of the present invention. The Master Disk 804 receives a write command 812 from the Host 800. The write data 813 is stored in the RAID Cache 808 of the RAID Control Module 809. The RAID Control Module after referring to its Mapping Table 802 determines that the write data in the RAID Cache 808 should be striped across the plurality of slave disks 810. The RAID Control Module translates the write request received from the Host 800 into multiple write accesses to the plurality of slave disks by converting the write data 813 into data stripes. The RAID Control Module also generates the corresponding parity stripe by XORing all the data stripes using its XOR Engine 805. This parity stripe is temporarily stored in the RAID Cache 808 along with the data stripes.
However, instead of accessing the slave disks frequently, the Master Disk 804 decides to first write the data stripes to its Flash Memory Devices 807. The Flash Memory Devices 807, being the system cache, contains the recently used information for the RAID system 811. The Flash Controller 803 therefore issues a flash write command 814 to write data stripe 0 818 to Flash Memory Device 1 822, a flash write command 815 to write data stripe 1 819 to Flash Memory Device 1 823 and a flash write command 816 to write data stripe 2 820 to Flash Memory Device 1 824. The Flash Controller also issues a flash write command 817 to write the parity stripe 821 to Flash Memory Device N 825. The data and parity stripes stored in the plurality of Flash Memory Devices 807 are periodically flushed to the plurality of Slave Disks 810.
FIG. 9 illustrates how the Flash Electronic Disk performs the flushing process according to an embodiment of the present invention. The plurality of the Flash Memory Devices 907 acts as the system cache of the RAID system 911. The contents of the Flash Memory Devices are regularly transferred to the Slave Disks. Flash Memory Device 1 920 is the cache of the Slave Disk 1 932. Flash Memory Device 2 921 is the cache of the Slave Disk 2 933. Flash Memory Device 3 922 is the cache of the Slave Disk 3 934. Flash Memory Device N 923 is the cache of the Slave Disk N 935. During flushing, the Flash Controller 903 issues a flash read command 912 to Flash Memory Device 1 920 to transfer the data block 0 916 to the RAID Cache 908. The Flash Controller then issues an IO write command 928 to Slave Disk 1 932 to transfer the same data block 0 924 from RAID Cache 908 to Slave Disk 1 932. In the same way, the Flash Controller 903 issues a flash read command 913 to Flash Memory Device 2 921 to transfer the data block 1 917 to the RAID Cache 908. The Flash Controller then issues an IO write command 929 to Slave Disk 2 933 to transfer the same data block 1 925 from RAID Cache 908 to Slave Disk 2 933. For Flash Memory Device 3 922, the Flash Controller 903 issues a flash read command 914 to Flash Memory Device 3 922 to transfer the data block 2 918 to the RAID Cache 908. The Flash Controller then issues an IO write command 930 to Slave Disk 3 934 to transfer the same data block 2 926 from RAID Cache 908 to Slave Disk 3 934. And lastly for Flash Memory Device N 923, the Flash Controller 903 issues a flash read command 915 to Flash Memory Device N 923 to transfer the data block N-1 919 to the RAID Cache 908. The Flash Controller then issues an IO write command 931 to Slave Disk N 935 to transfer the same data block N-1 927 from RAID Cache 908 to Slave Disk N 935.
FIG. 10 is the read operation implementation in a Flash Electronic Disk taking a master role in a RAID-5 system according to an embodiment of the present invention. Host 1000 issues a read command 1012 to the Master Disk 1004. The RAID Control Module 1009 determines that the requested data is striped across the plurality of slave disks 1010. The RAID Control Module translates the read request received from the Host 1000 into multiple read accesses to the plurality of slave disks by reading the corresponding data stripes. The RAID Control Module 1009 of the Master Disk checks its Mapping Table 1002 to determine from which slave disks 1010 the data stripes will come from.
However, instead of accessing the slave disks frequently, the Master Disk 1004 in one embodiment can decide to read the data stripes from its Flash Memory Devices 1007. The Flash Memory Devices 1007, being the system cache, contains the recently accessed information for the RAID system 1011. The Flash Controller 1003 therefore issues a flash read command 1014 to Flash Memory Device 1 1020 to get data stripe 1017, a flash read command 1015 to Flash Memory Device 2 1021 to get data stripe 1018 and a flash read command 1016 to Flash Memory Device 3 1022 to get data stripe 1019. These data stripes are stored and reconstructed in RAID Cache 1008 before being sent to the Host 1000 as the read data 1013.
FIG. 11 is the read-modify-write operation implementation in a Flash Electronic Disk taking a master role in a RAID-5 system according to an embodiment of the present invention. Host 1100 sends a write command 1112 to the Master Disk 1104. The RAID Control Module 1109 of the Master Disk receives the write data 1113 and stores it in the RAID Cache 1108. After referring to the Mapping Table 1102, the RAID Control Module discovers that the write request involves a write of only a data stripe. A write of only a data stripe involves a read-modify-write operation. The RAID Control Module first checks from which slave disks will the old data stripe and old parity stripe come from. The RAID Control Module determines that the old data stripe should come from Slave Disk 1 and the old parity stripe should come from Slave Disk N.
However, instead of accessing the slave disks frequently, the Master Disk 1104 decides to read these stripes from its Flash Memory Devices 1107. The Flash Memory Devices 1107, being the system cache, contains the recently accessed information for the RAID system 1111. The Flash Controller 1103 therefore issues a flash read command 1114 to the Flash Memory Device 1 1122 to read the old data stripe 1118. The old data stripe 1118 is XORed with the new data stripe 1113 stored in the RAID Cache 1108 using the XOR Engine 1105. The result of the XOR operation is temporarily stored in the RAID Cache 1108. The new data stripe is still kept in the RAID Cache. The Flash Controller then issues a flash read command 1116 to the Flash Memory Device N 1125 to read the old parity 1120. The old parity 1120 is then XORed with the result of the previous XOR operation using the XOR Engine 1105. The result of this XOR operation, the new parity, is again stored in the RAID Cache 1108. After generating the new parity, the Flash Controller 1103 issues a flash write command 1115 to the Flash Memory Device 1 1122 to write the new data stripe 1119 from the RAID Cache 1108. The Flash Controller also issues a flash write command 1117 to the Flash Memory Device N 1125 to write the new parity 1121.
FIG. 12 is the write operation implementation in a Flash Electronic Disk taking dual roles in a RAID-5 system according to an embodiment of the present invention. In this implementation, the RAID Control Module 1209 of the Master Disk 1204 is configured as the RAID Controller of the RAID system 1211. The Flash Memory Device 1 1212 of the Master Disk, along with the Slave Disks 1220, 1221, 1222 act as the RAID Slave Disks with the data striped across all the slave disks.
The Flash Controller 1203 of the Master Disk 1204 receives a write command 1218 along with the write data 1219 from the Host 1200. The Flash Controller stores the write data 1219 it received from the Host 1200 in the RAID Cache 1208. Based from the Mapping Table 1202 of the RAID Control Module 1209, the data sent by the Host 1200 should be striped across all the RAID Slave Disks. The RAID Control Module translates the write request received from the Host 1200 into multiple write accesses by converting the write data 1219 into data stripes. The RAID Control Module also generates the corresponding parity stripe by XORing all the data stripes using its XOR Engine 1205. This parity stripe is temporarily stored in the RAID Cache 1208 along with the data stripes. The Flash Controller 1203 then issues a flash write command 1216 to write data stripe 0 1217 to Flash Memory Device 1 1212, an IO write command 1224 to write data stripe 1 1223 to Slave Disk 2 1220 and an IO write command 1226 to write data stripe 2 1225 to Slave Disk 3 1221. The Flash Controller also issues an IO write command 1228 to write the parity stripe 1227 to Slave Disk N 1222.
FIG. 13 is the read operation implementation in a Flash Electronic Disk taking dual roles in a RAID-5 system according to an embodiment of the present invention. In this implementation, the RAID Control Module 1309 of the Master Disk 1304 is configured as the RAID Controller of the RAID system 1311. The Flash Memory Device 1 1312 of the Master Disk, along with the Slave Disks 1324, 1325, 1326 act as the RAID Slave Disks with the data striped across all the slave disks.
The Flash Controller 1303 of the Master Disk 1304 receives a read command 1318 from the Host 1300. The RAID Control Module 1309 being the RAID Controller of the RAID system 1311 interprets the command by referring to its Mapping Table 1302. Based from the Mapping Table, the data being requested by the Host 1300 is found to be striped across all the RAID Slave Disks. The Flash Controller then creates the corresponding Flash Read command for the Flash Memory Device and IO Read commands for the other Slave Disks. A Flash Read command 1316 is sent to Flash Memory Device 1 1312 to get the data stripe 0 1317. An IO Read command 1321 is sent to Slave Disk 2 1324 to get the data stripe 1 1320. An IO Read command 1323 is sent to Slave Disk 3 1325 to get the data stripe 2 1322. The data stripes received from the Flash Memory Device and the Slave Disks are reconstructed in the RAID Cache 1308 and then sent to the requesting Host 1300 as the read data 1319.
FIG. 14 is the read-modify-write operation implementation in a Flash Electronic Disk taking dual roles in a RAID-5 system according to an embodiment of the present invention. In this implementation, the RAID Control Module 1409 of the Master Disk 1404 is configured as the RAID Controller of the RAID system 1411. The Flash Memory Device 1 1418 of the Master Disk, along with the Slave Disks 1422, 1423, 1424 act as the RAID Slave Disks with the data striped across all the slave disks.
Host 1400 sends a write command 1412 to the Master Disk 1404. The RAID Control Module 1409 of the Master Disk receives the write data 1413 and stores it in the RAID Cache 1408. After referring to the Mapping Table 1402, the RAID Control Module discovers that the write request involves a write of only a data stripe. A write of only a data stripe involves a read-modify-write operation. The RAID Control Module first checks from which slave disks will the old data stripe and old parity stripe come from. The RAID Control Module determines that the old data stripe should come from Flash Memory Device 1 and the old parity stripe should come from Slave Disk N.
The Flash Controller 1403 issues a flash read command 1417 to the Flash Memory Device 1 1418 to read the old data stripe 1416. The old data stripe 1416 is XORed with the new data stripe 1413 stored in the RAID Cache 1408 using the XOR Engine 1405. The result of the XOR operation is temporarily stored in the RAID Cache 1408. The new data stripe is still kept in the RAID Cache. The Flash Controller then issues an IO read command 1425 to the Slave Disk N 1424 to read the old parity 1426. The old parity 1426 is then XORed with the result of the previous XOR operation using the XOR Engine 1405. The result of this XOR operation, the new parity, is again stored in the RAID Cache 1408. After generating the new parity, the Flash Controller 1403 issues a flash write command 1414 to the Flash Memory Device 1 1418 to write the new data stripe 1415 from the RAID Cache 1408. The Flash Controller also issues an IO write command 1428 to the Slave Disk N 1424 to write the new parity 1427.
FIG. 15 is a configuration of four Flash Electronic Disks in a RAID System according to an embodiment of the present invention. Each of the four Flash Electronic Disks 1500, 1501, 1502 and 1503 has a RAID Control Module 1504, 1505, 1506 and 1507. All other disk modules are hidden, as the focus is on the role of the RAID Control Modules. The Flash Electronic Disks are interconnected via the one or more generic IO Interface. If the Flash Memory Devices in each Flash Electronic Disk are partitioned in such a way that it allows multiple RAID systems to access it, each Flash Electronic Disk can participate in multiple RAID systems and take on dual roles—RAID Master or Slave Disk. For example, Host 0 1508 configures Flash Electronic Disk 0 1500 to become a RAID Controller with Flash Electronic Disk 1 1501, Flash Electronic Disk 2 1502 and Flash Electronic Disk 3 1503 as its slave disks. For clarity, the RAID system defined by Host 0 1508 is labeled as RAID System 0. Under RAID System 0, the RAID Control Modules 1505, 1506, and 1507 take on the Slave mode. In RAID System 1, Host 1509 configures the RAID Control Module 1505 to take the Master role while RAID Control Modules 1504, 1506 and 1507 take slave roles. The same goes for RAID System 2 which has 1510 as the Host and RAID Control Module 1506 as its Master, and RAID System 3 which has 1511 as the Host and 1507 as the RAID Control Module. FIG. 15 shows a possible configuration of Flash Electronic Disks in one embodiment employing the invention used to its full potential in RAID systems. It shows 4 computer systems using four Flash Electronic Disks in four distinct RAID Systems 0, 1, 2 and 3.
FIG. 16. summarizes the multi-RAID configuration of multiple Flash Electronic Disks according to an embodiment of the present invention. Column 1602 lists the Flash Electronic Disks 0, 1, 2, 3, and N respectively in rows 1620, 1622, 1624, 1626, and 1628. Columns 1604, 1606, 1608, 1610, and 1612 list the Raid System 0, 1, 2, 3, and N, respectively. More Flash Electronic Disks can be added to the configuration of FIG. 15 to produce multiple RAID systems on a plurality of disks. The RAID system becomes more stable and data integrity is high. The configuration also allows non flash electronic disks to be inserted into the RAID system, as long as it conforms to the IO Interface, but its role will be limited only to being a slave, and its address map is limited only to the RAID system where its RAID Controller is attached to.
FIG. 17 illustrates a method to operationally integrate one or more RAID control mechanisms into a flash electronic disk controller, in accordance with one embodiment of the invention. The method starts in operation 1702. Operation 1704 is next and includes incorporating one or more RAID features into a flash electronic disk by adding one or more RAID components in a flash controller, wherein the flash electronic disk is upgraded with the addition of a RAID control module to control the one or more RAID components. Operation 1706 is next and includes receiving a read or write operation command at the flash electronic disk controller from a host. Operation 1708 is next and includes translating the read or write operation command into a command format understood by one or more flash controllers. Operation 1710 is next and includes translating the command format into an instruction format understood by one or more flash memory devices. Operation 1712 is next and includes accessing one or more memory locations in the one or more flash memory devices according to the instruction format to perform a read or write operation for the host. The method ends in operation 1714.
Foregoing described embodiments of the invention are provided as illustrations and descriptions. They are not intended to limit the invention to precise form described. In particular, it is contemplated that functional implementation of invention described herein may be implemented equivalently in hardware, software, firmware, and/or other available functional components or building blocks, and that networks may be wired, wireless, or a combination of wired and wireless.
It is also within the scope of the present invention to implement a program or code that can be stored in a machine-readable or computer-readable medium to permit a computer to perform any of the inventive techniques described above, or a program or code that can be stored in an article of manufacture that includes a computer readable medium on which computer-readable instructions for carrying out embodiments of the inventive techniques are stored. Other variations and modifications of the above-described embodiments and methods are possible in light of the teaching discussed herein.
The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.
These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.

## Claims

1. An apparatus, comprising:
an IO (Input/Output) bus;
a host coupled to the IO bus;
a flash electronic disk coupled via the IO bus to the host, wherein the flash electronic disk incorporates one or more RAID features, said flash electronic disk comprising a flash controller having one or more RAID components, wherein the flash electronic disk includes a RAID control module to control the one or more RAID components, wherein the flash controller receives a read operation command or write operation command from the host and translates the read operation command or write operation command into a command format that can be understood by one or more flash memory devices;
wherein the flash electronic disk further comprises one or more flash memory devices and a flash interconnect coupled to the flash controller and to the one or more flash memory devices;
wherein the flash controller is configured to translate the command format into an instruction format that can be understood by the one or more flash memory devices;
wherein the one or more flash memory devices include one or more memory locations that can be accessed according to the instruction format to perform a read operation or write operation for the host;
wherein the flash interconnect is configured to handle data transmission between the host and the one or more flash memory devices;
wherein the flash memory devices comprise at least a first flash memory device, a second flash memory device, and a third flash memory device;
wherein the RAID control module in the flash controller is configured to distribute data from the host across the flash memory devices by data striping;
wherein the RAID control module distributes a first data stripe of the data into the first flash memory device, distributes a second data stripe of the data into the second flash memory device, and distributes a parity of the data into the third flash memory device;
wherein the flash controller is coupled to the IC bus;
a plurality of disks coupled to the IC bus, wherein the plurality of disks comprises a first disk, a second disk, and a third disk;
wherein the flash controller transfers the first data stripe in the first flash memory device to the first disk;
wherein the flash controller transfers the second data stripe in the second flash memory device to the second disk; and
wherein the flash controller transfers the parity of the data in the third flash memory device to the third disk.

2. The apparatus of claim 1, wherein:
the RAID control module comprises a RAID cache that serves as a temporary data storage during one or more parity calculations.

3. The apparatus of claim 1, wherein:
the RAID control module comprises a mapping table for address translation of the read operation and write operation commands received from the host.

4. The apparatus of claim 1, wherein:
the RAID control module comprises an XOR engine that is used during one or more parity calculations.

5. The apparatus of claim 1, wherein:
the RAID control module comprises an XOR engine that is used during one or more parity calculations, a RAID cache that serves as a temporary data storage during one or more parity calculations and a mapping table for address translation of the read operation and write operation commands received from the host.

6. The apparatus of claim 1, wherein the one or more flash memory devices are used as a slave disk instead of a cache memory.

7. The apparatus of claim 1, wherein the one or more flash memory devices are used as a slave disk instead of a cache memory by remapping a plurality of memory locations of the one or more flash memory devices on a new addressing scheme kept by the RAID control module in a mapping table.

8. The apparatus of claim 1, wherein the one or more flash memory devices are distributed to a number of RAID systems, wherein the flash electronic disk has one or more flash memory devices assigned to the RAID control module, and a remainder of the flash memory devices are assigned to another RAID control module in another RAID system.

9. The apparatus of claim 1, wherein the one or more flash memory devices are used as hot spare replacement disks.

10. The apparatus of claim 1, wherein the one or more flash memory devices are used as hot spare replacement disks, wherein one or more replacement disks allow the RAID control module to perform reconstruction to regenerate data from a failed disk by reading the data from one or more surviving slave disks.

11. A method comprising:
incorporating one or more RAID features into a flash electronic disk by adding one or more RAID components in a flash controller, wherein the flash electronic disk includes a RAID control module to control the one or more RAID components;
receiving a read operation command or write operation command at the flash electronic disk from a host;
translating the read operation command or write operation command into a command format understood by one or more flash memory devices;
translating the command format into an instruction format understood by one or more flash memory devices;
handling, by a flash interconnect coupled to the flash controller and to the one or more flash memory devices, data transmission between the host and the one or more flash memory devices;
accessing one or more memory locations in the one or more flash memory devices according to the instruction format to perform a read operation or write operation for the host;
distributing, by the RAID control module in the flash controller, data from the host across the one or more flash memory devices by data striping;
wherein the one or more flash memory devices comprise at least a first flash memory device, a second flash memory device, and a third flash memory device;
wherein the RAID control module distributes a first data stripe of the data into the first flash memory device, distributes a second data stripe of the data into the second flash memory device, and distributes a parity of the data into the third flash memory device;
wherein the host and the flash controller are both coupled to an IC (input/output) bus;
wherein a plurality of disks is coupled to the IC bus, wherein the plurality of disks comprises a first disk, a second disk, and a third disk;
transferring, by the flash controller, the first data stripe in the first flash memory device to the first disk;
transferring, by the flash controller, the second data stripe in the second flash memory device to the second disk; and
transferring, by the flash controller, the parity of the data in the third flash memory device to the third disk.

12. The method of claim 11, wherein incorporating the one or more RAID features into the flash electronic disk includes adding the RAID control module having a RAID cache that serves as a temporary data storage during one or more parity calculations.

13. The method of claim 11, wherein incorporating the one or more RAID features into the flash electronic disk includes adding a mapping table for address translation of one or more read operation commands or write operation commands received from the host.

14. The method of claim 11, wherein incorporating the one or more RAID features into the flash electronic disk includes adding the RAID control module having an XOR engine that is used during one or more parity calculations.

15. The method of claim 11, wherein incorporating the one or more RAID features into the flash electronic disk includes adding the RAID control module having an XOR engine that is used during one or more parity calculations, adding a RAID cache that serves as a temporary data storage during the one or more parity calculations and adding a mapping table for address translation of the read operation or write operation commands received from the host.

16. The method of claim 11, wherein the one or more flash memory devices are used as a slave disk instead of a cache memory.

17. The method of claim 11, wherein the one or more flash memory devices are used as a slave disk instead of a cache memory and a plurality of memory locations of the flash memory devices are remapped on a new addressing scheme kept by the RAID control module in a mapping table.

18. The method of claim 11, wherein the one or more flash memory devices are used as a slave disk instead of a cache memory and a plurality of memory locations of the flash memory devices are remapped on a new addressing scheme kept by the RAID control module in a mapping table, and the one or more flash memory devices are distributed among one or more other RAID systems by assignment to one or more RAID controllers for the one or more other RAID systems.

19. The method of claim 11, wherein the one or more flash memory devices are used as hot spare replacement disks, wherein one or more replacement disks allow the RAID control module to perform reconstruction to regenerate data from a failed disk by reading the data from one or more surviving slave disks.

20. A method comprising:
incorporating one or more RAID features into a flash electronic disk by adding one or more RAID components in a flash controller, wherein the flash electronic disk includes a RAID control module to control the one or more RAID components, including adding the RAID control module having an XOR engine that is used during one or more parity calculations, adding a RAID cache that serves as a temporary data storage during the one or more parity calculations and adding a mapping table for address translation of one or more commands received from a host;
receiving a read operation command or write operation command at the flash electronic disk from the host;
translating the read operation command or write operation command into a command format understood by one or more flash memory devices;
translating the command format into an instruction format understood by one or more flash memory devices;
handling, by a flash interconnect coupled to the flash controller and to the one or more flash memory devices, data transmission between the host and the one or more flash memory devices;
accessing one or more memory locations in the one or more flash memory devices according to the instruction format to perform a read operation or write operation for the host;
distributing, by the RAID control module in the flash controller, data from the host across the one or more flash memory devices by data striping;
wherein the one or more flash memory devices comprise at least a first flash memory device, a second flash memory device, and a third flash memory device;
wherein the RAID control module distributes a first data stripe of the data into the first flash memory device, distributes a second data stripe of the data into the second flash memory device, and distributes a parity of the data into the third flash memory device;
wherein the host and the flash controller are both coupled to an IC (input/output) bus;
wherein a plurality of disks is coupled to the IC bus, wherein the plurality of disks comprises a first disk, a second disk, and a third disk;
transferring, by the flash controller, the first data stripe in the first flash memory device to the first disk;
transferring, by the flash controller, the second data stripe in the second flash memory device to the second disk; and
transferring, by the flash controller, the parity of the data in the third flash memory device to the third disk.

21. An apparatus comprising:
a flash electronic disk comprising:
a flash controller, wherein the flash controller includes a RAID controller;
a plurality of flash memory devices; and
a flash interconnect coupled to the flash controller and to the plurality of flash memory devices;

wherein the flash electronic disk receives write and read commands from a host;
wherein the flash controller is configured to translate the write and read commands into flash native commands which are understood by the plurality of flash memory devices;
wherein the flash interconnect is configured to handle data transmission between the host and the plurality of flash memory devices;
wherein the plurality of flash memory devices comprises at least a first flash memory device, a second flash memory device, and a third flash memory device;
wherein the RAID controller in the flash controller is configured to distribute data from the host across the plurality of flash memory devices by data striping;
wherein the RAID controller distributes a first data stripe of the data into the first flash memory device, distributes a second data stripe of the data into the second flash memory device, and distributes a parity of the data into the third flash memory device;
wherein the flash controller and the host are both coupled to an IC (input/output) bus;
wherein a plurality of disks is coupled to the IO bus, wherein the plurality of disks comprises a first disk, a second disk, and a third disk;
wherein the flash controller transfers the first data stripe in the first flash memory device to the first disk;
wherein the flash controller transfers the second data stripe in the second flash memory device to the second disk; and
wherein the flash controller transfers the parity of the data in the third flash memory device to the third disk.

22. The apparatus of claim 21, wherein the RAID controller comprises an XOR engine that is used during one or more parity calculations, a RAID cache that serves as a temporary data storage during one or more parity calculations, and a mapping table for address translation of the write and read commands received from the host.

23. A method comprising:
receiving, by a flash electronic disk, write and read commands from a host;
translating, by a flash controller in the flash electronic disk, the write and read commands into flash native commands which are understood by a plurality of flash memory devices in the flash electronic disk;
handling, by a flash interconnect coupled to the flash controller and to the plurality of flash memory devices, data transmission between the host and the plurality of flash memory devices;
distributing, by a RAID controller in the flash controller, data from the host across the plurality of flash memory devices by data striping;
wherein the plurality of flash memory devices comprises at least a first flash memory device, a second flash memory device, and a third flash memory device;
wherein the RAID controller distributes a first data stripe of the data into the first flash memory device, distributes a second data stripe of the data into the second flash memory device, and distributes a parity of the data into the third flash memory device;
wherein the host and the flash controller are both coupled to an IO (input/output) bus;
wherein a plurality of disks is coupled to the IO bus, wherein the plurality of disks comprises a first disk, a second disk, and a third disk;
transferring, by the flash controller, the first data stripe in the first flash memory device to the first disk;
transferring, by the flash controller, the second data stripe in the second flash memory device to the second disk; and
transferring, by the flash controller, the parity of the data in the third flash memory device to the third disk.

24. The method of claim 23, wherein the RAID controller comprises an XOR engine that is used during one or more parity calculations, a RAID cache that serves as a temporary data storage during one or more parity calculations, and a mapping table for address translation of the write and read commands received from the host.

25. An article of manufacture, comprising:
a non-transitory computer-readable medium having stored thereon instructions operable to permit an apparatus to:
receive, by a flash electronic disk, write and read commands from a host;
translate, by a flash controller in the flash electronic disk, the write and read commands into flash native commands which are understood by a plurality of flash memory devices in the flash electronic disk;
handle, by a flash interconnect coupled to the flash controller and to the plurality of flash memory devices, data transmission between the host and the plurality of flash memory devices;
distribute, by a RAID controller in the flash controller, data from the host across the plurality of flash memory devices by data striping;
wherein the plurality of flash memory devices comprises at least a first flash memory device, a second flash memory device, and a third flash memory device;
wherein the RAID controller distributes a first data stripe of the data into the first flash memory device, distributes a second data stripe of the data into the second flash memory device, and distributes a parity of the data into the third flash memory device;
wherein the host and the flash controller are both coupled to an IO (input/output) bus;
wherein a plurality of disks is coupled to the IO bus, wherein the plurality of disks comprises a first disk, a second disk, and a third disk;
transfer, by the flash controller, the first data stripe in the first flash memory device to the first disk;
transfer, by the flash controller, the second data stripe in the second flash memory device to the second disk; and
transfer, by the flash controller, the parity of the data in the third flash memory device to the third disk.

26. The article of manufacture of claim 25, wherein the RAID controller comprises an XOR engine that is used during one or more parity calculations, a RAID cache that serves as a temporary data storage during one or more parity calculations, and a mapping table for address translation of the write and read commands received from the host.