Method and system for a high-priority read based on an in-place suspend/resume write

One embodiment facilitates a high-priority read. During operation, the system receives, by a controller module of a storage device, a first request to write first data to a non-volatile memory of the storage device. The system commences a write operation to write the first data to the non-volatile memory. In response to detecting a second request to read second data from the non-volatile memory, the system: suspends the write operation; reads the second data from the non-volatile memory; and resumes the suspended write operation.

BACKGROUND

Field

This disclosure is generally related to the field of data storage. More specifically, this disclosure is related to a method and system for a high-priority read based on an in-place suspend/resume write.

Related Art

The proliferation of the Internet and e-commerce continues to create a vast amount of digital content. Various storage systems have been created to access and store such digital content. In a standard storage system, a server may store data in a non-volatile memory, such as NAND flash component. A NAND flash typically includes multiple dies, where a single die can include a hierarchy of multiple plane, blocks, and pages. Data is written to and read from a page-level unit. A typical write operation to a NAND page can occupy an entire page buffer of the involved NAND die. As a result, a read request (e.g., a read operation) received during an ongoing write operation cannot begin or complete until the ongoing write operation is completed. That is, if a read operation is requested for the same die on which a write operation is currently being performed, the read operation must wait until the write operation is completed. Thus, the latency involved in performing the read operation on the die is dependent on completion of an ongoing write operation on the same NAND die.

Writing data to a page may require approximately several milliseconds, while reading data from a page may require only hundreds of microseconds. Thus, a read operation results in a higher latency from a delayed start in waiting for completion of an ongoing write operation, where the delay may be on the order of milliseconds. Given both the increasing density of current NAND dies and the decreasing size of computer components in general, a read operation may result in a hit on the same NAND die on which an ongoing write operation is being performed, thus resulting in a higher latency. This higher latency can decrease the efficiency of a storage system.

SUMMARY

One embodiment facilitates a high-priority read. During operation, the system receives, by a controller module of a storage device, a first request to write first data to a non-volatile memory of the storage device. The system commences a write operation to write the first data to the non-volatile memory. In response to detecting a second request to read second data from the non-volatile memory, the system: suspends the write operation; reads the second data from the non-volatile memory; and resumes the suspended write operation.

In some embodiments, the system maps a logical block address of the first data to a first physical block address of the non-volatile memory, wherein the first physical block address is associated with a first page of the non-volatile memory.

In some embodiments, in response to detecting a first timeout based on a timestamp for the first data, the system maps the logical block address of the first data to a second physical block address of the non-volatile memory, wherein the second physical block address is associated with a second page of the non-volatile memory. The system marks the first page as available to be recycled. The system updates the timestamp for the first data, and writes the first data to the second page, wherein a second timeout is detected based on the updated timestamp for the first data.

In some embodiments, the system processes the first data by: encoding the first data based on a cyclic redundancy check; compressing the encoded data; encrypting the compressed data; encoding the encrypted data based on an error correction code (ECC); adjusting a format of the ECC-encoded data; and inserting a timestamp for the adjusted data.

In some embodiments, suspending the write operation is in response to detecting a completion of an ongoing verify procedure in an incremental step pulse program.

In some embodiments, subsequent to suspending the write operation, the system receives, by the controller, sensed data which includes data of the first data still to be written to the non-volatile memory, and stores the sensed data in a data buffer of the controller. Subsequent to resuming the suspended write operation, the system transmits, by the controller, the sensed data to the non-volatile memory.

In some embodiments, the non-volatile memory is a NAND flash memory which includes a plurality of dies, wherein a die includes a plurality of planes, wherein a plane includes a plurality of blocks, and wherein a block includes a plurality of pages. The non-volatile memory may only be accessed by a single read or write operation at a time.

Another embodiment facilitates a high-priority read. During operation, the system receives, by a controller module of a storage device, a request to read data stored in a non-volatile memory of the storage device. In response to determining that the non-volatile memory is performing an ongoing write operation, the system: suspends the ongoing write operation; reads the requested data from the non-volatile memory; and resumes the suspended write operation.

In some embodiments, subsequent to suspending the ongoing write operation, the system receives, by the controller, sensed data which includes data still to be written to the non-volatile memory, and stores the sensed data in a data buffer of the controller. Subsequent to resuming the suspended write operation, the system transmits, by the controller, the sensed data to the non-volatile memory.

In some embodiments, the system obtains a physical block address of the non-volatile memory, wherein the physical block address maps to a logical block address of the requested data, wherein reading the requested data from the non-volatile memory is based on the physical block address.

In some embodiments, suspending the ongoing write operation is in response to detecting a completion of an ongoing verify procedure in an incremental step pulse program.

In some embodiments, the system verifies the requested data read from the non-volatile memory, and transmits the verified data to a requesting host.

In some embodiments, the non-volatile memory may only be accessed by a single read or write operation at a time.

Another embodiment provides a system which facilitates a high-priority read. During operation, the system detects a new request to read first data from a non-volatile memory. The system suspends a write operation to write second data to the non-volatile memory. The system reads the first data from the non-volatile memory. The system resumes the suspended write operation.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled in the art to make and use the embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Thus, the embodiments described herein are not limited to the embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein.

Overview

The embodiments described herein solve the problem of facilitating a high-priority read operation on a NAND flash (e.g., a die) with an ongoing write operation by suspending the ongoing write operation, performing the read operation, and resuming the suspended write operation. Data is typically written to and read from a page on a single die, which has a single page buffer. During a write operation, the page buffer of the single die may be full, which prevents any other I/O operations from occurring on that die. That is, if a read operation is requested for the same die on which a write operation is currently being performed, the read operation must wait until the ongoing write operation is completed. Thus, the latency involved in performing the read operation on the die is dependent on completion of an ongoing write operation on the same die.

Writing data to a page may require approximately several milliseconds, while reading data from a page may require only hundreds of microseconds. Thus, a read operation results in a higher latency from a delayed start in waiting for completion of an ongoing write operation, where the delay may be on the order of milliseconds. Given both the increasing density of current NAND dies and the decreasing size of computer components in general, a read operation may result in a hit on the same NAND die on which an ongoing write operation is being performed, thus resulting in a higher latency. This higher latency can decrease the efficiency of a storage system.

The embodiments described herein address this inefficiency by providing a storage system which facilitates a high-priority read operation on a NAND flash (e.g., a die) with an ongoing write operation by suspending the ongoing write operation, performing the read operation, and resuming the suspended write operation. A storage system (e.g., a solid state drive or SSD) can include a controller and multiple non-volatile memory components (e.g., NAND flash components or NAND dies). When the system receives a high-priority read request, and the requested data resides on a die which is performing an ongoing write operation, the system can suspend the ongoing write operation, read the requested data, and resume the suspended write operation. Data to be written to and read from a die is stored in a page buffer of the die, while data from a suspended write operation is stored in a data buffer of the controller, as described below in relation toFIG. 3. The execution of an I/O operation (e.g., a high-priority read or an ongoing, suspended, or resume write operation) may be based on an incremental step pulse program, as described below in relation toFIG. 4.

Thus, the embodiments described herein provide a system which improves the efficiency of a storage system, where the improvements are fundamentally technological. The improved efficiency can include an improved performance in latency for completion of I/O tasks, as well as an improved Quality of Service (QoS) for performing read operations. The system provides a technological solution (i.e., a storage system which facilitates a high-priority read by suspending an ongoing write operation, performing the read, and resuming the suspended write operation, and further includes a controller which facilitates the high-priority read) to the technological problem of reducing latency in I/O tasks, improving the QoS, and improving the overall efficiency of the system.

The terms “storage server,” “storage device,” and “storage system” refer to a server, device, or system which can include multiple drives and multiple memory modules or components.

The term “drive” refers to a hard drive in a storage system, such as a solid state drive (SDD) or a hard disk drive (HDD).

The term “non-volatile memory” refers to long-term persistent computer storage, such as a NAND flash memory of an SSD. A NAND flash can include multiple dies, each die can include multiple planes, each plane can include multiple blocks, and each block can include multiple pages. A “die” can include a page buffer for temporary storage of data to be read from or written to the die. Data stored in the page buffer may timeout based on a timestamp for the stored data.

The terms “controller module” and “controller” refer to a module located in a storage server, and may be used interchangeably. In the embodiments described herein, the controller is situated in the drive between the non-volatile memory and a requesting host. The controller can include a data buffer, into which data is written for temporary storage, e.g., data associated with a suspended write operation. The controller's data buffer can also include data which is being processed by the controller, including encoded/decoded, compressed/decompressed, encrypted/decrypted, ECC-encoded/-decoded, formatted/re-formatted, and timestamped.

The term “ECC-encoding” refers to encoding data based on an error correction code, while the term “ECC-decoding” refers to decoding data based on the error correction code. An “ECC-encoder/decoder” is a module which performs ECC-encoding/decoding.

Exemplary Environment and General Exemplary Communication

FIG. 1Aillustrates an exemplary environment100that facilitates a high-priority read, in accordance with an embodiment of the present application. Environment100can include a computing device102which is associated with a user104. Computing device102can include, for example, a tablet, a mobile phone, an electronic reader, a laptop computer, a desktop computer, or any other computing device. Computing device102can communicate via a network110with servers112,114, and116, which can be part of a distributed storage system. Servers112-116can include a storage server, which can a CPU, an interface card, and storage devices or modules. For example, server116can include a CPU122, a network interface card (NIC)124, and solid state drives (SSDs)132,136, and140, where each SDD can have, respectively, its own controller134,138, and142. Each SSD can include non-volatile memory, including multiple non-volatile memory modules or components. For example, SSD140can include NAND flash memory, including multiple NAND dies150.1-150.r. A NAND die (e.g., NAND die150.1) can include multiple planes152.1-152.s. A plane (e.g., plane152.s) can include multiple blocks154.1-154.t. A block (e.g., block154.t) can include multiple pages156.1-156.u.

Data can be read from or written to a NAND die based on a page-level access. During operation, server116can receive a high-priority read request. If the requested data resides on a die which is performing an ongoing write operation (e.g., on NAND die150.1, and specifically from page156.1), the system can suspend the ongoing write operation, read the requested data (from page156.1), and resume the suspended write operation.

Thus, server116depicts a high-level architecture for a system which facilitates a high-priority read operation on a non-volatile memory component which is currently performing a write operation. Data to be written to and read from a die is stored in a page buffer of the die, while data from a suspended write operation is stored in a data buffer of the controller, as described below in relation toFIG. 3.

FIG. 1Bpresents a flowchart160illustrating a method which facilitates a high-priority read, in accordance with an embodiment of the present application. During operation, the system detects a new request to read first data from a non-volatile memory (operation162). The system suspends a write operation to write second data to the non-volatile memory (operation164). The system reads the first data from the non-volatile memory (operation166). Subsequently, the system resumes the suspended write operation (operation168).

A general data flow is described below in relation toFIGS. 2B and 3. An exemplary data flow in a read operation is described below in relation toFIG. 5, and an exemplary data flow in a write operation is described below in relation toFIGS. 6 and 7A-7C.

Exemplary Environment in the Prior Art Vs. Exemplary Embodiment

FIG. 2Aillustrates an exemplary environment200for handling a read operation during an ongoing write operation, in accordance with the prior art. Environment200can include multiple pages which are performing ongoing write operations, which are represented over a time202. For example: page210.1can be executing write operations212.1and214.1; page210.2can be executing write operations212.2and214.2; page210.9can be executing write operations212.9and214.9; and page210.10can be executing write operations212.10and214.10. Note that while environment200depicts only 10 pages of a non-volatile memory module, a non-volatile memory module may include many more pages.

Assume that the write operations212.1-212.10and214.1-214.10are performed in a sequential manner. At a time204, the NAND memory may receive a read request220, for data which is to be read from page210.9. However, page210.9is currently in the middle of write operation214.9. In a traditional read operation to access a NAND die with an ongoing write operation, the read operation must wait for the ongoing write operation to complete before it is performed. Thus, read operation222can only be performed after execution of write operation214.9, such that a complete read request224may only occur at a time206. This is because the page buffer for a single NAND die can only hold a certain amount of information at a page-level unit. As a result, a high latency may occur between time204and time206. The latency can decrease the efficiency of a storage system.

FIG. 2Billustrates an exemplary environment230for handling a read operation during an ongoing write operation, in accordance with an embodiment of the present application. Environment230includes the same pages and write operations as environment200. However, in environment230, at a time234, the NAND memory may receive a read request240, for data which is to be read from page210.9. Although page210.9is currently in the middle of write operation214.9, the system can suspend write operation214.9(whereby a portion214.9ahas been written to page210.9) and perform a read operation242. At a time236, upon a complete read request244, the system can resume the suspended write operation214.9(whereby the remaining portion214.9bcan be written to page210.9). The latency which occurs between time233and time236can be significantly lower than the latency which occurs between time204and time206in the prior art as depicted in environment200.

Thus, embodiments of the present invention provide a system which decreases the latency in performing a read operation. The read operation may be associated with a high-priority read, which can be based on a set of predetermined conditions configured by the user or the system. Furthermore, by decreasing the latency of these read operations, the system can provide an improved QoS and also mitigate the write amplification involved in writing data to non-volatile memory at a page-level access.

Exemplary Communication for Facilitating a High-Priority Read

FIG. 3illustrates exemplary communication in an SSD300between an SSD controller302and a NAND die310.2for facilitating a high-priority read, in accordance with an embodiment of the present application. SSD300can include SSD controller302, which includes a data buffer304. SSD300can also include multiple NAND dies310.1-310.r, which can each include, respectively, page buffers312.1-312.r. When a high-priority read operation is received for a specific die, and an ongoing write operation in the specific die is suspended, the data that is being written to the specific die is moved from the non-volatile memory to the controller. For example, the data being written is moved from a page buffer312.2of NAND die310.2to a data buffer304of SSD controller302in a communication320. Data buffer304can be supported by a power loss protection. Thus, data that is stored in data buffer304will not be lost during a loss in power or a power failure because SSD300itself can provide sufficient charge or power for writing the data into NAND die310.2(or another NAND die if NAND die310.2becomes unavailable, as described below in relation toFIGS. 7A and 8). When the high-priority read operation is complete, the suspended write operation is resumed at the same physical page. The remaining data to be written is moved from data buffer304back to page buffer312.2in a communication322. Instead of resuming from an erase program state, the write operation resumes from the state of the program upon initially suspending the write operation. A detailed description of resuming the write operation is described below in relation toFIG. 4.

FIG. 4illustrates an exemplary threshold voltage distribution400in an incremental step pulse program (ISPP) for facilitating a high-priority read, in accordance with an embodiment of the present application. Distribution400includes a voltage threshold (Vth)401, and various procedures in an incremental step pulse program (ISPP). An ISPP can be used to maintain a tight cell threshold voltage distribution for high reliability. In general, ISPP uses a “program and verify” strategy, which involves repeating program and verify cycles on the cells of a flash memory. For example, distribution400illustrates the threshold voltage moving from the erase state (indicated by a program402with a wider distribution) to a verify404, and a sense406, which occurs when the program is suspended in order to perform to a high-priority read (indicated by a program ceased420). When the program is resumed after the read is completed, the system performs a sense408, and then proceeds as before with a program410and a verify412, etc.

In the embodiments described herein, ISPP is used in a modified manner by including a sense operation both upon: a) suspending an ongoing write operation and starting a high-priority read operation (sense406); and b) completing the high-priority read operation and resuming the suspended write operation (sense408). While some ISPP-based programs include cycles of program, verify, and sense, the embodiments described herein insert an additional sense (i.e., sense408), to determine the current threshold voltage of the cell. This additional sense procedure may alleviate issues from potential cross-talking or affected previous sense procedures based on the coupling effect of neighboring cells. Thus, by inserting additional sense408upon completion of the high-priority read, the system can provide an improved functioning for operation of the flash memory.

Exemplary Communication During a Read Operation

FIG. 5presents a flowchart500illustrating a method500for reading data in a system which facilitates a high-priority read, in accordance with an embodiment of the present application. During operation, the system receives, by a controller module of a storage device, a request to read data stored in a non-volatile memory of the storage device (operation502). The system obtains, by a flash translation layer (FTL) module, a physical block address (PBA) of the non-volatile memory, wherein the physical block address maps to a logical block address for the requested data (operation504). If the non-volatile memory is not performing an ongoing write operation (decision506), the system reads the requested data from the non-volatile memory based on the physical block address (operation508). The system verifies the requested data read from the non-volatile memory (operation510), and transmits the verified data to a requesting host (operation512).

If the non-volatile memory is performing an ongoing write operation (decision506), the system suspends the ongoing write operation upon detecting completion of an ongoing verify procedure in an incremental step pulse program (ISPP) (operation522). The system receives, by the controller, sensed data which includes data still be written to the non-volatile memory (operation524). The system reads the requested data from the non-volatile memory based on the physical block address (operation526), and the operation continues as described above at operation510and also at operation528. The system resumes the suspended write operation (operation528). The system transmits, by the controller, the sensed data back to the non-volatile memory (operation530).

Exemplary Communication During a Write Operation

FIG. 6presents a flowchart600illustrating a method for writing data in a system which facilitates a high-priority read, in accordance with an embodiment of the present application. During operation, the system receives, by a controller module of a storage device, a first request to write first data to a non-volatile memory of the storage device (operation602). The system commences a write operation to write the first data to the non-volatile memory (operation604). The system detects a second request to read second data from the non-volatile memory (operation606). The system suspends the write operation (operation608), reads the second data from the non-volatile memory (operation610), and resumes the suspended write operation (operation612).

FIG. 7Apresents a flowchart700illustrating a method for writing data in a system which facilitates a high-priority read, in accordance with an embodiment of the present application. During operation, the system receives, by a controller module of a storage device, a first request to write first data to a non-volatile memory of the storage device (operation702). The system maps a logical block address (LBA) of the first data to a first physical block address (PBA) of the non-volatile memory, wherein the first PBA is associated with a first page of the non-volatile memory (operation704). The system processes the first data (e.g., by encoding, compressing, encrypting, error correction code encoding, format-adjusting, and timestamping the first data) (operation706). The system transmits, by the controller, the first data to a page buffer of the non-volatile memory (operation708). If the system does not detect a first timeout based on the timestamp for the first data (decision710), the operation continues as described at Label A ofFIG. 7B.

If the system does detect a first timeout based on the timestamp for the first data (decision710), the system maps the logical block address of the first data to a second physical block address of the non-volatile memory, wherein the second physical block address is associated with a second page of the non-volatile memory (operation712). Note that decision710can also include detecting a condition that makes the first page unavailable, such as a timeout of the data being written, a failure of the page being written to, or any other reason which results in the page or die being unavailable. This allows the system to avoid using an unavailable non-volatile memory or NAND die. The system marks the first page as available to be recycled (operation714) (e.g., available for a garbage collection process), and inserts an updated timestamp for the first data (operation716). The system writes the first data to the second page, wherein a second timeout is detected based on the updated timestamp for the first data (operation718). The operation continues as described at operation706.

FIG. 7Bpresents a flowchart730illustrating a method for writing data in a system which facilitates a high-priority read, in accordance with an embodiment of the present application. During operation, the system commences a write operation by programming the first page of the non-volatile memory in a multi-round incremental step pulse program (ISPP) (operation732). If the system does not detect a second request to read a second data from the non-volatile memory (decision734), the operation continues as depicted at operation756ofFIG. 7C.

If the system does detect a second request to read a second data from the non-volatile memory (decision734), the system suspends the write operation (operation736). The second request can be detected as a high-priority read, or as a “read-pause” (i.e., a read operation which causes a pause of an ongoing write). The system detects a completion of an ongoing verify procedure in the ISPP (operation738). The system receives, by the controller, sensed data which includes data of the first data still to be written to the non-volatile memory (operation740). The system reads, by the controller, the second data from the non-volatile memory (operation742). If the read operation is not complete (decision744), the operation continues at operation742. If the read operation is complete, the operation continues at Label B ofFIG. 7C.

FIG. 7Cpresents a flowchart750illustrating a method for writing data in a system which facilitates a high-priority read, in accordance with an embodiment of the present application. During operation, the system resumes the suspended write operation (operation752). The system transmits, by the controller to the page buffer of the non-volatile memory, the sensed data (operation754). If the program (i.e., the write operation) is not complete, the system continues at operation732ofFIG. 7B. If the program is complete, the system marks, by the controller, the write operation as successfully storing the data in persistent storage (i.e., the non-volatile memory) (operation758).

Remapping a Write Operation Given a Timeout or an Unavailable Die

FIG. 8presents exemplary communication in an SSD800for remapping a write operation, which facilitates a high-priority read, in accordance with an embodiment of the present application. SSD800can include an SSD controller800, which can include or interact with an LBA to PBA mapping table840. SSD800can also include multiple NAND dies802-816, with which SSD controller can communicate. NAND die804can commence performing a write operation822(communication832). SSD controller may determine to insert a high-priority read operation during the ongoing write operation, in which case the data to be written is moved from a page buffer of NAND die804to a data buffer of controller800(communication834), as depicted above in relation toFIG. 3. SSD controller can then send the read request to NAND die804, which performs the requested read operation820, and sends back the requested data (communications830). SSD controller300can detect a condition which triggers a remapping of the write operation. That is, the system can map the logical block address of the data to be written to an updated physical block address. The triggering condition can include: detecting a timeout of the data to be written, based on a timestamp for the data; an unavailability of the affected page of the non-volatile memory (e.g., a page of NAND die804); a failure of the affected page to which the data is being written (e.g., a page of NAND die804); and any other reason which results in the page or die being unavailable.

After remapping the LBA to the updated PBA, the system marks the affected page as available to be recycled (e.g., available for a garbage collection process), updates the timestamp for the data, and writes the data to a new page associated with the updated physical block address (communication836).

Exemplary Computer System and Apparatus

FIG. 9illustrates an exemplary computer system900that facilitates a high-priority read, in accordance with an embodiment of the present application. Computer system900includes a processor902, a controller904, a non-volatile memory906, and a storage device908. Computer system900may be a client-serving machine. Computer system900can also include volatile memory (not shown), which can include, e.g., RAM, that serves as a managed memory, and can be used to store one or more memory pools. Non-volatile memory906can include persistent storage that is accessed via controller904. Furthermore, computer system900can be coupled to a display device910, a keyboard912, and a pointing device914. Storage device908can store an operating system916, a content-processing system918, and data934.

Content-processing system918can include instructions, which when executed by computer system900, can cause computer system900to perform methods and/or processes described in this disclosure. Specifically, content-processing system918can include instructions for receiving and transmitting data packets, including a request to write or read data, and data to be processed (e.g., encoded, encrypted, compressed, adjusted, timestamped) and stored. Content-processing system918can further include instructions for receiving, by a controller module of a storage device, a first request to write first data to a non-volatile memory of the storage device (communication module920). Content-processing system918can include instructions for commencing a write operation to write the first data to the non-volatile memory (data-writing module922). Content-processing system918can include instructions for, in response to detecting a second request to read second data from the non-volatile memory (communication module920): suspending the write operation (operation-controlling module932); reading the second data from the non-volatile memory (data-reading module924); and resuming the suspended write operation (operation-controlling module932).

Content-processing system918can include instructions for mapping a logical block address of the first data to a first physical block address of the non-volatile memory (PBA-managing module928). Content-processing system918can include instructions for, in response to detecting a first timeout based on a timestamp for the first data (condition-detecting module930): mapping the logical block address of the first data to a second physical block address of the non-volatile memory (PB A-managing module928); marking the first page as available to be recycled (data-processing module926); updating the timestamp for the first data (data-processing module926); and writing the first data to the second page (data-writing module922).

Content-processing system918can include instructions for receiving, by a controller module of a storage device, a request to read data stored in a non-volatile memory of the storage device (communication module920). Content-processing system918can include instructions for, in response to determining that the non-volatile memory is performing an ongoing write operation (condition-detecting module930): suspending the ongoing write operation (operation-controlling module932); reading the requested data from the non-volatile memory (data-reading module924); and resuming the suspended write operation (operation-controlling module932).

Data934can include any data that is required as input or that is generated as output by the methods and/or processes described in this disclosure. Specifically, data934can store at least: a request to read or write data; data to be written, read, stored, or accessed; processed or stored data; encoded or decoded data; encrypted or compressed data; decrypted or decompressed data; an error correction code (ECC) encoding or decoding; an indicator of a suspended write operation; a logical block address; a physical block address; a data buffer; a page buffer; a timestamp; a timeout; a condition; sensed data; an incremental step pulse program (ISPP); any procedure in an ISPP; and an indicator of data being ready to be recycled.

FIG. 10illustrates an exemplary apparatus1000that facilitates a high-priority read, in accordance with an embodiment of the present application. Apparatus1000can comprise a plurality of units or apparatuses which may communicate with one another via a wired, wireless, quantum light, or electrical communication channel. Apparatus1000may be realized using one or more integrated circuits, and may include fewer or more units or apparatuses than those shown inFIG. 10. Further, apparatus1000may be integrated in a computer system, or realized as a separate device which is capable of communicating with other computer systems and/or devices. Specifically, apparatus1000can comprise units1002-1014which perform functions or operations similar to modules920-932of computer system900ofFIG. 9, including: a communication unit1002; a data-writing unit1004; a data-reading unit1006; a data-processing unit1008; a PBA-managing unit1010; a condition-detecting unit1012; and an operation-controlling unit1014.

The foregoing embodiments described herein have been presented for purposes of illustration and description only. They are not intended to be exhaustive or to limit the embodiments described herein to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the embodiments described herein. The scope of the embodiments described herein is defined by the appended claims.