Abstract:
A storage solution includes a first enclosure having modules and non-volatile memory, such as hard disk drives. These modules convert file I/O to block I/O. A second enclosure includes second modules and non-volatile memory. These modules are operable to cause the block I/O to be stored on the non-volatile storage in either the first or second enclosure. Thus, the modules that perform block I/O storage can access storage that resides in the file I/O server. In a different arrangement, the storage system has an enclosure having modules and non-volatile memory. One module converts file I/O to block I/O. Another module transfers block I/O to the non-volatile memory. The first and second modules are interconnected via a data bus. Block I/O is transferred between the first module and the second module via the data bus. The data bus crosses a midplane that interconnects the modules. The second module stores data in the enclosure.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to storage systems, and more particularly to flexible designs for Network Accessed Storage systems. 
   BACKGROUND OF THE INVENTION 
   In the past, computer users have relied upon network file servers to provide distributed file services between the file server and a separate storage system. Files would be transferred from host computers over a network to the file server. The file server would then use any of several methods for storing the files on remote disk drives, usually via an I/O channel connection. Expensive servers such as Microsoft NT servers or Sun Solaris servers have been employed in front of expensive storage systems to provide this functionality. This has been found to be a relatively cumbersome and expensive solution. 
   Designers and manufacturers of storage systems have developed technology integrate these systems. The newer storage technology is known as a network accessed storage system, or NAS. A NAS is a storage system that connects directly to a network, such as a Gigabit Ethernet network. The NAS contains an integrated file server or controller for delivering distributed file services to hosts. File I/O is transferred over the network connection, and is cached in the NAS system and stored on the disk drives, and vice-versa. 
   Current NAS systems typically employ many different chassis holding equipment that performs various specific functions, making the NAS quite inflexible. Furthermore, the use of optical connectors and cables is often required to connect the various chassis. Though less expensive than remote server solutions, significant cost is incurred in providing a NAS because of these issues. There are now many storage customers that desire NAS functionality but want or need a lower cost system. A more flexible NAS system that can be manufactured and maintained at significantly lower costs than current systems is therefore highly desirable. 
   SUMMARY OF THE INVENTION 
   In accordance with the principles of the invention, a storage system includes a first enclosure having a first plurality of modules and non-volatile memory—for example, hard disk drives. Each of these modules is operable to convert file I/O to block I/O. A second enclosure includes a second plurality of modules and non-volatile memory. Each of these modules is operable to cause the block I/O to be stored on the non-volatile storage in either the first or second enclosure. Thus, the modules that perform block I/O storage can conveniently access storage that resides in the file I/O enclosure. 
   More particularly, each module of the first plurality of modules is coupled to a personality module that includes a network interface for connecting to a network—for example an Ethernet network—for transferring file I/O between the module and a host. 
   Each module of the first plurality of modules includes a channel I/O output for connecting to a first channel I/O medium—for example Fibre Channel—for transferring block I/O from the module to the second enclosure. In turn, each module of the second plurality of modules is coupled to a personality module that includes a first channel I/O input for connecting to the first channel I/O medium for transferring the block I/O from each module of the first plurality of modules. 
   Furthermore, each module of the second plurality of modules includes a channel I/O output for connecting to a second channel I/O medium—again for example Fibre Channel—for transferring block data between the module and the first enclosure. In turn, each module of the first plurality of modules includes a Channel I/O input for connecting to the second Channel I/O medium for transferring block I/O between the second plurality of modules and the non-volatile memory in the first enclosure. 
   According an implementation of this arrangement, the block I/O transfer modules can store data on disk drives installed in slots in the file I/O transfer modules, slots that would otherwise be empty. 
   In accordance with a different arrangement of the invention, a storage system includes a first enclosure including a first plurality of modules and non-volatile memory, for example hard disk drives. A first module of the first plurality of modules is operable to convert file I/O to block I/O. A second module of the first plurality of modules is operable to transfer block I/O to the non-volatile memory. The first and second modules are interconnected via a first data bus. Block I/O is transferred between the first module and the second module via the first data bus. 
   More particularly, the first plurality of modules and non-volatile memory are coupled to a first midplane. The first data bus crosses the first midplane and interconnects the first and second modules via the first midplane. 
   According to an implementation of this arrangement, NAS functionality is provided in a single enclosure. 
   These innovative storage systems, and methods for providing the same, provide a greatly needed low cost, compact NAS storage solution. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to facilitate a fuller understanding of the present invention, reference is now made to the appended drawings. These drawings should not be construed as limiting the present invention, but are intended to be exemplary only. 
       FIG. 1  is a representation of a rack mount server storage system. 
       FIG. 2  is a block diagram of a prior art implementation of a NAS system. 
       FIG. 3  is a block diagram of a NAS system implemented in accordance with the principles of the invention. 
       FIG. 4  is a block diagram of a NAS system implemented in accordance with further aspects of the invention. 
   

   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
   Referring to  FIG. 1 , there is shown a storage system  10  in which the principles of the invention may be employed. The storage system  10  includes a rack mount cabinet  12  that holds chassis or enclosures  14 . Many of the enclosures  14  include a portion for installing various types of modules, a portion where disk drives are installed, and a midplane that connects the modules to the disk drives and in some cases to each other. Various possible arrangements may place the disk drives in the front portion and the modules in the back portion, or vice-versa. The enclosures  14  may also include power supply units. Alternatively, such things as power supply enclosures and backup power supply enclosures, control modules or the like may exist in peripheral enclosures  14 . 
   In accordance with a prior art implementation of the storage system  10  of  FIG. 1 , the enclosures  14  may contain many different types of modules, all performing different functions, in order to implement a NAS (network accessed storage) system. Thus, many module and enclosure FRUs (field replaceable units) must be manufactured, shipped, and spared to utilize the storage system  10 . For example, consider an example of a prior art implementation of a NAS system as shown in  FIG. 2 . Each enclosure  16 ,  18 , and  20  includes different modules for performing different tasks. The bottom enclosure  16  includes dual NAS modules  22  for taking file I/O from a network  24  via NAS personality board  26 , converting that file I/O to block data, and forwarding the block data to the SAN (storage area network) enclosure  18  via Fibre Channel connections  28 . The Fibre Channel connections  28  consist of an optical cable connected to the NAS and SAN enclosures via optical connectors  30   a,b  and  32   a,b.    
   The middle SAN enclosure  18  includes dual processor modules  34  for caching block I/O data from the NAS enclosure  16 , converting the block I/O data to RAID (Redundant Array of Inexpensive Disks) format, and transferring the RAID data to/from disk drives  38 , access to which is controlled by one or more enclosures such as the top enclosure  20  labeled “DAE Chassis”. Optical Fibre Channel connectors  42 , coupled to Fibre Channel controllers  36 , connect the processor modules  34  via optical or copper cable  44  to the one or more DAE enclosures  20 . The DAE enclosure  20  includes dual control modules  40  for providing access to disk drives  38 . 
   For purposes of clarity, file I/O is a mechanism used to access and transfer “files” in accordance with different O/S types and transport techniques. For example, file I/O may use NFS or CIFS/SMB access protocols over TCP/IP Ethernet. File I/O is typically designed to avoid conflicts between file access so that files may be shared between users and between different OS types. Block I/O, on the other hand, is the basic mechanism for disk access, and moves data in block sizes (e.g. 16K, 128K, etc.) over SCSI, Fibre Channel, etc. I/O channels to and from the disk. So, for example, a file may be transferred as file I/O via TCP/IP, de-packetized, buffered, split into blocks, and transferred as block I/O (or further translated for fault tolerance purposes e.g. to RAID format) to the disks. 
   In order to store a file on the system of  FIG. 2 , the file is transferred over the network  24  to the NAS enclosure  16 . One of the modules  22  in the NAS enclosure  16  converts the file to block data and transfers the block data over Fibre Channel optical cables  28  to modules  34  in the SAN enclosure  18 . The SAN enclosure  18  then converts the block data to RAID format and transfers this RAID data over Fibre Channel optical cables  44  to disk storage  38  on a DAE enclosure such as  20 . The multiple chassis and optical connections traversed in order to move the file from the NAS enclosure  16  to the DAE enclosure  20  and store the file on disks  38  result in an overly expensive system. 
   In  FIG. 3  there is shown a NAS storage system incorporating the principles of the invention. Shown is an enclosure  50  including a pair of data mover modules  52  and disk drives  54 , as well as an enclosure  56  including a pair of storage processors  58  and disk drives  60 . Generally, file data enters the data movers  52  and is converted to block data, which is transferred to the storage processors  58 . The storage processors  58  then preferably translate the block data to RAID format and cause the data to be stored on disk drives  54  or  60 , or in larger systems, on disk drives located in other enclosures in the system. 
   Several aspects of the invention make the NAS system arrangement of  FIG. 3  very flexible and cost effective. First of all, an entire NAS system can be constructed from just the two enclosures shown. Note that disk drives are installed in the data mover enclosure  50  and in the storage processor enclosure  56 . As will be further described, the storage processors  58  can access all of these disk drives. Contrast this with the system of  FIG. 2 , wherein disk drives cannot be installed in the NAS and SAN chassis. The two enclosure solution is a cost effective entry level NAS solution that can be expanded by the addition of more DAE enclosures. 
   Furthermore, as will be further described, there are no optical cables or optical connectors required in the system of  FIG. 3 . All connections are implemented with copper cables or etch. This also results in significant cost savings. 
   Also, as can be seen, the data mover modules  52  and the storage processor modules  58  are substantially the same with the exception of personality boards  62  and  64 . This is advantageous and cost effective because the same base module can be used for different functions just by changing the personality board. Thus, many arrangements of storage systems can be constructed simply by arranging base modules and personality board FRUs (field replaceable units). 
   In accordance with a preferred embodiment of the system, an example of which shown in  FIG. 3 , the top enclosure  50  includes a pair of data mover modules  52  coupled in the back of the enclosure to a midplane  66 . Disk drives  54  reside in the front of the enclosure  50  and are also coupled to the midplane  66 . The data mover personality board  62  on each data mover module  52  includes a quad Gigabit Ethernet interface  68  for receiving file I/O over Ethernet network  69 . The quad Gigabit Ethernet interface  68  may be constructed for example of a pair of Broadcom 5704 dual Gigabit Ethernet transceivers. Though the preferred embodiment of the invention implements a quad Gigabit Ethernet Interface, it is understood that 10 Mbit Ethernet or another type of network connection, including newer higher speed network connections, could be implemented on the data mover personality board  62  without departing from the principles of the invention. The data mover personality board  62  also includes an I/O channel output port  70 . The I/O channel output port  70  is one of two I/O output ports that are coupled to input ports on one of the storage processor modules  58 , as will be further described. The I/O channel output ports are preferably coupled to Fibre Channel controllers  72  and implemented as Fibre Channel I/O output ports, but other I/O channel technologies such as SATA (Serial ATA), SAS (Serial Attached SCSI), etc. may be implemented without departing from the principles of the invention. 
   Further included on the data mover module  52  is a pair of I/O channel interfaces  74  and  76 , which again are preferably Fibre Channel interfaces. The I/O channel interface  74  is the other I/O channel output for transferring block I/O data to one of the storage processors  58  via HSSDC (“High Speed Serial Data Connector”)  78 , as will be further described. In accordance with an aspect of the invention, the other I/O channel interface  76  inputs block data from a storage processor  58  via an HSSDC  80 , as will also be described. In the Fibre Channel implementation shown, the I/O Channel interface  76  is connected to a Fibre Channel loop that interconnects the disk drives  54  and  60 . 
   The bottom enclosure  56  depicts a pair of storage processor modules  58  coupled to a midplane  82 . Disk drives  60  reside in the front of this enclosure  56  and are also coupled to the midplane  82 . Note that the Fibre Channel controllers  84  and I/O channel Interfaces  86  and  88  on each processor module  58  are arranged in the same manner as shown in the data mover module  52 . The only difference between the two modules lies in the storage processor personality board  90  and the configuration of the I/O channel ports. Each storage processor personality board  90  includes two I/O channel inputs  92 , for receiving block data from the data mover modules  52 . The Storage Processors  58  also include bus interface  94 . The bus interfaces  94  are interconnected by a bus  96  across the midplane  82 , and is used for communication between the storage processors  58 , as will be further described. The bus  96  may be a Fibre Channel peer-to-peer connection as shown, or could be an Infiniband™ connection, or a PCI connection, etc. Note that the bus interfaces  94  and bus  96  are not shown in the data mover modules  52 , because in this embodiment the data movers do not communicate with each other. The data mover modules  52  can include the bus interfaces  94  and simply not use them. This is preferable so that the base modules  52  and  58  are interchangeable. 
   The HSSDC Fibre Channel ports  86  and  88  on each storage processor module  58  are connected differently than those for the data mover modules  52 . In accordance with the invention, each Fibre Channel Port  88  outputs reconstructed block data (e.g. RAID data) from each storage processor  58  to the data mover module Fibre Channel input  76  for access to the disks  54  in the data mover enclosure  50 . The other Fibre Channel Port  86  outputs data to other disks that may be installed in the system. 
   The operation of the storage system including the data mover modules  52  and the storage processor modules  58  is now described. In order to store file data, the data is transferred via the network  69 , in the embodiment shown a Gigabit Ethernet network, from a host to the Gigabit Ethernet interface  68  on one of the data mover personality boards  62 . The data mover  52  converts the file data to block data. The data is transferred via the Fibre Channel Port  70  and/or  74  to the Fibre Channel port  92  on a storage processor module  58 . The block data received by the storage processor module  58  is stored in the storage processor for further transfer to disk. For purposes of fault tolerance, the block data is copied from one storage processor module  58  to the other storage processor module  58  via the bus interfaces  94  and bus  96 . The block data in each storage processor  58  may then be converted to RAID format and transferred via Fibre Channel Ports  86  to disks in another enclosure. Or, in accordance with an aspect of the invention, the reformatted block data may be transferred to disks  60  in the storage processor enclosure  56 , or transferred via the Fibre Channel Ports  88  to the Fibre Channel Port  76  on the data mover modules  52  and then to the disk drives  54  in the data mover module enclosure  50 . According to this aspect of the invention, the storage processor modules  58  can make use of disks installed in the storage processor enclosure  56  or the data mover enclosure  50 . Significant cost savings and system flexibility is thereby achieved. 
   In accordance with a further aspect of the invention, the system of  FIG. 3  requires no optics. That is, no optical cables are required, nor MIAs (electrical &lt;-&gt; optical media interface adapter), nor optical SFPs (small form factor pluggable connectors). Furthermore, no copper SFPs are required. The data mover personality boards  62  are arranged such that a copper cable can plug directly into the Fibre Channel port  70  on each data mover personality board  62 . Furthermore, the two Fibre Channel input ports  92  on the storage processor personality boards  64  also accept the copper cables. These optimizations are possible due to the elimination of the separate SAN enclosure between the data movers and disk enclosures as shown in the prior art  FIG. 2 , which required optical cables and connectors. The elimination of all optical cables and connectors provide even further cost savings. 
   In accordance with a different implementation of the invention, a data mover module and a storage processor module are installed within the same enclosure to provide an even lower cost, very compact NAS solution. Referring to  FIG. 4 , an enclosure  100  is shown to include a data mover module  102  that is the same as the data mover module  52  shown in  FIG. 3 . The storage processor module  104  is the same as the storage processor module  58  of  FIG. 3 . However, a cache memory board  106  replaces the storage processor personality board  64 . The cache memory board  106  is a battery backed up redundant memory. It reproduces the functionality previously described with regard to the system of  FIG. 3  wherein the block data stored in one storage processor module  58  was transferred via the midplane bus  96  for redundant storage in the other storage processor module  58 . This allows the midplane bus to be used for an innovative, cost effective purpose. 
   As shown, the data mover module  102  and the storage processor module  104  are coupled to a midplane  108  within the enclosure  100 . The data mover module  102  and the storage processor  104  include Fibre Channel controllers  116  and  118 , which are coupled via bus interfaces  110  to a midplane bus  112 . Disk drives  114  are coupled to the other side of the midplane  108 . In this compact NAS arrangement, file I/O enters the data mover module  102  via the quad Gigabit Ethernet interface as previously described. The file I/O is converted to block I/O, also as previously described. However, rather than exiting the data mover module  102  via a Fibre Channel port to reach the storage processor module  104  for disk storage, the block data is transferred across the midplane bus  112  via the bus interfaces  110  to the block storage cache memory  106  on the storage processor module  104 . It is then preferably converted to RAID format and either transferred via an internal Fibre Channel loop  122  for storage on the disk drives  114  in the enclosure  100 , or transferred out through the Fibre Channel ports  124  for storage on disk drives in another enclosure in the system. This system arrangement provides an entire NAS system in one enclosure. 
   Once again it should be noted that according to this architecture, the only difference between the data mover module  102  and the storage processor module  104  is the installation of either a data mover personality board or a cache memory board. The modules  102  and  104  can be shipped as the same FRU, being specialized in manufacturing or on site with the proper personality boards or cache memory boards. 
   It should be noted that in the examples shown in  FIGS. 3 and 4 , the chassis (enclosures) and midplanes are all exactly the same. This allows the base modules to be interchanged between chassis. The ability to implement a NAS storage system with such few enclosures, along with the ability to interchange all the described modules and enclosures and specify their functionality by adding or swapping in the proper personality boards or cache memory provides unparalleled flexibility in a NAS system. For example, a small enterprise organization might begin with a chassis containing only the enclosure of  FIG. 4 , along with the necessary power supply modules if required. As the organization grows, and increased storage space and fault tolerance is required, a new enclosure could be added. The existing enclosure, configured as shown in  FIG. 4 , could be changed to either the dual data mover module enclosure  50  of  FIG. 3  or the dual storage processor enclosure  56  of  FIG. 3 . Say for example the modules in the existing enclosure are converted to storage processor modules  58  by installation of storage processor personality modules  90 . Dual modules would then be installed in the new enclosure and configured, via installation of data mover personality modules, as data mover modules  52 , the enclosure  50  including disk drives  54 . Now the system has been converted to to the larger, fault tolerant innovative system of  FIG. 3  while still requiring only two enclosures and no optics. More disk drive enclosures can be added as storage capacity requirements increase. It can be seen that, as the NAS system grows, many different configurations can be achieved by installing more of the same module FRUs and changing the functionality of existing module FRUs via the installation of particular personality boards. 
   The present invention is not to be limited in scope by the specific embodiments described herein. Indeed, various modifications of the present invention, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such modifications are intended to fall within the scope of the invention. Further, although aspects of the present invention have been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present invention can be beneficially implemented in any number of environments for any number of purposes.