Storage virtualization by layering virtual disk objects on a file system

• US 20040030822A1
• Filed: 08/09/2002
• Published: 02/12/2004
• Est. Priority Date: 08/09/2002
• Status: Active Grant

• Current Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Original Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Inventors: Pawlowski, Brian, Srinivasan, Mohan, Rajan, Vijayan, Lewis, Blake H., Bolen, David Brittain
• Granted Patent: US 7,107,385 B2
• Time in Patent Office: Days
• US Class Current: 711/4
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0614 Improving the reliability of storage systems
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A storage virtualization selection technique “automates” a virtualization selection process to create virtual disk (vdisk) storage objects over a volume of a file system implemented by a storage operating system of a multi-protocol storage appliance. The file system provides a virtualization system that aggregates physical storage of a set of disks or portions (e.g., extents) of disks into a pool of blocks that can be dynamically allocated to form a vdisk. The file system also provides reliability guarantees for the vdisks in accordance with its underlying architecture. That is, the file system organizes its storage within volumes created among the managed disks. The vdisk is thereafter created as a storage object within a volume and, thus, inherits the underlying reliability configuration associated with that volume. The portions are aggregated and allocated as a vdisk with reliability guarantees in response to a request to create the vdisk from a user of the storage appliance and without further user involvement.

Claims

1. A method for creating a virtual disk (vdisk) of a file system implemented by a storage operating system of a storage system, the method comprising the steps of:

aggregating physical storage of portions of disks into a pool of blocks;

dynamically allocating the portions of the disks to form a vdisk; and

providing reliability guarantees for the vdisk in accordance with an underlying architecture of the file system,

wherein the steps of aggregating, dynamically allocating and providing are performed in response to a user request to create the vdisk and without further user involvement.

2. The method of claim 1 wherein the portions of the disks are extents.

3. The method of claim 1 further comprising the steps of:

organizing storage of the file system within volumes created among the managed disks;

creating the vdisk as a storage object within one of the volumes; and

inheriting, on behalf of the vdisk, the underlying reliability configuration associated with the volume.

4. The method of claim 1 further comprising the step of one of growing and shrinking the vdisk under user control while preserving block and network attached storage (NAS) multi-protocol access to application data stored in the vdisk.

5. A system for creating virtual disks (vdisks) on a storage system, the system comprising:

a storage operating system resident in a memory of the storage system and invoking storage operations in support of a file system configured to logically organize information as a hierarchical structure of vdisks within a volume of the storage system, each vdisk stored in the volume as a representation embodying a logical unit number (lun) inode functioning as a main container for storing data associated with the vdisk and at least one stream inode that functions as a persistent store for storing various attributes, wherein the lun inode and at least one associated stream inode are managed as a single encapsulated storage object within the file system.

6. The system of claim 5 wherein the at least one stream inode is an attributes inode.

7. The system of claim 6 wherein the lun inode comprises a data section that includes one of data and pointers referencing data blocks on the disk used to store the data.

8. The system of claim 7 wherein the lun inode further comprises a metadata section containing a type and size of the vdisk, the metadata section further containing a flag_stream flag that identifies the lun inode as a data container and one or more streams.

9. The system of claim 6 wherein the attributes inode comprises a data section that functions as a persistent store for holding various named attributes associated with the vdisk, the attributes including information that allows the vdisk to be exported as a lun to clients of the storage system and that enable management of the vdisk as a single disk object in relation to the clients.

10. The system of claim 9 wherein the attributes further comprise at least one of serial number, space reservation, state and geometry information.

11. The system of claim 5 wherein each vdisk further embodies a lunmap inode that includes a data section functioning as a persistent store for holding a list of name-value pairs and a persistent reservations inode that includes a data section functioning as a persistent store for holding a list of persistent reservation records.

12. The system of claim 11 wherein the persistent reservation records provide ownership and access information relating to the vdisk.

13. The system of claim 5 further comprising a per-volume data structure stored in a metadata file that is used to optimize location determination and initialization of the vdisks in a volume.

14. The system of claim 13 wherein the data structure is a vdisk table of contents data structure comprising one or more records including file entry information that can be dynamically reconstructed from information stored in an encapsulated storage object representing the vdisk.

15. The system of claim 14 wherein each record includes file entries comprising:

a file identifier on the volume;

a generation number of the lun inode; and

directory information including a file block number in a parent directory containing an entry for the vdisk, along with an index of directory entries in a parent directory block.

16. The system of claim 5 wherein the vdisk encapsulates security information that restricts access to the vdisk, thereby providing multi-protocol access over either network attached storage or storage area network protocols while preserving data integrity.

17. A method for automating a selection process to create a virtual disk (vdisk) of a file system implemented by a storage operating system of a multi-protocol storage appliance, the method comprising the steps of:

issuing a lun create command through an administrative interface of the multi-protocol storage appliance, the lun create command specifying a size of the vdisk and a path descriptor of a location of the vdisk; and

creating the vdisk in response to the lun create command.

18. The method of claim 17 further comprising the step of resizing the vdisk using information pertaining to geometry of the vdisk.

19. The method of claim 18 wherein the step of resizing further comprises the step of algorithmically converting the specified vdisk size to the geometry information, the geometry information providing a limiting factor on how large the vdisk can be resized.

20. The method of claim 19 wherein the geometry information is cylinder size.

21. A method for creating a virtual disk (vdisk) of a file system implemented by a storage operating system of a multi-protocol storage appliance, the method comprising the steps of:

issuing a vdisk create command through an administrative interface of the multi-protocol storage appliance, the vdisk create command specifying a size of the vdisk and a path descriptor of a location of the vdisk;

creating a file inode associated with the vdisk, the file inode having a regular file type;

creating a stream inode for storing attributes associated with the vdisk;

populating the stream inode with attributes; and

converting the file type of the file inode from regular to vdisk, thereby creating the vdisk.

22. The method of claim 21 further comprising the steps of, after the step of issuing:

checking the specified size and path descriptor at a virtualization system of the multi-protocol storage appliance;

if the path descriptor and size do not check, aborting creation of the vdisk; and

if the path descriptor and size do check, proceeding to the step of creating a file inode.

23. The method of claim 21 wherein the step of creating a file inode further comprises the step of setting the specified size for the file inode.

24. The method of claim 21 wherein the attributes include a state of the vdisk, permissions for sharing the vdisk over network file system protocols and inquiry information.

25. The method of claim 24 wherein the step of populating further comprises the steps of:

setting a file owner and group identification parameter for use when the vdisk is exported over the network file system protocols; and

setting space reservation guarantees so that write operations to the vdisk do not fail.

26. A system for automating a selection process to create virtual disks (vdisks) on a storage appliance, the system comprising:

a processor;

a memory coupled to the processor and having locations addressable by the processor;

at least one disk coupled to the memory and processor; and

a storage operating system resident in the memory and invoking storage operations in support of a file system configured to logically organize information as a hierarchical structure of vdisks on the disk, each vdisk stored on the disk as a representation embodying a logical unit number (lun) inode functioning as a main container for storing data associated with the vdisk and an attributes inode that functions as a persistent store for storing various attributes, wherein the lun inode and attributes inode are managed as a single encapsulated storage object within the file system.

27. A method for automating a storage virtualization process to create a virtual disk (vdisk) of a file system implemented by a storage operating system of a storage appliance, the method comprising the steps of:

issuing a vdisk create command through an administrative interface of the storage appliance, the vdisk create command specifying a size of the vdisk and a path descriptor of a location of the vdisk;

creating a file inode associated with the vdisk, the file inode having a vdisk file type;

creating a stream inode for storing attributes associated with the vdisk; and

populating the stream inode with attributes.

28. The method of claim 27 wherein the vdisk create command is a lun create command.

29. Apparatus for layering a virtual disk (vdisk) on a file system implemented by a storage operating system of a multi-protocol storage appliance, the apparatus comprising:

means for aggregating physical storage of portions of disks into a pool of blocks;

means for dynamically allocating the portions of the disks to form a vdisk; and

means for providing reliability guarantees for the vdisk in accordance with an underlying architecture of the file system,

wherein the means for aggregating, dynamically allocating and providing are performed in response to a user request to create the vdisk and without further user involvement.

30. A computer readable medium containing executable program instructions for storage virtualization of a virtual disk (vdisk) of a file system implemented by a storage operating system of a storage system, the executable program instructions comprising program instructions for:

issuing a lun create command through an administrative interface of the storage system, the lun create command specifying a size of the vdisk and a path descriptor of a location of the vdisk; and

creating a vdisk in response to the lun create command.

31. A method for storage virtualization of a virtual disk (vdisk) on a file system implemented by a storage operating system of a multi-protocol storage appliance, the method comprising the steps of:

providing an encapsulated storage object of the file system, the encapsulated storage object including a container for storing data associated with the vdisk and a persistent store for storing attributes associated with the vdisk; and

accessing the encapsulated storage object as a logical unit number.