Managing common storage by allowing delayed allocation of storage after reclaiming reclaimable space in a logical volume

• US 7,702,873 B2
• Filed: 04/25/2005
• Issued: 04/20/2010
• Est. Priority Date: 04/25/2005
• Status: Active Grant

• Current Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Original Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Inventors: Lango, Jason A., Zheng, Qinghua, Griess, Peter, Grunwald, David A.
• Primary Examiner(s): Shah; Sanjiv
• Assistant Examiner(s): Ayash; Marwan
• Application Number:
  US11/114,518
• Publication Number:
  US 20060242382A1
• Time in Patent Office: 1,821 Days
• Field of Search: 711/170, 711/171, 711/172, 707/205, 707/206
• US Class Current: 711/170
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• 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]

Abstract

An apparatus and method for managing of common storage in a storage system is disclosed. In one embodiment, a storage system receives a request to set a space reservation for a volume associated with a logical aggregation of physical storage. In response, the storage system sets the space reservation to indicate that the logical aggregation of physical storage is to provide a specified amount of space to the volume. In one embodiment, space within the logical aggregation of physical storage is automatically reclaimed to set a delayed space reservation if the amount of unused space within the logical aggregation of physical storage is insufficient to set the space reservation. In one embodiment, the volume is either a space-reclaimable volume or a non-space-reclaimable volume. Other embodiments are described and claimed.

Claims

1. A method comprising:

receiving, at a storage server, an indication to set a space reservation for a volume associated with a logical aggregation of physical storage, wherein the logical aggregation of physical storage provides an abstraction layer between the volume and a physical storage;

reclaiming space from one or more space-reclaimable volumes that organize space within the logical aggregation of physical storage if the logical aggregation of physical storage does not have enough free space to reserve a specified amount of storage space for the volume to provide a requested storage capacity for the volume according to the space reservation, wherein reclaiming space includes

determining an amount of space-reclaimable available from the one or more space-reclaimable volumes if the volume accepts a delayed space reservation, and

delaying setting of the space reservation for the volume until a sufficient amount of space is reclaimed from the one or more space-reclaimable volumes, wherein the delaying includes

detecting a plurality of allocated, unreserved blocks of the one or more space-reclaimable volumes,

performing at least one of truncating and compressing data in the detected blocks to create a free space reserve, and

reserving the specified amount of the logical aggregation of physical storage for the volume as a delayed space reservation according to the free space reserve; and

granting the delayed space reservation for the volume until the sufficient amount of space is reclaimed from the one or more space-reclaimable volumes associated with the logical aggregation of physical storage to provide the requested storage capacity for the volume,

wherein the logical aggregation of physical storage provides a common pool of physical storage shared between at least one space-reclaimable volume and at least one non-space-reclaimable volume and the sufficient amount of storage space to provide a requested storage capacity for the volume is reclaimed from the space-reclaimable volume.

2. The method of claim 1, further comprising:

setting the delayed space reservation for the volume to reserve the specified amount of the logical aggregation of physical storage responsive, at least in part, to the reclaiming of space within the logical aggregation of physical storage, wherein the delayed space reservation specifies that the logical aggregation of physical storage is to provide the specified amount of space to the volume.

3. The method of claim 1, wherein receiving the indication to set the space reservation comprises at least one of:

receiving an indication to create the volume; and

receiving an indication to set a space reservation for a previously-created volume.

4. The method of claim 1, wherein receiving the indication to set the space reservation further comprises:

determining a value R representing a number of blocks within the logical aggregation of physical storage that are reserved for a space reservation;

determining a value U representing a number of used blocks within the logical aggregation of physical storage;

determining a value N representing a number of non-reclaimable metadata blocks within the logical aggregation of physical storage; and

calculating the number of reclaimable blocks RB, wherein RB is based, at least in part, on R, N and U.

5. The method of claim 1, wherein receiving the indication to set the space reservation further comprises:

detecting that the amount of free space within the logical aggregation of physical storage is insufficient to reserve the specified amount if the number of free blocks within the logical aggregation of physical storage is less than the specified amount;

determining an amount of space-reclaimable available from at least one caching volume associated with the logical aggregation of physical storage; and

if the amount of space-reclaimable within the caching volume associated with the logical aggregation of physical storage is insufficient to enable the space reservation, initiate the delayed space reservation for the volume.

6. The method of claim 1, wherein the logical aggregation of physical storage is a logical aggregation of one or more redundant array of inexpensive disks (RAID) groups.

7. The method of claim 1, wherein delaying setting of the space reservation further comprises:

increasing a partial space reservation of the one or more space-reclaimable volumes to set a space reservation for the one or more space-reclaimable volumes to provide a requested storage capacity for the one or more space-reclaimable volumes;

and

decreasing the space reservation of the one or more space-reclaimable volumes to a previous level.

8. An article of manufacture comprising:

a machine-readable storage medium encoded with instructions that, when executed by an apparatus, cause the apparatus to;

detect that an amount of free space within a logical aggregation of physical storage is insufficient to set a space reservation for a volume associated with the logical aggregation of physical storage, wherein the logical aggregation of physical storage provides an abstraction layer between the volume and a physical storage;

determine an amount of space-reclaimable available from one or more space-reclaimable volumes associated with the logical aggregation of physical storage;

if the amount of space-reclaimable within the space-reclaimable volume associated with the logical aggregation of physical storage is insufficient to enable the space reservation, reclaim space from the one or more space-reclaimable volumes associated with the logical aggregation of physical storage, and grant a delayed space reservation for the volume until a sufficient amount of space is reclaimed from the one or more space-reclaimable volumes wherein reclaiming space includes

detecting a plurality of allocated, unreserved blocks of the one or more space-reclaimable volumes,

performing at least one of truncating and compressing data in the detected blocks to create a free space reserve, and

reserving the specified amount of the logical aggregation of physical storage for the volume as a delayed space reservation according to the free space reserve; and

grant the space reservation to provide a requested storage capacity for the volume responsive, at least in part, to the delayed space reservation,

wherein the logical aggregation of physical storage provides a common pool of physical storage shared between the at least one space-reclaimable volume and at least one non-space-reclaimable volume.

9. The article of manufacture of claim 8, wherein the instructions that, when executed by the apparatus, cause the apparatus to detect that there is an insufficient amount of free space within the logical aggregation of physical storage further cause the apparatus to:

receive an indication to set a space reservation for the volume associated with the logical aggregation of physical storage; and

determine whether the amount of free space within the logical aggregation of physical storage is insufficient to reserve the specified amount of the logical aggregation of physical storage for the volume according to the space reservation.

10. The article of manufacture of claim 9, wherein the instructions that, when executed by the apparatus, cause the apparatus to receive the indication to set the space reservation for the volume cause the apparatus to perform at least one of:

receive an indication to create the volume; and

receive an indication to set a space reservation for a previously-created volume.

11. The article of manufacture of claim 8, wherein the instructions that, when executed by the apparatus, cause the apparatus to delay setting of the space reservation cause the apparatus to:

detect that the volume is enabled for a delayed space reservation; and

reclaim space within the logical aggregation of physical storage to reserve the specified amount of space for the volume according to the space reservation.

12. The article of manufacture of claim 8, wherein the instructions that, when executed by the apparatus, cause the apparatus to determine an amount of space-reclaimable cause the apparatus to:

determine a value R representing a number of blocks within the logical aggregation of physical storage that are reserved for a space reservation;

determine a value U representing a number of used blocks within the logical aggregation of physical storage;

determine a value N representing a number of non-reclaimable metadata blocks within the logical aggregation of physical storage; and

calculate the number of reclaimable blocks RB, wherein RB is based, at least in part, on R, N and U.

13. The article of manufacture of claim 11, wherein the instructions that, when executed by the apparatus, cause the apparatus to reclaim space within the logical aggregation of physical storage cause the apparatus to:

increase a partial space reservation of the one or more space-reclaimable volumes to set a space reservation for the one or more space-reclaimable volumes to a current amount of space allocated to the one or more space-reclaimable volumes;

and

decrease the space reservation of the one or more space-reclaimable volumes to a previous level.

14. A method comprising:

in a storage server, allocating space within a logical aggregation of physical storage between at least two volumes associated with the logical aggregation of physical storage, wherein the logical aggregation of physical storage provides an abstraction layer between the at least two volumes and a physical storage;

setting a partial space reservation for each of the volumes, wherein the partial space reservation specifies that the logical aggregation of physical storage is to provide a specified amount of reserved space to each volume that is less than a capacity of each volume;

detecting that a relative capacity of a first volume from the at least two volumes is below a minimum relative capacity level; and

reclaiming space used by a second volume from the at least two volumes for the first volume if a first volume usage level within the logical aggregation of physical storage is below a predetermined minimum usage level and a second volume usage level within the logical aggregation of physical storage exceeds a predetermined maximum usage level,

wherein the logical aggregation of physical storage provides a common pool of physical storage shared between at least one space-reclaimable volume and at least one non-space-reclaimable volume and the sufficient amount of storage space to provide a requested storage capacity for the volume is reclaimed from the space-reclaimable volume, and

wherein reclaiming space includes,

detecting a plurality of allocated, unreserved blocks of the second volume;

truncating the detected blocks to create a free space reserve for the first volume;

allocating the free space reserve to the first volume.

15. The method of claim 14, wherein the relative capacity of the first volume is a value representing a maximum amount of data currently available for storage within the first volume according to available space within the local aggregation of physical storage.

16. The method of claim 14, wherein reclaiming space used by the second volume comprises:

increasing a space reservation of the second volume to a current amount of space allocated to the second volume;

and

decreasing the space reservation of the second volume to a previous level.

17. The method of claim 14, wherein the first volume is a non-caching volume and the second volume is a caching volume.

18. An apparatus comprising:

a storage server to maintain a hierarchical structure of data stored in an array of physical storage devices and to service read and write requests from one or more clients relating to data stored in the array of physical storage devices;

one or more non-space-reclaimable volumes, each sharing a common pool of physical storage provided by the array of storage devices, wherein each non-space-reclaimable volume is a logical data container;

one or more space-reclaimable volumes, each sharing the common pool of physical storage provided by the array of storage devices, wherein each space-reclaimable volume is a logical data container for temporary storage of client data and configured to enable the reclaiming of space within the respective space-reclaimable volume;

a logical aggregation of physical storage to provide an abstraction layer between the one or more non-space-reclaimable volumes, the one or more space-reclaimable volumes and the array of storage devices; and

a storage allocation module to monitor and adjust allocation of the logical aggregation of physical storage between the non-space-reclaimable volumes and the space-reclaimable volumes, the storage allocation module including a delayed space reservation module to reclaim space from one or more space-reclaimable volumes associated with the logical aggregation of physical storage if the logical aggregation of physical storage does not have enough free space to reserve a specified amount of storage space for a volume to provide a requested storage capacity for the volume according to a space reservation for the volume, wherein reclaiming space includes

determining an amount of space-reclaimable available from one or more space-reclaimable volumes if the volume accepts a delayed space reservation, and

delaying setting of the space reservation for the volume until a sufficient amount of space is reclaimed from the one or more space-reclaimable volumes, wherein the delaying includes

detecting a plurality of allocated, unreserved blocks of the one or more space-reclaimable volumes,

performing at least one of truncating and compressing data in the detected blocks to create a free space reserve, and

reserving the specified amount of the logical aggregation of physical storage for the volume as a delayed space reservation according to the free space reserve, and

the storage allocation module to further set a delayed space reservation for the volume responsive, at least in part, to reclaiming of space from at least the one or more space-reclaimable volumes to provide the requested storage capacity for the volume,

wherein the logical aggregation of physical storage provides a common pool of physical storage shared between at least one space-reclaimable volume and at least one non-space-reclaimable volume and the sufficient amount of storage space to provide a requested storage capacity for the volume is reclaimed from the space-reclaimable volume, and

wherein reclaiming space includes at least one of;

truncating and compressing data contained in the one or more space-reclaimable volumes.

19. The apparatus of claim 18, wherein the storage allocation module further comprises an aggregate rebalancing module to detect that a relative capacity of a first volume is below a minimum relative capacity level and to reclaim space used by a second volume if a first volume usage level within the logical aggregation of physical storage is below a predetermined minimum usage level and a second volume usage level within the logical aggregation of physical storage exceeds a predetermined maximum usage level.

20. The apparatus of claim 19, wherein the first volume is a non-caching volume and the second volume is a caching volume.