Managing snapshots in storage systems

• US 20080104139A1
• Filed: 10/26/2006
• Published: 05/01/2008
• Est. Priority Date: 10/26/2006
• Status: Active Grant

• Current Assignee: Snowflake, Inc.
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Xu, Xia, Lindemann, Aaron
• Granted Patent: US 8,046,534 B2
• Time in Patent Office: Days
• US Class Current: 707/202
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

Embodiments include methods, apparatus, and systems for managing snapshots in storage systems. One method includes logically linking a plurality of snapshots to a logical disk in a storage network; and splitting the snapshots from the logical disk to form a snapshot tree that includes the snapshots split from the logical disk.

Claims

1. ) A method, comprising:

logically linking a plurality of snapshots to a logical disk in a storage network; and

splitting the snapshots from the logical disk to form a snapshot tree that includes the snapshots split from the logical disk.

2. ) The method of claim 1 further comprising, splitting the snapshot tree into plural subtrees, each subtree having at least one snapshot previously associated with the logical disk.

3. ) The method of claim 1 further comprising, maintaining a point-in-time copy of data for the snapshots after splitting the snapshots from the logical disk.

4. ) The method of claim 1 further comprising:

assigning a first redundant array of inexpensive disks (RAID) level type to the logical disk;

assigning a second RAID level, different than the first RAID level, to the snapshot tree.

5. ) The method of claim 1 further comprising:

storing the snapshot tree;

adding new snapshots to the logical disk after the snapshot tree is formed.

6. ) The method of claim 1 further comprising, splitting the snapshots from the logical disk without deleting any of the snapshots.

7. ) The method of claim 1 further comprising, creating a mirror clone of the logical disk with the snapshots without deleting any of the snapshots.

8. ) A computer readable medium having instructions for causing a computer to execute a method, comprising:

linking plural snapshots to a logical disk in a storage network, each snapshot including a copy of data at a different point in time; and

splitting at least one snapshot from the logical disk to form a snapshot tree without deleting any of the plural snapshots.

9. ) The computer readable medium of claim 8 further comprising:

creating redundant array of inexpensive disks (RAID) level 0 for the plural snapshots linked to the logical disk;

creating RAID level 5 for the snapshot tree.

10. ) The computer readable medium of claim 8 further comprising, creating a mirror clone of the logical disk without deleting any of the plural snapshots.

11. ) The computer readable medium of claim 8 further comprising, storing the snapshot tree as a standalone tree that is not logically linked to the logical disk.

12. ) The computer readable medium of claim 8 further comprising, preserving point-in-time copies of all snapshots after splitting of the at least one snapshot from the logical disk.

13. ) The computer readable medium of claim 8 further comprising, splitting at least a second snapshot from the logical disk to form a second snapshot tree without deleting any of the plural snapshots.

14. ) The computer readable medium of claim 8 further comprising, serially linking the plural snapshots together.

15. ) The computer readable medium of claim 8 further comprising, avoiding an overcommit by verifying enough memory space exists before initiating splitting of the at least one snapshot from the logical disk.

16. ) A storage device system, comprising:

a memory for storing logic instructions; and

a processor for executing the logic instructions to;

link plural snapshots to a logical disk in a storage network, each snapshot including a copy of data at a different point in time; and

split snapshots from the logical disk to result in (1) the logical disk with no snapshots and (2) a snapshot tree with the plural snapshots.

17. ) The computer system of claim 16, wherein the processor further executes the logic instructions to split the snapshot tree into plural snapshot trees, each snapshot tree having at least one snapshot previously linked to the logical disk.

18. ) The computer system of claim 16, wherein the processor further executes the logic instructions to split the snapshots from the logical disk without deleting any of the snapshots.

19. ) The computer system of claim 16, wherein the processor further executes the logic instructions to add new snapshots to the logical disk after the snapshots are split from the logical disk.

20. ) The computer system of claim 16, wherein the processor further executes the logic instructions to assign different redundant array of inexpensive disk (RAID) levels to each of the (1) the logical disk with no snapshots and (2) the snapshot tree with the plural snapshots.