Incremental snapshot based technique on paged translation systems

Patent metadata

Field	Value
Publication number	US-2018329637-A1
Application number	US-201816041713-A
Country	US
Kind code	A1
Filing date	Jul 20, 2018
Priority date	Jun 29, 2016
Publication date	Nov 15, 2018
Grant date	—

Abstract

A data storage apparatus that includes a storage device and a processor coupled to the storage device. The processor is configured to receive in a memory, a first logical block entry for a first dump group and a second logical block entry for a second dump group; store in a reverse translation table, the first logical block entry for the first dump group and the second logical block entry for the second dump group; determine a first sequence number associated with the stored first logical block entry and the stored second logical block entry in the reverse translation table, wherein the first sequence number is a snapshot marker that determines a timestamp associated with the first logical block and the second logical block; and persist the first logical block entry for the first dump group in the storage device.

First claim

What is claimed is:

1 . A method comprising:
receiving, in a memory, a first logical block entry for a first dump group and a second logical block entry for a second dump group; storing, in a reverse translation table, the first logical block entry for the first dump group and the second logical block entry for the second dump group; determining a first sequence number associated with the stored first logical block entry and the stored second logical block entry in the reverse translation table; and persisting the first logical block entry for the first dump group in a storage device.

2 . The method of claim 1 , further comprising:
receiving, in the memory, a third logical block entry for the first dump group and a fourth logical block entry for the second dump group; storing, in the reverse translation table, the third logical block entry for the first dump group and the fourth logical block entry for the second dump group; determining a second sequence number associated with the stored third logical block entry and the stored fourth logical block entry in the reverse translation table; and persisting, in the storage device, the second logical block entry for the second dump group and the fourth logical block entry for the second dump group.

3 . The method of claim 2 , further comprising reclaiming memory corresponding to the second dump group after determining that the second dump group is persisted in the storage device.

4 . The method of claim 2 , further comprising:
receiving a request to reconstruct a dump group table for the first dump group and the second dump group; retrieving the first sequence number as a snapshot marker for the first dump group and the second sequence number as a snapshot marker for the second dump group; identifying that the second sequence number is greater than the first sequence number; and retrieving from an additional source, the third logical block entry for the first dump group associated with the second sequence number.

5 . The method of claim 4 , wherein the additional source includes a reverse translation map stored in the memory or a meta-log journal stored in the memory.

6 . A data storage apparatus comprising:
a storage device; and a processor coupled to the storage device and configured to:
receive, in a memory, a first logical block entry for a first dump group and a second logical block entry for a second dump group;
store, in a reverse translation table, the first logical block entry for the first dump group and the second logical block entry for the second dump group;
determine a first sequence number associated with the stored first logical block entry and the stored second logical block entry in the reverse translation table, wherein the first sequence number is a snapshot marker that determines a timestamp associated with the first logical block and the second logical block; and
persist the first logical block entry for the first dump group in the storage device.

7 . The data storage apparatus of claim 6 , wherein the processor is further configured to:
receive, in the memory, a third logical block entry for the first dump group and a fourth logical block entry for the second dump group; store, in the reverse translation table, the third logical block entry for the first dump group and the fourth logical block entry for the second dump group; determine a second sequence number associated with the stored third logical block entry and the stored fourth logical block entry in the reverse translation table; and persist, in the storage device, the second logical block entry for the second dump group and the fourth logical block entry for the second dump group.

8 . The data storage apparatus of claim 7 , wherein the processor is further configured to reclaim memory corresponding to the second dump group after determining that the second dump group is persisted in the in the storage device.

9 . The data storage apparatus of claim 7 , wherein the processor is further configured to:
receive a request to reconstruct a dump group table for the first dump group and the second dump group; retrieve the first sequence number as a snapshot marker for the first dump group and the second sequence number as a snapshot marker for the second dump group; determine that the second sequence number is greater than the first sequence number; and retrieve, from an additional source, the third logical block entry for the first dump group associated with the second sequence number.

10 . The data storage apparatus of claim 9 , wherein the first sequence number and the second sequence number are retrieved from a timestamp log stored in the memory.

11 . A data storage apparatus comprising:
a storage device; and a processor coupled to the storage device and configured to:
receive a request to reconstruct a dump group table for a first dump group and a second dump group;
retrieve a first sequence number as a snapshot marker for the first dump group and a second sequence number as a snapshot marker for the second dump group;
determine that the second sequence number is greater than the first sequence number; and
retrieve, from an additional source, a logical block entry for the first dump group associated with the second sequence number.

12 . The data storage apparatus of claim 11 , wherein the logical block entry is a third logical block entry, the first dump group comprising a first logical block entry and the third logical block entry.

13 . The data storage apparatus of claim 12 , wherein the second dump group includes a second logical block entry and a fourth logical block entry.

14 . The data storage apparatus of claim 11 , wherein the first sequence number is a snapshot marker that determines a timestamp associated with a first logical block and a second logical block.

15 . The data storage apparatus of claim 11 , wherein the request to reconstruct the dump group table for the first dump group and the second dump group is received after a second logical block entry for the second dump group and a fourth logical block entry for the second dump group have been persisted in the storage device.

16 . The data storage apparatus of claim 11 , wherein the request to reconstruct is received after an unplanned shutdown and device restart.

17 . The data storage apparatus of claim 11 , wherein the first sequence number and the second sequence number are retrieved from a timestamp log stored in a memory coupled to the processor.

18 . The data storage apparatus of claim 11 , wherein the logical block entry for the first dump group is retrieved from a reverse translation map stored in a memory coupled to the processor.

19 . The data storage apparatus of claim 11 , wherein the logical block entry for the first dump group is retrieved from a meta-log journal stored in a memory coupled to the processor.

20 . The data storage apparatus of claim 11 , wherein the second sequence number is associated with a stored third logical block entry and a stored fourth logical block entry in a reverse translation table.

Assignees

• Western Digital Tech Inc

Inventors

• Battaje Ajith Kumar
• Goel Tanay
• Mishra Rajendra Prasad

Classifications

• G06F2212/68

  Details of translation look-aside buffer [TLB] · CPC title

• G06F3/065

  Replication mechanisms · CPC title

• G06F2212/702

  Conservative garbage collection · CPC title

• G06F2212/1044

  Space efficiency improvement · CPC title

• G06F12/1027

  using associative or pseudo-associative address translation means, e.g. translation look-aside buffer [TLB] · CPC title