Enhanced copy-on-write operation for solid state drives

• US 8,868,869 B2
• Filed: 08/08/2011
• Issued: 10/21/2014
• Est. Priority Date: 08/08/2011
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Jones, Carl Evan, Roy, Subhojit, Fiske, Rahul
• Primary Examiner(s): Elmore, Stephen
• Assistant Examiner(s): GIARDINO JR, MARK A
• Application Number:
  US13/205,493
• Publication Number:
  US 20130042049A1
• Time in Patent Office: 1,170 Days
• Field of Search: 711/103, 711/114, 711/162, 711/165, 707/639
• US Class Current: 711/165
• CPC Class Codes: G06F 11/1446 Point-in-time backing up or restoration of persistent data
• CPC Class Codes: G06F 12/02 Addressing or allocation; Relocation program address sequencing G06F9/00; arrangements for selecting an address in a digital store G11C8/00
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 3/065 Replication mechanisms

Abstract

A method for increasing the efficiency of a “copy-on-write” operation performed on an SSD to extend the life of the SSD is disclosed herein. In one embodiment, such a method includes receiving a first logical address specifying a logical location where new data should be written to an SSD. The first logical address maps to a first physical location, storing original data, on the SSD. The method further receives a second logical address specifying a logical location where the original data should be available on the SSD. The second logical address maps to a second physical location on the SSD. To efficiently perform the copy-on-write operation, the method writes the new data to a new physical location on the SSD, maps the first logical address to the new physical location, and maps the second logical address to the first physical location. A corresponding apparatus is also disclosed.

Claims

1. A solid state drive (SSD) configured to efficiently perform a “

copy-on-write”

operation, the solid state drive comprising;

an SSD controller configured to receive an enhanced copy-on-write (ECOW) command comprising arguments;

new data to be written to the SSD;

a first logical address specifying a logical location where the new data should be written to the SSD, the first logical address mapping to a first physical location, storing original data, on the SSD; and

a second logical address specifying a logical location where the original data should be available on the SSD, the second logical address mapping to a second physical location on the SSD;

the SSD controller further configured to perform the following in response to receiving the ECOW command;

retrieve a new physical location from a free block list maintained by a wear-leveling algorithm of the SSD controller;

write the new data to the new physical location;

map the first logical address to the new physical location; and

map the second logical address to the first physical location.

2. The solid state drive of claim 1, wherein the SSD controller is further configured to modify a mapping table such that the second logical address maps to the first physical location.

3. The solid state drive of claim 1, wherein the second logical address identifies a scratch space on the SSD where the original data should be available on the SSD.

4. The solid state drive of claim 3, wherein the original data is copied from the scratch space on the SSD to a different SSD.

5. The solid state drive of claim 1, wherein receiving the new data, first logical address, and second logical address comprises receiving the new data, first logical address, and second logical address from a storage virtualization product.

6. The solid state drive of claim 1, wherein the first and second logical addresses are logical block addresses.

7. The solid state drive of claim 1, wherein the wear-leveling algorithm ensures that memory cells in the SSD are utilized substantially uniformly.