ENHANCED COPY-ON-WRITE OPERATION FOR SOLID STATE DRIVES

• US 20130238869A1
• Filed: 03/15/2013
• Published: 09/12/2013
• 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
• Granted Patent: US 8,972,681 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• 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 method for increasing the efficiency of a “

copy-on-write”

operation, the method comprising;

receiving new data to be written to a solid state drive (SSD);

receiving 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;

receiving 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;

writing the new data to a new physical location on the SSD different from the first physical location;

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

mapping the second logical address to the first physical location.

2. The method of claim 1, wherein mapping the second logical address to the first physical location comprises modifying a mapping table such that the second logical address maps to the first physical location.

3. The method of claim 1, wherein the new data, first logical address, and second logical address are received as arguments of a command.

4. The method of claim 1, wherein writing the new data to a new physical location further comprises obtaining the new physical location from a free block list.

5. The method of claim 1, further comprising copying the original data from the first physical location to a third physical location on a different SSD.

6. The method 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 layer.

7. The method of claim 1, wherein the first and second logical addresses are logical block addresses.

8. The method of claim 1, wherein writing the new data to a new physical location comprises using a wear-leveling algorithm to select the new physical location.

9. A method for increasing the efficiency of a “

copy-on-write”

operation, the method comprising;

receiving, by a storage virtualization layer, a write command;

determining, by the storage virtualization layer, whether a copy-on-write operation is required in response to the write command; and

sending, by the storage virtualization layer in the event the copy-on-write operation is required, a command to a solid state drive (SSD) to perform an enhanced copy-on-write operation thereon, the command having as arguments;

(1) new data to be written to the SSD;

(2) a first logical address specifying a logical location where the new data should be written to the SSD; and

(3) a second logical address specifying a logical location where the original data should be available on the SSD.

10. The method of claim 9, wherein the first and second logical addresses are logical block addresses.

11. The method of claim 9, wherein the enhanced copy-on-write operation causes only a single write to be performed on the SSD.

12. The method of claim 9, further comprising determining, by the storage virtualization layer, whether the original data needs to be copied to a second SSD.

13. The method of claim 12, further comprising returning, by the storage virtualization layer, a write acknowledgement prior to copying the original data to the second SSD.