Method and system for data integrity
A method is used in ensuring data integrity in data storage. A set of physical pages that include data for a virtual page is identified on a storage device. A set of reconstructed pages is generated from other storage devices, and each reconstructed page corresponds to a page in the set of physical pages. One or more pages from the set of physical pages and the set of reconstructed pages with data yielding a checksum that matches a checksum for the virtual page is identified, and data corresponding to the virtual page from the identified one or more pages is obtained.
1. A method for ensuring data integrity in a storage system, the method comprising:
identifying, on a storage device in a RAID group, a set of physical pages that include data for a virtual page, the virtual page spanning the set of physical pages;
using remaining storage devices in the RAID group to generate a set of reconstructed pages, each reconstructed page corresponding to a page in the set of physical pages;
identifying a combination of pages from the set of physical pages and the set of reconstructed pages that includes data which yields a checksum that matches a checksum for the virtual page; and
obtaining data corresponding to the virtual page from the identified combination of pages.
2. The method of claim 1 , wherein the set of physical pages includes a single physical page.
3. The method of claim 1 , wherein the set of physical pages includes a first physical page and a second physical page, and the set of reconstructed pages includes a reconstructed first physical page and a reconstructed second physical page.
4. The method of claim 3 , wherein the identified combination of pages includes:
the first physical page and the second physical page;
the reconstructed first physical page and the reconstructed second physical page;
the first physical page and the reconstructed second physical page; or
the reconstructed first physical page and the second physical page.
5. The method of claim 1 , wherein identifying the combination of pages comprises:
iterating through different combinations of pages from the set of physical pages and the set of reconstructed pages until the checksum based on data in a particular combination of pages matches the checksum for the virtual page.
6. The method of claim 5 , wherein iterating through the different combinations of pages comprises:
identifying, in a particular combination of pages, data in each page that is included in the virtual page;
calculating a checksum based on the identified data; and
comparing the calculated checksum against the checksum for the virtual page.
7. The method of claim 6 , wherein identifying, in a particular combination of pages, the data in each page that is included in the virtual page comprises:
identifying at least a subset of the data in each page that is included in the virtual page.
8. The method of claim 1 , wherein generating the set of reconstructed pages comprises:
applying a redundancy algorithm to data read from the other storage devices.
9. The method of claim 1 , further comprising:
adding portions on the storage device or other storage devices to garbage collection.
10. A system for use in ensuring data integrity in data storage, the system comprising a processor configured to:
identify, on a storage device in a RAID group, a set of physical pages that include data for a virtual page, the virtual page spanning the set of physical pages;
use remaining storage devices in the RAID group to generate a set of reconstructed pages, each reconstructed page corresponding to a page in the set of physical pages;
identify a combination of pages from the set of physical pages and the set of reconstructed pages that includes data which yields a checksum that matches a checksum for the virtual page; and
obtain data corresponding to the virtual page from the identified combination of pages.
11. The system of claim 10 , wherein the set of physical pages includes a single physical page.
12. The system of claim 10 , wherein the set of physical pages includes a first physical page and a second physical page, and the set of reconstructed pages includes a reconstructed first physical page and a reconstructed second physical page.
13. The system of claim 12 , wherein the identified combination of pages includes:
the first physical page and the second physical page;
the reconstructed first physical page and the reconstructed second physical page;
the first physical page and the reconstructed second physical page; or
the reconstructed first physical page and the second physical page.
14. The system of claim 10 , wherein the processor is further configured to:
iterate through different combinations of pages from the set of physical pages and the set of reconstructed pages until the checksum based on data in a particular combination of pages matches the checksum for the virtual page.
15. The system of claim 14 , wherein the processor is further configured to:
identify, in a particular combination of pages, data in each page that is included in the virtual page;
calculate a checksum based on the identified data; and
compare the calculated checksum against the checksum for the virtual page.
16. The system of claim 15 , wherein the processor is further configured to:
identify at least a subset of the data in each page that is included in the virtual page.
17. The system of claim 10 , wherein the storage device with the set of physical pages and the other storage devices used to generate the set of reconstructed pages are in a RAID group.
18. The system of claim 10 , wherein the processor is further configured to:
apply a redundancy algorithm to data read from the other storage devices.
19. The system of claim 10 , wherein the processor is further configured to:
add portions on the storage device or other storage devices to garbage collection.