Scalable SPOR algorithm for flash memories
Methods of sudden power off recovery may include reading dirty-block meta-pages from memory blocks on a dirty block list, recording mapping in formation in open-block meta-pages, serving host commands by looking up logical block addresses (LBAs) in the dirty-block meta-pages and the open-block meta-pages and when an LBA is not found in the dirty-block meta-pages and the open-block meta-pages, reading new mapping information from a dirty table and saving the new mapping information in host-write meta-pages.
1. A method of sudden power off recovery (SPOR), comprising:
reading dirty-block meta-pages from memory blocks on a dirty block list;
scanning open-blocks and recording mapping information thereof in open-block meta-pages;
serving host commands by looking up logical block addresses (LBAs) in the dirty-block meta-pages and the open-block meta-pages; and
when an LBA is not found in the dirty-block meta-pages or the open-block meta-pages, reading new mapping information from a dirty table and saving the new mapping information in host-write meta-pages, and storing dirty information created by host writes in the host-write meta-pages but not in the dirty table.
2. The method of claim 1 , further comprising:
replaying, in the background, the dirty-table meta-pages, the open-block meta-pages, and the host-write meta-pages in order of old to new such that a valid physical address overwrites an invalid physical address if an LBA occurs multiple times in one meta-page.
3. The method of claim 2 , further comprising serving host commands while performing the replaying step.
4. The method of claim 1 , wherein the looking up is performed from a newest meta-page to an oldest meta-page.
5. A system for performing sudden power off recovery (SPOR), comprising:
a dynamic random access memory (DRAM) including a flash transition layer (FTL) table;
a memory storage suitable for storing dirty-block meta-pages, open-block meta-pages, and host-write meta-pages; and
a controller suitable for:
reading the dirty-block meta-pages from memory blocks on a dirty block list;
scanning open-blocks and recording mapping information thereof in the open-block meta-pages;
serving host commands by looking up logical block addresses (LBAs) in the dirty-block meta-pages and the open-block meta-pages; and
when an LBA is not found in the dirty-block meta-pages or the open-block meta-pages, reading new mapping information from the FTL table and saving the new mapping information in the host-write meta-pages, and storing dirty information created by host writes in the host-write meta-pages but not in the dirty table.
6. The system of claim 5 , wherein the controller is further suitable for preserving space in the DRAM for storing the host-write meta-pages.
7. The system of claim 5 , wherein the controller is further suitable for replaying, in the background, the dirty-table meta-pages, the open-block meta-pages, and the host-write meta-pages in order of old to new such that a valid physical address overwrites an invalid physical address if an LBA occurs multiple times in one meta-page.
8. The system of claim 7 , wherein the controller is further suitable for serving host commands while performing the replaying.
9. The system of claim 5 , wherein the controller is further suitable to perform the looking up from a newest meta-page to an oldest meta-page.
10. A memory device, comprising:
a controller configured to:
read dirty-block meta-pages from memory blocks on a dirty block list;
scanning open-blocks and record mapping information thereof in open-block meta-pages;
serve host commands by looking up logical block addresses (LBAs) in the dirty-block meta-pages and the open-block meta-pages; and
when an LBA is not found in the dirty-block meta-pages or the open-block meta-pages, read new mapping information from a dirty table and save the new mapping information in host-write meta-pages, and store dirty information created by host writes in the host-write meta-pages but not in the dirty table.
11. The memory device of claim 10 , wherein the controller is further configured to replay, in the background, the dirty-table meta-pages, the open-block meta-pages, and the host-write meta-pages in order of old to new such that a valid physical address overwrites an invalid physical address if an LBA occurs multiple times in one meta-page.
12. The memory device of claim 10 , wherein the controller is further configured to serve host commands during replay.
13. The memory device of claim 10 , wherein the looking up is performed from a newest meta-page to an oldest meta-page.