Fast garbage collection in zoned namespaces SSDs
A data storage device includes a memory device and a controller coupled to the memory device. The data storage device supports zoned namespace. The controller is configured to maintain a zone timestamp table that includes a corresponding timestamp for each zone and add a timestamp to each garbage collection block of the memory device. The controller is further configured to scan a garbage collection block from a last physical block address (PBA) entry to a first PBA entry, determine a zone timestamp for the scanned PBA entry, and compare the zone timestamp to a timestamp of the garbage collection block. The controller is further configured to create and maintain a zone timestamp table and create and maintain a zone based defragmentation table.
1. A data storage device supporting zoned namespace, comprising:
a memory device; and
a controller coupled to the memory device, wherein the controller is configured to:
scan a garbage collection block from a last physical block address (PBA) entry to a first PBA entry;
determine a zone timestamp for a scanned PBA entry;
compare the zone timestamp to a timestamp of the garbage collection block;
create and maintain a zone timestamp table; and
create and maintain a zone based defragmentation table.
2. The data storage device of claim 1 , wherein the controller is configured to assign a timestamp attribute to a first garbage collection block allocated after the data storage device is initialized for a first time.
3. The data storage device of claim 1 , wherein the controller is configured to assign a timestamp attribute to a first garbage collection block during a first garbage collection operation in a lifetime of the memory device.
4. The data storage device of claim 1 , wherein a zone timestamp is the timestamp of the garbage collection block where a zone's first logical block address (LBA) is written to.
5. The data storage device of claim 4 , wherein the zone timestamp is updated upon each zone reset and rewrite.
6. The data storage device of claim 1 , wherein each new start of a zone is assigned a same timestamp as a source garbage collection block.
7. The data storage device of claim 1 , wherein the zone timestamp table includes entries for each zone, where zones that are initialized have a corresponding timestamp and zones that are not initialized are assigned an invalid timestamp.
8. A data storage device supporting zoned namespace, comprising:
a memory device; and
a controller coupled to the memory device, wherein the controller includes:
a shift module;
a zone timestamp table; and
comparison logic, wherein the shift module is configured to determine a zone of a logical block address (LBA) by shifting the LBA by a predetermined number of bits, wherein the shift determines a number of LBAs per zone, divides the LBA by a number of LBAs per zone, and rounds a resulting value down in order to determine the zone.
9. The data storage device of claim 8 , wherein the controller is configured to perform a backwards scan by performing a translation on a last physical block address (PBA) location then moving backwards one PBA to a second from last PBA and performing a translation on the second from last PBA.
10. The data storage device of claim 8 , wherein a host write can update a zone's timestamp even though garbage collection does not update the zone's timestamp.
11. A data storage device supporting zoned namespace, comprising:
a memory device; and
a controller coupled to the memory device, wherein the controller includes:
a shift module;
a zone timestamp table; and
comparison logic, wherein the controller tracks a zone-in-garbage collection block (GCB) valid (ZiG-Valid) bit for each zone in a zone timestamp table.
12. The data storage device of claim 11 , wherein the controller tracks a timestamp for each zone in the zone timestamp table.
13. The data storage device of claim 11 , wherein the ZiG-Valid bit is initialized for each zone to a value of 1 before a host device issues any write command to any zone.
14. The data storage device of claim 11 , wherein when a zone is reset, the ZiG-Valid bit is reverted to 1.
15. The data storage device of claim 14 , wherein for a Zig-Valid value of 1, the comparison logic determines data validity based on corresponding zone timestamp obtained from the zone timestamp table.
16. A data storage device, comprising:
a memory means; and
a controller coupled to the memory means, wherein the controller is configured to:
initiate a zone timestamp table;
assign a timestamp to a first garbage collection block (GCB);
write host data to the first GCB;
update the zone timestamp table;
allocate a second GCB;
write host data to the second GCB; and
update the zone timestamp table, wherein the controller tracks a zone-in GCB valid (ZiG-Valid) bit for each zone in the zone timestamp table.
17. The data storage device of claim 16 , wherein the controller is further configured to increment a timestamp by 1 and assign the incremented timestamp to the second GCB.
18. The data storage device of claim 16 , wherein the controller is further configured to:
select a source GCB;
determine data validity of the source GCB; and
perform garbage collection on the source GCB.