Persistent storage device management
A method includes receiving a request to write data at a virtual location, writing the data to a physical location on a persistent storage device, and recording a mapping from the virtual location to the physical location. The physical location corresponds to a next free block in a sequence of blocks on the persistent storage device.
1. A method comprising:
receiving from a user a first request to write first data at a first virtual location;
writing the first data to a first physical location on a persistent storage system;
recording a first mapping from the first virtual location to the first physical location;
receiving from the user a second request to write second data at the first virtual location;
writing the second data to a second physical location on the persistent storage system, the second physical location corresponding to a next free block in a sequence of blocks on the persistent storage system, and being different from the first physical location, wherein each block on the persistent storage system is written to once, before any block of the persistent storage system is written to a second time;
replacing the first mapping with a second mapping from the first virtual location to the second physical location; and
marking the first physical location as dirty.
2. The method of claim 1 , wherein the first virtual location and the first physical location are not correlated with one another.
3. The method of claim 1 , wherein the first physical location is determined by a head counter.
4. The method of claim 3 , further comprising after writing the data to the first physical location, updating the head counter.
5. The method of claim 1 , wherein writing the second data to the second physical location occurs without performing a read from the first physical location.
6. The method of claim 1 , further comprising:
calculating a checksum for the first data; and
recording the checksum in metadata associated with the persistent storage system.
7. The method of claim 1 , further comprising determining that a garbage collection condition is met.
8. The method of claim 7 , wherein the garbage collection condition comprises one or more of:
a number of gaps on the persistent storage system exceeding a first threshold;
an activity level of the persistent storage system falling below a second threshold;
a free capacity of the persistent storage system falling below a third threshold; or
an expiration of a time period.
9. A system comprising:
one or more processors; and
a memory;
wherein the memory comprises instructions which, when executed by the one or more processors, configure the one or more processors to perform the method of claim 1 .
10. One or more non-transitory computer readable media comprising instructions which, when executed by one or more processors, cause the one or more processors to perform the method of claim 1 .
11. The method of claim 1 , wherein the first mapping is overwritten by the second mapping.
12. The method of claim 1 , wherein the persistent storage system comprises a persistent storage device.
13. The method of claim 1 , wherein the persistent storage system comprises an array of persistent storage devices.