Metadata journal for a storage system

A non-transitory machine-readable storage medium comprising instructions executable by a processor to:

• receive a read request for journal data, wherein the read request specifies a target location range and a target checkpoint;
• in response to a receipt of the read request, perform a first query to retrieve a first entry of a metadata table comprising a plurality of entries, wherein the first entry is a most recent entry in a first subset of entries, and wherein each of the first subset of entries is older than the target checkpoint and records a write range that overlaps at least some of the target location range;
• determine whether a write range recorded in the first entry covers an entirety of the target location range;
• in response to a determination that the write range recorded in the first entry does not cover the entirety of the target location range, determine a remaining portion of the target location range that excludes the write range recorded in the first entry;
• and
• perform a second query to retrieve a second entry of the metadata table, wherein the second entry is a most recent record in a second subset of entries, and wherein each of the second subset of entries is older that the target checkpoint and records a write range that overlaps at least some of the remaining portion of the target location range.

A method comprising:

• receiving, by a controller, a read request for journal data, wherein the read request specifies a target location range and a target checkpoint;
• in response to a receipt of the read request, executing, by the controller, a first query to retrieve a first entry of a metadata table comprising a plurality of entries, wherein the first entry is a most recent entry in a first subset of entries, and wherein each of the first subset of entries is older than the target checkpoint and records a write range that overlaps at least some of the target location range;
• determining, by the controller, whether a write range recorded in the first entry covers an entirety of the target location range;
• in response to a determination that the write range recorded in the first entry does not cover the entirety of the target location range, determining, by the controller, a remaining portion of the target location range that excludes the write range recorded in the first entry;
• and
• executing, by the controller, a second query to retrieve a second entry of the metadata table, wherein the second entry is a most recent record in a second subset of entries that are older that the target checkpoint and record write ranges that overlap at least some of the remaining portion of the target location range.