Archiving logs with snapshots for data recovery
View Patent ↗A method for archiving a log for a data storage system includes the steps of logging host inputs/outputs to the log, creating a snapshot of the log when it is full, resetting a next write offset to the start of the log after the snapshot is created while continuing the logging to the log, performing copy-on-write of the log to the snapshot, and archiving the snapshot to an archived log.
1. A method for one or more processors in a data storage system to log and archive data, comprising:
logging host inputs/outputs (I/Os) to a single log;
when the log is full, creating a snapshot of the log;
after said creating a snapshot of the log, resetting a next write offset to a start of the log while the host I/Os are being logged to the log;
performing copy-on-write of the log to the snapshot of the log;
archiving the snapshot of the log to an archived log while the host I/Os are being logged to the log;
when the log is again full, creating another snapshot of the log;
performing copy-on-write of the log to said another snapshot of the log; and
archiving said another snapshot of the log to the archived log after said archiving the snapshot of the log.
2. The method of claim 1 , further comprising:
deleting the snapshot of the log after it has been archived.
3. The method of claim 1 , wherein the log is selected from the group consisting of a log file and a log volume.
4. The method of claim 1 , wherein the host I/Os are selected from the group consisting of reads and writes to the data storage system.
5. A data storage system, comprising:
a memory storing:
a single log;
at least one snapshot of the log;
an archived log of the log; and
a processor executing instructions for archiving the log, wherein the instructions comprises:
a plurality of instructions for a logging process, comprising:
logging host inputs/outputs (I/Os) to the data storage system to the log;
each time the log is full:
triggering a creation of a snapshot of the log;
after said triggering, resetting a next write offset to a start of the log while the host I/Os are begin logged to the log;
a plurality of instructions for a snapshot process, comprising:
in response to each said triggering a creation of a snapshot of the log:
creating the snapshot of the log;
performing copy-on-write of the log to the snapshot of the log;
a plurality of instructions for an archiving process, comprising:
in response to each said creating the snapshot of the log:
archiving the snapshot of the log to the archived log after any prior snapshot of the log has been archived to the archived log.
6. The data storage system of claim 5 , wherein the plurality of instructions for the archiving process further comprises:
when the snapshot of the log has been archived, deleting the snapshot of the log.
7. The data storage system of claim 5 , wherein the log is selected from the group consisting of a log file and a log volume.
8. The data storage system of claim 5 , wherein the host I/Os are selected from the group consisting of reads and writes to the data storage system.
9. A non-transitory computer-readable storage medium encoded with one or more executable programs to log and archive data, wherein the one or more programs cause one or more processors to perform the following:
logging host inputs/outputs (I/Os) to a single log;
when the log is full, creating a snapshot of the log;
after said creating a snapshot of the log, resetting a next write offset to a start of the log while the host I/Os are being logged to the log;
performing copy-on-write of the log to the snapshot of the log;
archiving the snapshot of the log to an archived log while the host I/Os are being logged to the log;
when the log is again full, creating another snapshot of the log;
performing copy-on-write of the log to said another snapshot of the log; and
archiving said another snapshot of the log to the archived log after said archiving the snapshot of the log.
10. The non-transitory computer-readable storage medium of claim 9 , wherein the one or more programs further cause the one or more processors to perform the following:
deleting the snapshot of the log after it has been archived.
11. The non-transitory computer-readable storage medium of claim 9 , wherein the log is selected from the group consisting of a log file and a log volume.
12. The non-transitory computer-readable storage medium of claim 9 , wherein the host I/Os are selected from the group consisting of reads and writes to the data storage system.