- ONTAP 9
- The snapshot is safely written to disk on the first consistency point after a snapshot command is issued.
- The size etc are computed after the face by a slow
ownblocks_calcscan that is deliberately throttled.
- We run the
ownblocks_calcwhen a snap is created, or blocks used completes (kicked off after a snap delete) or if a list command is executed.
- Further, since we only invalidate the values when
blks usedruns, it is possible that the values become quite stale until
blks usedcan get restarted every time a new delete occurs so it might take a long time for the
ownblocksto get a chance to run & update the values, but there is no data integrity issue as far as the snapshot itself is concerned.
wafl scan ownblocks_calcfrom nodeshell forces us to recalculate own blocks values through the scanner even if they are valid/scan has not been kicked off through blocks used which is why you see updated values once this is executed.
::> set advanced ::*> run local wafl scan status volume_name Volume volume_name: Scan id Type of scan progress 843657 block ownership calculation block 19994 of 30803