On 2017-02-09 22:58, Andrei Borzenkov wrote:
07.02.2017 23:47, Austin S. Hemmelgarn пишет:
...
Sadly, freezefs (the generic interface based off of xfs_freeze) only
works for block device snapshots. Filesystem level snapshots need the
application software to sync all it's data and then stop writing until
the snapshot is complete.
I expect databases to be using directio, otherwise we have problems even
without using snapshots. Is it still an issue with directio?
It is less of an issue, but it's still an issue because you can still
call for snapshot creation in the middle of an application I/O request.
In other words, the application wouldn't need to worry about syncing
data, but it would need to worry about making sure it's not actually
writing anything when the snapshot happens.
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