RE: Are ZFS snapshots unsafe when PGSQL is spreading through multiple zpools?

[HECTOR INGERTO <hector_25e@xxxxxxxxxxx>]

> The database relies on the data being consistent when it performs crash recovery.
> Imagine that a checkpoint is running while you take your snapshot.  The checkpoint
> syncs a data file with a new row to disk.  Then it writes a WAL record and updates
> the control file.  Now imagine that the table with the new row is on a different
> file system, and your snapshot captures the WAL and the control file, but not
> the new row (it was still sitting in the kernel page cache when the snapshot was taken).
> You end up with a lost row.
>
> That is only one scenario.  Many other ways of corruption can happen.

 

Can we say then that the risk comes only from the possibility of a checkpoint running inside the time gap between the non-simultaneous snapshots?