On 1/18/23 10:54, Rob Sargent wrote:
On 1/18/23 09:38, HECTOR INGERTO wrote:
I wanted to understand the underlying issue.
I use ZFS snapshots instead of a “correct” backup because with only two
machines it allows me to have backups in the main machine and in the
secondary too that acts as ho
On 1/18/23 09:38, HECTOR INGERTO wrote:
I wanted to understand the underlying issue.
I use ZFS snapshots instead of a “correct” backup because with only
two machines it allows me to have backups in the main machine and in
the secondary too that acts as hotspare at the same time.
To accompli
<mailto:pgsql-gene...@postgresql.org>
Asunto: Re: Are ZFS snapshots unsafe when PGSQL is spreading through multiple
zpools?
On Tue, 2023-01-17 at 15:22 +, HECTOR INGERTO wrote:
> > Another case: a transaction COMMITs, and a slightly later transaction reads
> > the data
> >
On Tue, 2023-01-17 at 15:22 +, HECTOR INGERTO wrote:
> > Another case: a transaction COMMITs, and a slightly later transaction reads
> > the data
> > and sets a hint bit. If the snapshot of the file system with the data
> > directory in it
> > is slightly later than the snapshot of the file
On Tue, Jan 17, 2023 at 03:22:02PM +, HECTOR INGERTO wrote:
> > Another case: a transaction COMMITs, and a slightly later transaction reads
> the data
> > and sets a hint bit. If the snapshot of the file system with the data
> directory in it
> > is slightly later than the snapshot of the file
> Another case: a transaction COMMITs, and a slightly later transaction reads
> the data
> and sets a hint bit. If the snapshot of the file system with the data
> directory in it
> is slightly later than the snapshot of the file system with "pg_wal", the
> COMMIT might
> not be part of the snap
On Mon, 2023-01-16 at 14:37 +, HECTOR INGERTO wrote:
> > 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 writ
On Mon, Jan 16, 2023 at 3:37 PM HECTOR INGERTO
wrote:
> > 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 WA
> On 16 Jan 2023, at 15:37, HECTOR INGERTO wrote:
>
> > 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 write
> 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 tha
On Mon, 2023-01-16 at 08:41 +, HECTOR INGERTO wrote:
> I have understood I shall not do it, but could the technical details be
> discussed about
> why silent DB corruption can occur with non-atomical snapshots?
The database relies on the data being consistent when it performs crash
recovery.
I have understood I shall not do it, but could the technical details be
discussed about why silent DB corruption can occur with non-atomical snapshots?
er.net>
*Enviado: *domingo, 15 de enero de 2023 20:36
*Para: *HECTOR INGERTO <mailto:hector_...@hotmail.com>
*CC: *pgsql-gene...@postgresql.org
*Asunto: *Re: Are ZFS snapshots unsafe when PGSQL is spreading through
multiple zpools?
On Sun, Jan 15, 2023 at 8:18 PM HECTOR INGERTO wrote:
ZFS snapshots unsafe when PGSQL is spreading through multiple
zpools?
On Sun, Jan 15, 2023 at 8:18 PM HECTOR INGERTO
mailto:hector_...@hotmail.com>> wrote:
Hello everybody,
I’m using PostgreSQL on openZFS. I use ZFS snapshots as a backup + hotspare
method.
>From man zfs-snapshot: “
On Sun, Jan 15, 2023 at 10:57 PM HECTOR INGERTO
wrote:
>
>
> > But you cannot and should not rely on snapshots alone
>
>
>
> That’s only for non atomic (multiple pools) snapshots. Isn’t?
>
Right. For single-filesystem installs it should be fine. Just make sure it
has both the data and the WAL di
On Sun, Jan 15, 2023 at 8:18 PM HECTOR INGERTO
wrote:
> Hello everybody,
>
>
>
> I’m using PostgreSQL on openZFS. I use ZFS snapshots as a backup +
> hotspare method.
>
>
>
> From man zfs-snapshot: “Snapshots are taken atomically, so that all
> snapshots correspond to the same moment in time.” So
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