Re: File system snapshots for multiple file systems

I have applied the following patch to document the use of continuous
archiving backups to allow non-simultaneous snapshots.

I don't think we want to go any farther to stop WAL recycling during
back backups.

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Bruce Momjian wrote:
> Right now it isn't possible to use file system snapshots a reliable
> backup if you are using multiple file systems for tablespaces because
> most systems don't allow the simultaneous snapshoting of multiple file
> system. Our documentation mentions this:
>
> If your database is spread across multiple file systems, there might not
> be any way to obtain exactly-simultaneous frozen snapshots of all the
> volumes. For example, if your data files and WAL log are on different
> disks, or if tablespaces are on different file systems, it might not be
> possible to use snapshot backup because the snapshots must be
> simultaneous. Read your file system documentation very carefully before
> trusting to the consistent-snapshot technique in such situations. The
> safest approach is to shut down the database server for long enough to
> establish all the frozen snapshots.
>
> However, it occurred to me that if someone turned on continuous arciving
> during the file system snapshots, then you could use PITR to recover
> from file system snapshots that were not simultaneous.
>
> Should this be documented?
>
> --
> Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
> EnterpriseDB http://enterprisedb.com
>
> + If your life is a hard drive, Christ can be your backup. +
>
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--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +