Re: Postgres 9.01, Amazon EC2/EBS, XFS, JDBC and lost connections

From: Craig Ringer <ringerc(at)ringerc(dot)id(dot)au>
To: John R Pierce <pierce(at)hogranch(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Postgres 9.01, Amazon EC2/EBS, XFS, JDBC and lost connections
Date: 2011-10-11 02:44:00
Message-ID: 4E93AD70.2030907@ringerc.id.au
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On 10/10/11 23:29, John R Pierce wrote:

> While xfs_freeze is in effect, all writes are blocked. This is NOT
> what you want to do here, postgres does NOT expect you to take an
> atomic snapshot of the database files, rather, by bracketing your
> backup with pg_start_backup and pg_stop_backup, it puts things in a
> state where a file by file backup will be fine.
>
While true, taking an atomic snapshot should give them lower recovery
times and - all in all - is probably a good thing.
>
> when postgres's writer processes block, I suspect things go sour fast.
They shouldn't!

If blocking writes causes a server failure that persists once writes
have been unblocked, that's a bug IMO. You might have a bit of a backlog
of writes to clear, but after that all should be well, and if it isn't
then something needs fixing.

--
Craig Ringer

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