Date: Mon, 18 Feb 2019 11:26:38 -0500
From: Stephen Frost <sfrost@snowman.net>
To: jk7255@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #15636: PostgreSQL 11.1 pg_basebackup backup to a CIFS
 destination throws fsync error at end of backup
Message-ID: <20190218162638.GH6197@tamriel.snowman.net>
References: <15636-d380890dafd78fc6@postgresql.org>
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Greetings,

* PG Bug reporting form (noreply@postgresql.org) wrote:
> 				archive_mode = 'on'
> 				archive_command = 'test ! -f /pgxlog1/data1/%f || cp /pgxlog1/data1/%f
> /cifs/backups/<backupDirectoryName>/dmp/archive/%f'

I realize you were complaining about pg_basebackup here, but since you
shared your config, I wanted to point out that the above is an
absolutely *terrible* archive_command, *especially* when you've got a
network filesystem involved.

There's no guarantee with that archive command that the WAL makes it to
the backup server or that it's completely written out on the backup
server before the PG server removes the WAL- if something happened (a
network hiccup, the CIFS server being rebooted, or the PG server
restarting) there's a real possibility that you'd lose some portion of
your WAL, which could make a backup invalid, or could make it so you
can't do PITR.

Please don't roll your own backup solution like this.

Thanks!

Stephen

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