Re: Decreasing the data loss after failover

On Fri, Jun 5, 2015 at 8:47 PM, sinasaharkhiz <sinas1991(at)gmail(dot)com> wrote:

> Thanks for your answer.
> This will not work for my situation. Because the hard disk of my server is
> failed and the only data I got are the wal files transferred to my backup
> server and I can only perform my recovery process with base backup and wal
> files stored by barman.
> PS: I'm trying to use a specific archive_timeout (less than 15 minutes) to
> see how that will affect the backup size.
>
> Sina
>
>
>
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I'm not sure how you set Barman up, but it should have been backing up your
WAL files as well as performing base backups of your data. Part of the
Barman setup is configuring your archive_command. Wherever this points to
is where your missing WAL files should have gone. If you don't have those
WAL files, or know where Barman was saving them, then you may be out of
luck on that missing data. If the built in restore commands did not bring
things back up to the way you expected them, I'd take a closer look and
make sure Barman was actually doing proper backups.

What version of PostgreSQL are you running? If you're on 9.0+, you should
be using streaming replication instead of WAL shipping. Otherwise your
slave will only ever be as caught up as fast as you can ship WAL files
over. This was a severe limitation in older versions of Postgres that has
been overcome for nearly 5 years now.

Also, if you're not running 9.0+, you're out of support and no longer
receiving security and bug fix updates, which should be of great concern if
you're handling financial data.

I would also encourage you to read up on how to manually perform backup &
recovery with the tools that PostgreSQL comes with. Be sure you understand
everything in this section of the PostgreSQL documentation (note this is
for 9.4): http://www.postgresql.org/docs/9.4/interactive/backup.html. Pay
particular attention to basebackups & wal archiving. Barman is a nice tool,
but it really hides a lot of important steps that you need to know to
understand how to perform recovery in a disaster situation. If you don't
understand what it's doing under the hood, you'll very likely be in this
predicament again because if its built in recovery script doesn't work,
then you're left not knowing what to do.

--
Keith Fiske
Database Administrator
OmniTI Computer Consulting, Inc.
http://www.keithf4.com