Re: root cause of corruption in hot standby

[Mike Broers <mbroers@xxxxxxxxx>]

A fresh replica using pg_basebackup on the same system generated similar errors:.

cp: cannot stat ‘/mnt/backup/pgsql/9.5/archive/00000002.history’: No such file or directory

2018-09-19 08:36:23 CDT [57006]: [179-1] user=,db= LOG:  restored log file "0000000100007CFC00000040" from archive

2018-09-19 08:36:23 CDT [57006]: [180-1] user=,db= LOG:  incorrect resource manager data checksum in record at 7CFC/405ED198

I am going to run file system checks now.. Maybe the backup volume the archived wals get rsync'ed to has problems and is corrupting on the replay?  No checksum alerts on primary or an additional replica..

If I can supply additional info that would help get some advice please let me know.  

Postgres 9.5.14, CentOS 7, ext4 filesystem, hyper-v VM

On Mon, Sep 10, 2018 at 8:40 AM Mike Broers <mbroers@xxxxxxxxx> wrote:

Well I've verified my primary backups are working, and think my plan is to patch to 9.5.14, reprime a replica in the same environment and see how it goes unless someone has an idea of something to check on the host to avoid future corruption...

On Thu, Sep 6, 2018 at 12:28 PM Mike Broers <mbroers@xxxxxxxxx> wrote:

So I have discovered corruption in a postgres 9.5.12 read replica, yay checksums!

2018-09-06 12:00:53 CDT [1563]: [4-1] user=postgres,db=production WARNING:  page verification failed, calculated checksum 3482 but expected 32232

2018-09-06 12:00:53 CDT [1563]: [5-1] user=postgres,db=production ERROR:  invalid page in block 15962 of relation base/16384/464832386

The rest of the log is clean and just has usual monitoring queries as this isnt a heavily used db.

This corruption isnt occurring on the primary or a second replica, so I'm not freaking out exactly, but Im not sure how I can further diagnose what the root cause of the corruption might be. 

There were no power outages.  This is a streaming hot standby replica that looks like it was connected fine to its primary xlog at the time, and not falling back on rsync'ed WALS or anything.  We run off an SSD SAN that is allocated using LVM and I've noticed documentation that states that can be problematic, but I'm unclear on how to diagnose what might have been the root cause and now I'm somewhat uncomfortable with this environments reliability in general.  

Does anyone have advice for what to check further to determine a possible root cause?  This is a CentOS 7 vm running on Hyper-V.  

Thanks for any assistance, greatly appreciated!

Mike