Re: BUG #7883: "PANIC: WAL contains references to invalid pages" on replica recovery

On Thu, Feb 21, 2013 at 4:04 AM, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com
> wrote:

> I'd like to see the contents of the WAL, starting from the last
> checkpoint, up to the point where failover happened. In particular, any
> actions on the relation base/16385/16430, which caused the error.
> pg_controldata output on the base backup would also interesting, as well as
> the contents of backup_label file.
>
> How long did the standby run between the base backup and the failover? How
> many WAL segments?
>
> One more thing you could try to narrow down the error: restore from the
> base backup, and let it run up to the point of failover, but shut it down
> just before the failover with "pg_ctl stop -m fast". That should create a
> restartpoint, at the latest checkpoint record. Then restart, and perform
> failover. If it still throws the same error, we know that the WAL record
> that touched the page that doesn't exist was after the last checkpoint.
>

Unfortunately, it looks like we lost the bad wal segments and necessary
base backup due to our archiving mechanism. We don't yet have a principled
way of saving systems for forensics. I thought I had manually accounted for
everything to keep this "on ice" but I missed a step and the system was
archived. I apologize. I'll see if I can add something for us to better
support this.

For what it's worth the failover was done at 2013-02-14 23:55:44 +0000 and
the base backup used was dated 2013-02-15 00:49:22 +0000.

I'll follow up in case we run into this again.