Re: Help desperately needed: reoccurring invalid page

Hi,

Ian Westmacott wrote:

>Mauri, I'm no expert but I can tell you what I know. We
>have experienced this same problem, and I asked a
>similar question not too long ago.
>
>- This is probably due to some sort of I/O problem. In
> our case, it occurs very frequently on reboots, and
> it appears to be related to dirty buffers not being
> flushed out when the partition is unmounted. Look
> into a newer kernel, and/or newer/different
> filesystem (we have seen this in various flavors
> of the 2.4.6 kernel with XFS, JFS and EXT3).
>
>
Uh. As our cheap server is a virtual machine under a virtuozzo
(http://www.sw-soft.com/products/virtuozzo/) I have no control over what
kernel to run or what filesystem to use. Nor has there been frequent
reboots. I have restarted the virtual server twice in 4 months and the
provider has done it once since production started. But as it might
still be a filesystem problem (vzfs) I should try to find documentation
on vzfs to see if I can do something to increase its "reliability" or if
the provider can do that.

The client side did fail very frequently for a while due non mature
w-lan card driver and that might have caused the corruption that did not
got fixed properly by my inept attempts and still lurks around.

>- If you have invalid page headers, you should take a
> look at the run-time parameter zero_damaged_pages.
> You can use this to fix up a table (losing the data
> on the bad pages).
>
>
>
Thanks I will try that.

>- We have not found a way around the missing log file
> problem. This appears to end up locking some rows
> forever.
>
>
It seems to me that the best course for action for us would be: Zeroing
damaged pages. Dump every database excluding templates.
Shutdown. Remove provider's postgresql-rpms and install the latest rpms
on 7-series of Postgresql from Fedora legacy/pgfoundry. Restore
databases. Manually merge changes from older backups that got zeroed.
Upgrade client-side to the same version of postgresql as the server
side. Recompile libraries and applications. Startup. Backup. Increase
frequenzy of backups and hope for the best.