Just a little followup on this problem.
We've moved the database to another server where it ran without problems.
HP just released new raid controller drivers for Suse and a firmware
update for the controller itself.
Until now the problem hasn't occurred anymore.
Thanks!
Jo.
Chris Travers wrote:
> Jo De Haes wrote:
>
>> OK. The saga continues, everything is a little bit more clear, but at
>> the same time a lot more confusing.
>>
>> Today i wanted to reproduce the problem again. And guess what? A
>> vacuum of the database went thru without any problems.
>>
>> I dump the block i was having problems with yesterday. It doesn't
>> report an invalid header anymore and it contains other data!!!
>>
> Inconsistant problems esp. with PostgreSQL are usually the result of
> hardware failure.
>
>> Turns out the data that was returned yesterday belongs to another
>> database!
>>
>> Some more detail about the setup. This server runs 2 instances of
>> postgresql. One production instance which is version 8.0.3. And
>> another testing instance installed in a different folder which runs
>> version 8.1.3 Am I wrong thinking this setup ought to work?
>
>
> No. Ihave done it before too. PostgreSQL instances running on
> different ports or addresses are sufficiently isolated to prevent this
> from being a problem.
>
>>
>> Both instances use completely seperated data folders.
>>
>> So the first dump returned data that actually belongs to an 8.0.3
>> database (that runs fine). And today without _any_ intervention that
>> same block returns the correct data and the complete database is fine.
>>
>> Where is the problem?
>> The fact that i'm running 2 different instances?
>> Cache on raid controller messing up?
>> Some strange voodoo?
>
>
> I would see what sort of memory testing suite you can run on your system
> first (memtestx86, for example) and go from there. It sounds to me like
> some sort of a hardware issue. It *could* be bits flipped anywhere,
> from the writehead on the disk to the main system memory or the CPU.
>
> The likelihood that it is a random RAM error is reduced if you are using
> ECC RAM. Otherwise it could be anything.
>
> This being said, when I have seen bits flipped by the CPU usually you
> get a lot of index issues and shared memory corruptions, so I would be
> more inclined to think that this was RAM or RAID cache.
>
> Best Wishes,
> Chris Travers
> Metatron Technology Consulting
>
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