Re: Possible causes for database corruption and solutions

* Craig Ringer:

> On 16/12/2009 3:54 PM, Florian Weimer wrote:
>> * Michael Clark:
>>
>>> The solution to the problem seemed to be to change the value for the
>>> wal_sync_method setting to fsync_writethrough from the default of fsync.
>>> I was curious if there were perhaps any other reasons that we should look
>>> at?  Or if there may be other alternatives to changing the wal_sync_method
>>> setting.
>>
>> Fsync and related settings only matter if the operating system (not
>> just the database) crashes.  Does this happen frequently for you?
>
> When you're dealing with end users who have machines running
> god-knows-what kinds of awful hardware drivers

Even Mac OS X?  There should be less variety.

> and with no power protection, then I expect it does. Add laptop
> users with ageing/flakey batteries, laptops let go flat after they
> go into powersave suspend, etc, and you're sure to see plenty of
> cases of apparent crashes.

I hope that Mac OS X turns off write caches on low battery.

Improperly disconnected external drives are quite common and the
effect mimics operating system crashes, but is it common to store
PostgreSQL databases there?  I don't think so.

--
Florian Weimer                <fweimer@bfk.de>
BFK edv-consulting GmbH       http://www.bfk.de/
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