Re: Raid Controller Write Cache setting for WAL and Data

On Wed, Feb 16, 2011 at 04:40:43PM +0100, Piotr Gasidło wrote:

> Is it safe, to have RAID controller (not BBC) write cache _enabled_
> for disks where data are stored and write cache _disabled_ for disks
> where WAL segments are stored?

No.

> I _can_ afford of loosing some data in case of power failure. But I'm
> afraid of having database in unrecoverable state after crash.

It could be.  Suppose you had the crash at the exact moment when the
the WAL was getting flushed.  Now you'll have a corrupt table.  It
will likely start up, but some time later when someone goes to get
that data, you'll run into a problem.

A battery is one of the simplest and cheapest things you can do to
make your database system more reliable and faster at the same time.

A


--
Andrew Sullivan
ajs@crankycanuck.ca