Re: Upgrading my BSDI box, again

On Wed, Jul 30, 2003 at 12:38:54AM -0400, Bruce Momjian wrote:
> 
> [ CC to Kurt and Steven on bsdi list.]
> 
> Guys, I just replied to this email on the BSDi email list.  The issue is
> that someone found that some(most?) IDE drives have write cache enabled,
> though the drives do not preserve the write cache data on power failure.
> 
> I am surprised we have not heard of this failure before because I know
> most vendors who ship PostgreSQL test our crash recovery thoroughly. 
> Are they testing only using SCSI drives?
> 
> Below you will read that my Seagate SCSI drive has write cache disabled,
> but another guy has a Seagate IDE drive that has it enabled, though it
> loses data on power failure.
> 
> Scarey!
> 
> Does anyone have any more detailed information on this?

Not really, just that I had data corruption on SCSI disks which had write
cache enabled and tagged queueing. Disabling write cache has allowed them
to function flawlessly since. The moral seems to be: write cache gives
pretty performance figures, but you really want it swiched off.

Cheers,

Patrick