Re: Lying drives [Was: Re: Which OS provides the

Greg Smith wrote:
> On Mon, 13 Nov 2006, Guy Thornley wrote:
>
> > I've yet to find a drive that lies about write completion. The problem
> > is that the drives boot-up default is write-caching enabled (or perhaps
> > the system BIOS sets it that way). If you turn an IDE disks write cache
> > off explicity, using hdparm or similar, they behave.
>
> I found a rather ominous warning from SGI on this subject at
> http://oss.sgi.com/projects/xfs/faq.html#wcache_query
>
> "[Disabling the write cache] is kept persistent for a SCSI disk. However,
> for a SATA/PATA disk this needs to be done after every reset as it will
> reset back to the default of the write cache enabled. And a reset can
> happen after reboot or on error recovery of the drive. This makes it
> rather difficult to guarantee that the write cache is maintained as
> disabled."
>
> As I've been learning more about this subject recently, I've become
> increasingly queasy about using IDE drives for databases unless they're
> hooked up to a high-end (S|P)ATA controller. As far as I know the BIOS

Yes, avoiding IDE for serious database servers is a conclusion I made
long ago.

--
Bruce Momjian bruce(at)momjian(dot)us
EnterpriseDB http://www.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +