Subject: Re: RAID-5 benchmark results
To: Giles Lean <>
From: Johnny Lam <>
List: netbsd-users
Date: 12/12/2001 08:30:56
On Wed, Dec 12, 2001 at 06:45:44PM +1100, Giles Lean wrote:
> > First off, it was _vital_ that write-back-cache was enabled
> > on the SCSI disks.  Turning it on made a _huge_ difference in the write
> > performance.
> You know this risks data loss if you have a power outage?  Worst case
> is that filesystem meta data updates are re-ordered and/or lost, and
> fsck may not be able to repair the damage.  Not likely, but possible.

Well, who runs production file servers with RAID and doesn't invest in
a UPS?  Not me =)

> You're in good company of course -- most (all?) IDE disks ship with
> write back cache enabled.  PC hardware "engineering" ... sigh. :-(

Not all hardware RAID cards are battery-backed either, so it's not just
PC hardware.  However, I think we're all aware of the shortcomings of
cheap PC hardware.


	-- Johnny Lam <>