Re: SATA Raid Controller

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Wed, Jun 04, 2008 at 01:49:12PM +0300, Jukka Marin wrote:
> On Wed, Jun 04, 2008 at 12:20:52PM +0200, Manuel Bouyer wrote:
> > > I had a 3ware for a while, but was disappointed in the RAID5 performance.
> > > I talked to the 3ware tech support and while they were trying to help,
> > > the problem was never solved.
> > 
> > For read or write ? writes without the battery-backed cache are slow,
> > but that expected.
> 
> I had the battery backup, but still writes were "slow", especially extracting
> pkgsrc.tar.gz (according to systat, the effective speed dropped to well below
> 1 MB/s).

I never noticed this. Are you sure the write-back cache was active ?
The controller will disable it under certains conditions. It does it
when one drive failed or is reconstructing, and I guess it's doing it too
just after a volume configuration, while it's rebuilding the parity.
I can say when a drive has failed because writes becomes very, very slow :)


> With Areca, I'm getting better write speed under Xen/domU than with
> 3ware without Xen.
> 
> > But I suspect all this is hightly hardware-dependant, especially
> > chipset-dependant. Tests not run on the same motherboard with the
> > same settings don't mean much ...
> 
> I was using the same motherboard with 3ware and Areca.

My point is that using a different mother board could give different
resulsts for both adapters.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--