Re: Bad iostat numbers

The problem I see with software raid is the issue of a battery backed unit:
If the computer loses power, then the 'cache' which is held in system
memory, goes away, and fubars your RAID.

Alex

On 12/5/06, Michael Stone <mstone+postgres(at)mathom(dot)us> wrote:
>
> On Tue, Dec 05, 2006 at 01:21:38AM -0500, Alex Turner wrote:
> >My other and most important point is that I can't find any solid
> >recommendations for a SCSI card that can perform optimally in Linux or
> >*BSD. Off by a factor of 3x is pretty sad IMHO. (and yes, we know the
> >Adaptec cards suck worse, that doesn't bring us to a _good_ card).
>
> This gets back to my point about terminology. As a SCSI HBA the Adaptec
> is decent: I can sustain about 300MB/s off a single channel of the
> 39320A using an external RAID controller. As a RAID controller I can't
> even imagine using the Adaptec; I'm fairly certain they put that
> "functionality" on there just so they could charge more for the card. It
> may be that there's not much market for on-board SCSI RAID controllers;
> between SATA on the low end and SAS & FC on the high end, there isn't a
> whole lotta space left for SCSI. I definitely don't think much
> R&D is going into SCSI controllers any more, compared to other solutions
> like SATA or SAS RAID (the 39320 hasn't change in at least 3 years,
> IIRC). Anyway, since the Adaptec part is a decent SCSI controller and a
> lousy RAID controller, have you tried just using software RAID?
>
> Mike Stone
>
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