Re: dpt_i2o and i2o_block on amd64 etch
On Mon, May 14, 2007 at 08:59:17AM -0500, Neil Gunton wrote:
> I've never done that (at install time anyway) - are you talking about
> just using something like modprobe or insmod?
Yes using modprobe (insmod should almost never be used manually).
> I always thought Adaptec was a pretty major company. I guess I was wrong
> (or at least chose a card that turned out to be kind of a loser). I
> thought that drivers were difficult back in 2005 because the card was so
> new. Now it appears the opposite - nobody is using it because it just
> never took off at all.
I remember all the hype about i2o a long time ago, and I thought it had
totally disappeared. I was rather surprised a couple of years ago when
someone asked how to get i2o working with the amd64 sarge installer.
Adaptec is a large company, but it seems a lot less low end users bother
with scsi anymore. I think the main market is enterprise level with
SAS today. Parallel shared single point of failure busses are fortunately
going away now.
> Maybe next time I should go with one of those 3Ware SATA RAID cards. I
> heard they are blowing the doors off anything else in terms of speed.
> But I'm a little concerned about SATA drive reliability.
Well my personal experience is that I have had less drive failures with
SATA than with SCSI. So who knows. People with larger data sets or
different brands will have different results.
> Does anyone have a handle on if/why SCSI would be more reliable than
> SATA? I remember reading that SCSI drives are built better, but SATA
> seems so attractive pricewise these days that I'm wondering if I should
> just go with that next time. How about speed with SATA vs SCSI - anybody
> have practical experience of that?
Well certainly the claim is that scsi drives are better built, although
I think today the main feature of scsi drives is that you can get 15k
rpm drives with faster seek times (well not counting the WD raptor
drives which seem to be basically scsi style disks with SATA interface,
at scsi prices). I think the main reason sata/pata drives are cheaper
is simply volume for the most part.
> If you still want tops in speed and reliability, is SCSI still the way
> to go? It seems to be dying, except perhaps on the server.
If you want fast random access, you go scsi. If you want pure
sequential transfer rate, you go sata. The much higher density of the
media on the large sata drives can not be matched by the higher rpm but
much lower density of even the largest scsi drives. The fast rpm and
low seek time is for random access and multiple simultanious accesses,
but not for transfer rate. You generally can make up the transfer rate
using striping or raid5/6 or similar. The idea seems to be that having
smaller disks with faster access to any given sector using many disks
and hence many heads, is faster than using a few large disks with less
headers as a result. After all SAS drives seem to be going 2.5" to a
large extent in order to fit even more disks with more heads in the same
space.
--
Len Sorensen
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