Motherboard query...

[Andrew Klaassen]

On Thu, Feb 28, 2002 at 04:07:25PM -0500,
Robert G. Brown wrote:

> We just got a Promise UltraTrak100 TX8 (IDE-SCSI) RAID chassis
> that advertised decent itself as OS-independent plug and play
> -- attach to SCSI bus and go.  The first unit we were shipped
> didn't work under any OS.  The second we were shipped we got
> the vendor (Megahaus) to verify function before shipping and
> it does "work", but it returns unbelieveably poor performance
> at RAID 5 -- a (very) few MB/sec -- under bonnie.

I think the Promise rep quoted us 12MB/s under RAID 5 for the
UltraTrak100 TX8.  We didn't bite.

> IDE is cheap and easy, but we would like a bit of assurance
> that linux won't have (e.g.  DMA) problems when dealing with
> 6-8 ide controllers on one bus.  Is anyone doing this?

Lots of people.  There's even a mailing list for it:

 linux-ide-arrays-subscribe at lists.math.uh.edu

...though I don't know if the archives are online anywhere yet.

Specific things to know, off the top of my head:

75GB IBM drives from the 75GXP line have given a lot of people a
lot of problems.  (Apparently it's a firmware thing with earlier
drives, or something like that.  At this company, we traded all
of ours in for 80GB Seagates.)

Two Promise Ultra100 cards (not the hardware raid cards; I'm not
really familiar with any of those) seems to be the max in one
system.  We've used onboard controllers and SIIG cards alongside
the Promise cards to get the additional ports we've needed.

Stick with 18" cables.  Longer cables work for some people, but
I've never had success with them.  Short cables make it a little
harder to find a suitable case, but these cases:

http://www.lian-li.com/product.php?action=viewPD&prdid=362

...will keep up to five drives properly cooled, in easy reach of
IDE controllers.  With a little imagination and an extra fan or
two, you could easily get 8 or 12 well-cooled drives in a case. 
(We've currently got 8 drives in one of these cases in
production.  We had to drill extra holes in the center cage to
get proper spacing between the drives, and mount an extra fan in
front.)

In the last few days, people have started talking about problems
with 3ware cards (which still seem to be, despite that, the
best-supported hardware RAID IDE controllers available). 
Unfortunately, I haven't really been following that discussion,
so I can't give any more details.

Andrew Klaassen