Hey all
I know this list isn't the place, but my problem is unique, and it
requires a good concentration of experience and knowhow, and this list has
that. So I'll sent it here, and mayhaps someone can help me.
Here's the prob:
I managed to swap some HW for an IBM ServeRAID-4Lx SCSI/RAID controller
and two Cheetah 10K drives. The controller is a 64-bit PCI card. According
to SPEC, it will also work at 33MHz/32bit PCI, albeit under the PCI
bottleneck of 133MB/sec.
I gingerly stuck the lot in my PC (in a 32-bit 33MHz PCI slot), revved it
up, updated firmware (to 6.0.31), Configured a 2-disk stripe
(each such disk does 55MByte/sec according to
<flame-resistant-suit> (Apologies for having benchmarked under windows,
I'm spoiled and like sexy graphs) HD-Tach and Sandra </flame-resistant-suit> (when on
a simple Adaptec Ultra2 [80M/S] controller.
Two such disks should stripe well on my 133MB/sec PCI bus).. I ran HD-TACH and got...
20MB/sec. That's almost the
100 I was expecting, but.. not quite.
I tried the following with zilch results:
1. Forcing all SCSI modes from Ultra-160(160M/S) to Ultra (40M/S) - this
is done using their support CD.
2. Configuring the biggest RAID cluster size (64K)
3. Changing flat cables (terminated of course) - all my cables work just
fine on an Adaptec Ultra2 controller. Each single drive does 55M/S.
4. Using only one harddrive in a "one-drive-raid-array"... still 20M/S.
5. Changing PCI slots
6. Replacing the RAID controller under warranty.
7. Sticking the whole controller+disk setup in several other computers, an
older Duron and an Newer P4, all with 32bit/33MHz PCI buses.
Through all of this rigorous experimenting, the controller continued to
bottleneck at 20MB/Sec.
I feel like something the size of an elephant is sitting right under my
nose and I can't see it. And it's annoying the hell out of me.
Anyone got any useful ideas? (Other than to try sticking it into a 64-bit
PCI slot, which I currently don't have access to)
Thanks!
--
Miki Shapiro <aris at pharoe dot com>
Unixophilic Software Developer
---------------------------------------------
Tel: +972-(56)-322433 ICQ: 3EE853
---------------------------------------------
"There are two major products that come from Berkeley:
LSD and UNIX. We don't believe this to be a coincidence."
-- Jeremy S. Anderson
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