Yeah, I've read something about limiting the SCSI chain to 4 drives. Alas, not possible in my situation. 272 MB/s read from a RAID10 is possibly the practical upper limit, despite the drives being easily able to exceed that. When I'm back at work on Tuesday I'll do a couple of quick tests of the RAID5 array.<br>
<br><div class="gmail_quote">On Fri, May 20, 2011 at 5:08 PM, Adam Thompson <span dir="ltr"><<a href="mailto:athompso@athompso.net">athompso@athompso.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
In any event, yes, a single U320 bus can only do 320MB in aggregate, and its practical limit is around 80% of that. HP's external enclosures are not exactly notorious for being well-balanced equipment...<br>
Only one model in any given product generation will be a single-bus design, that's the economy model.<br>
On a Sun E450 with Ultra-II (40MB/sec) drives, the system backplane is engineered so that no more than 4 drives are connected to any one channel, for example.<br>
Generally speaking, the 4-disk per channel limit is sound engineering.<br>
There's also a curious effect that I've seen but can't explain where more spindles actually slows down the array drastically... I suspect if you recreate that array as RAID 50, you'd see performance gains.<br>
<font color="#888888">-Adam<br>
</font><div class="im"><br>
<br>
Trevor Cordes <<a href="mailto:trevor@tecnopolis.ca">trevor@tecnopolis.ca</a>> wrote:<br>
<br>
</div><div><div></div><div class="h5">>On 2011-05-20 Kevin McGregor wrote:<br>
>> When the SCSI controller BIOS is initialized, it lists all of the<br>
>> drives on both channels, and most of them (as I recall) are described<br>
>> as being set to 80 MB/s with a note that the OS will probably set<br>
><br>
>Weird, see if the SCSI BIOS setup screens let you manually select the<br>
>SCSI speed. You might have to drill down to the per-drive area. I<br>
>know my U320 card gives me choices.<br>
><br>
>80MB/s per drive isn't shabby, though your drives can probably push<br>
>100-150MB/s.<br>
>_______________________________________________<br>
>Roundtable mailing list<br>
><a href="mailto:Roundtable@muug.mb.ca">Roundtable@muug.mb.ca</a><br>
><a href="http://www.muug.mb.ca/mailman/listinfo/roundtable" target="_blank">http://www.muug.mb.ca/mailman/listinfo/roundtable</a><br>
><br>
<br>
_______________________________________________<br>
Roundtable mailing list<br>
<a href="mailto:Roundtable@muug.mb.ca">Roundtable@muug.mb.ca</a><br>
<a href="http://www.muug.mb.ca/mailman/listinfo/roundtable" target="_blank">http://www.muug.mb.ca/mailman/listinfo/roundtable</a><br>
</div></div></blockquote></div><br>