On Sep 16, 2009, at 7:11 AM, Tom Carlson wrote:
Hi, I've had a slightly bad experience with port multipliers. I have a PCI-e x1 JMB362 on the host end and a SiI 3726 connected to it. (I think. It's a 1-5 PM). I have 5 disks connected in raid5 and get some fairly appalling write speeds, well below what I'd expect even for raid5 writes. Reads too are fairly slow... $ dd if=/dev/zero of=./blah bs=1M count=512 512+0 records in 512+0 records out 536870912 bytes (537 MB) copied, 47.4814 s, 11.3 MB/s $ dd if=./bigfile.iso of=/dev/null 8474857+0 records in 8474857+0 records out 4339126272 bytes (4.3 GB) copied, 144.667 s, 30.0 MB/s Obviously this isn't the most scientific of tests... :-) but it does show slowness with this particular combination.I'm tempted to go buy a SiI 3132 based controller and compare the results.
I would, those numbers look *really* bad compared to what they could be. -- Doug Ledford <dledford@xxxxxxxxxx> GPG KeyID: CFBFF194 http://people.redhat.com/dledford InfiniBand Specific RPMS http://people.redhat.com/dledford/Infiniband
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