Date: Thu, 18 Feb 1999 21:57:21 -0600 From: Jonathan Lemon <jlemon@americantv.com> To: freebsd-scsi@freebsd.org Subject: slow disk performance Message-ID: <19990218215721.55546@right.PCS>
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I have a system with the following:
ahc0: <Adaptec aic7880 Ultra SCSI adapter> rev 0x01 int a irq 11 on pci0.6.0
ahc0: aic7880 Wide Channel A, SCSI Id=7, 16/255 SCBs
da1 at ahc0 bus 0 target 1 lun 0
da1: <Quantum XP32150W L915> Fixed Direct Access SCSI-2 device
da1: 20.0MB/s transfers (10.0MHz, offset 8, 16bit), Tagged Queueing Enabled
da1: 2050MB (4199760 512 byte sectors: 255H 63S/T 261C)
da0 at ahc0 bus 0 target 0 lun 0
da0: <IBM DCAS-34330W S65A> Fixed Direct Access SCSI-2 device
da0: 40.0MB/s transfers (20.0MHz, offset 8, 16bit), Tagged Queueing Enabled
da0: 4134MB (8467200 512 byte sectors: 255H 63S/T 527C)
Basically, an ASUS motherboard with an onboard Adaptec, along with
two 7200 rpm disks. However, I can't seem to get more than 6MB/sec
out of the drives, when doing sequential reads or writes:
dd if=/dev/rda1 of=/dev/null bs=64k &
dd if=/dev/rda0 of=/dev/null bs=64k &
iostat 1
tty fd0 da0 da1 cpu
tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id
0 77 0.00 0 0.00 64.00 115 7.17 64.00 103 6.42 0 0 1 1 98
0 76 0.00 0 0.00 64.00 102 6.37 64.00 100 6.25 0 0 1 1 98
0 76 0.00 0 0.00 64.00 118 7.36 64.00 103 6.44 0 0 5 0 95
Is this the maximum I can expect to get from the drives? I get the same
speeds when doing sequential writes as well; I would think it can do
etter than this. There are no "tagged opening" messages in the logfile,
so this is with 64 tags.
--
Jonathan
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