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 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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