Date: Fri, 12 Mar 1999 09:43:00 +0100 From: sthaug@nethelp.no To: cc@137.org Cc: freebsd-scsi@freebsd.org Subject: Re: SCSI disk oddities and Buslogic problems.. Message-ID: <3236.921228180@verdi.nethelp.no> In-Reply-To: Your message of "Fri, 12 Mar 1999 01:16:30 -0600" References: <19990312071630.5163DB1@friley-185-205.res.iastate.edu>
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> I recently purchased a two new disks, and have noticed some odd behavior.
> The drives are IBM DDRS-34560D's. Anyways, whenever I get new disks, I
> like to benchmark them.
>
> In this case, I have found that while running the following commands that
> the data transfer is very erratic.
>
> dd if=/dev/rda2s3 of=/dev/null bs=128k (or any place on the disk..)
>
> iostat -w 1 da2
>
> Are the statistics output by iostat accurate? The values output by iostat
> usually range from 4 to 9MB/s for the DDRS drives. Although it seems
> random, it it is consistent in the same place on the drives. Does anyone
> else have any input on the DDRS drives? I'm sure it is harmless, but I
> can't help but to be bothered by this behavior..
da0: <IBM DDRS-39130D DC1B> Fixed Direct Access SCSI-2 device
da0: 80.000MB/s transfers (40.000MHz, offset 15, 16bit), Tagged Queueing Enabled
da0: 8715MB (17850000 512 byte sectors: 255H 63S/T 1111C)
No problem with a 9 GB model here. Typical iostat output:
tty da0 da1 wd0 cpu
tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id
0 229 64.00 206 12.87 0.00 0 0.00 0.00 0 0.00 0 0 2 0 98
0 76 64.00 206 12.87 0.00 0 0.00 0.00 0 0.00 0 0 0 0100
0 76 64.00 205 12.81 0.00 0 0.00 0.00 0 0.00 0 0 1 0 99
0 76 64.00 204 12.75 0.00 0 0.00 0.00 0 0.00 0 0 2 0 98
0 76 64.00 206 12.87 0.00 0 0.00 0.00 0 0.00 0 0 2 0 98
0 76 64.00 205 12.81 0.00 0 0.00 0.00 0 0.00 0 0 0 0100
0 76 64.00 206 12.87 0.00 0 0.00 0.00 0 0.00 0 0 1 1 98
0 76 64.00 204 12.75 0.00 0 0.00 0.00 0 0.00 0 0 2 1 98
0 76 64.00 206 12.87 0.00 0 0.00 0.00 0 0.00 0 0 2 1 97
0 76 64.00 205 12.81 0.00 0 0.00 0.00 0 0.00 0 0 0 1 99
0 76 64.00 206 12.87 0.00 0 0.00 0.00 0 0.00 0 0 1 0 99
0 76 64.00 206 12.87 0.00 0 0.00 0.00 0 0.00 0 0 1 1 98
0 76 64.00 205 12.81 0.00 0 0.00 0.00 0 0.00 0 0 2 0 98
0 76 64.00 206 12.87 0.00 0 0.00 0.00 0 0.00 0 0 2 0 98
seems to correspond pretty well with the numbers from dd (multiple runs):
# dd if=/dev/rda0s1 of=/dev/null bs=128k count=4096
536870912 bytes transferred in 39.885097 secs (13460439 bytes/sec)
536870912 bytes transferred in 40.334386 secs (13310502 bytes/sec)
536870912 bytes transferred in 39.890058 secs (13458765 bytes/sec)
This is with an Adaptec 7890 U2W onboard controller.
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
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