Date: Wed, 14 Jan 1998 11:41:47 -0800 (PST) From: "Jonathan M. Bresler" <jmb> To: sthaug@nethelp.no Cc: hasty@rah.star-gate.com, freebsd-hackers@FreeBSD.ORG Subject: Re: Any good comparison of Linux/FreeBSD/NetBSD/OpenBSD/Hurd? Message-ID: <199801141941.LAA14190@hub.freebsd.org> In-Reply-To: <6373.884772923@verdi.nethelp.no> from "sthaug@nethelp.no" at "Jan 14, 98 11:15:23 am"
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[snip] > I have a P-166 with 3.0-971225-SNAP and two IBM 4 GB disks: DCAS-34330W > (Wide SCSI), and DHEA-34330 (EIDE). As far as I know, this is really the > same disk, and it's nice and fast whether SCSI or EIDE. [snip] > # dd if=/dev/wd0s3 of=/dev/null count=5000 bs=32768 > 163840000 bytes transferred in 50.196384 secs (3263980 bytes/sec) > > # dd if=/dev/sd0s3 of=/dev/null count=5000 bs=32768 > 163840000 bytes transferred in 71.835646 secs (2280762 bytes/sec) > > and with 8k block size, I get: > > # dd if=/dev/wd0s3 of=/dev/null count=20000 bs=8192 > 163840000 bytes transferred in 175.664112 secs (932689 bytes/sec) > > # dd if=/dev/sd0s3 of=/dev/null count=20000 bs=8192 > 163840000 bytes transferred in 72.153464 secs (2270716 bytes/sec) > > So when reading through the file system the performance depends *much* > more on block size for the EIDE drive - I don't know why. But given > the right block size, *this* particular EIDE disk seems to be always > somewhat faster than the corresponding SCSI disk. please compare EIDE to SCSI when you have more than one dd running as well. two dd's to the same disk, tow dd's ot different disks on hte same controller. SCSI's ability to disconnect may prove tonmake a significant difference. jmb
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