Date: Fri, 22 Sep 1995 15:09:13 -0400 (EDT) From: Chris Vance <cvance@cfar.umd.edu> To: hardware@freebsd.org, Bruce Evans <bde@zeta.org.au> Subject: Re: Adaptech 1542 & 3Com 3c509 conflict? Message-ID: <Pine.SUN.3.91.950922145844.9679A-100000@empedocles.cfar.umd.edu> In-Reply-To: <199509221125.VAA03283@godzilla.zeta.org.au>
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On Fri, 22 Sep 1995, Bruce Evans wrote: > >I seem to have some sort of conflict between my network interface and > >scsi disks. The scsi controller is an adaptech 1542CF and the eth > >adapter is a 3c509. > > >Basically, the network is slow writing to a scsi disk, and fast the > >rest of the time. Has anyone seen this before? Can anyone suggest > >something I could do to fix the situation? > > Perhaps the scsi disk is inherently slower for the type of work given > to it by ftp. This is not unlikely, since ftp's writes are poorly > buffered and scsi disks often have a very high command overhead. I don't think this is it at all. As I mentioned, I've also run iozone while ftping a huge file to /dev/null, and the iozone results are within 100kps of the normal speeds, however the network speed plummets to 200kps. (normally ~500-600kps to /dev/null) > The speed over ethernet (WD8013EBT) for ftp'ing a 15MB file to a slow > scsi disk and to /dev/null were the same (about 440K/sec, probably > limited by the slow IDE disk on the server). This was faster than for > ftp'ing from localhost and the same speed as cp'ing from the same file > system in some cases (cases where the buffer cache cannot help and > where clustering is apparently ineffective). I just ftp'd to localhost, and got 745kps reading and writing to the same scsi disk and 1.29MB/s writing to /dev/null. I feel that it's definitely a conflict between the 3c509 and the adaptech. If anyone needs additional info to help diagnose the problem, I'm certainly willing to provide it. I really want to find a solution to this problem. chris.
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