Date: Thu, 2 Sep 1999 23:05:43 +0200 (CEST) From: Remy Nonnenmacher <remy@synx.com> To: freebsd-scsi@freebsd.org Subject: ccd peak performance Message-ID: <199909022105.XAA12981@gw0.boostworks.com>
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I ran in a strange 60MB/s barrier somewhere and would like to have some highlight about it : I use a machine with 3 PCI buses, each bus with 3 U2W-LVD SCSI channels. All disks deliver a little more than 20MB/s (Quantum 18.2). Whatever CCD configuration I try, I get a 60MB/s peak read performance per CCD. I tried 4,5 and 6 disks, on various channels, on various PCI busses, etc...: Can't get more than 60MB/s. Using two CCD on same controller pull up perf to 72MB/s (which is near the channel bandwidth). Using 3 CCD's on different channels takes me to a little more than 160MB/s (and 2 CCD's on different channels give me about 120MB/s. Peak perf with all disks active (direct read) is 175MB/s). Any guess where does that 60MB/s/CCD limit comes from ? (Performance numbers with vinum also welcome). Additional Infos: 3.2-STABLE, Intel C440GX+ SMP Bi-Xeon 500, 2x3950U2W (channel A used) + Internal 7896 controller. TIA. RN. ItM To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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