Date: Thu, 14 Oct 1999 16:55:45 -0600 (MDT) From: "Kenneth D. Merry" <ken@kdm.org> To: jpsp@rccn.net (Joao Pagaime) Cc: scsi@FreeBSD.ORG Subject: Re: FreeBSD 3.2 / Slow SCSI Dell PowerEdge 4300 Message-ID: <199910142255.QAA46124@panzer.kdm.org> In-Reply-To: <Pine.BSF.4.10.9910141552550.15842-100000@atlas.rccn.net> from Joao Pagaime at "Oct 14, 1999 03:53:13 pm"
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--ELM939941744-46065-0_ Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Joao Pagaime wrote... > > I have a very slow Pentium III/450 with 512MB RAM > because disks tranfers are slow. > > Simple tests show a transfer rate of +/- 2MB/sec, > when a PC with IDE can do easily at least 4 times > that value. > > I think the problem is with the "Common Access Method" > in the backplane, because although the controllers are > found with no problem : > > ahc0: <Adaptec aic7890/91 Ultra2 SCSI adapter> rev 0x00 int a irq 11 on > pci2.4.0 > ahc0: aic7890/91 Wide Channel A, SCSI Id=7, 16/255 SCBs > ahc1: <Adaptec aic7860 SCSI adapter> rev 0x03 int a irq 11 on pci2.6.0 > ahc1: aic7860 Single Channel A, SCSI Id=7, 3/255 SCBs > > The backplane is reported as having only 3.3 MB transfer rate : > > pass2 at ahc0 bus 0 target 6 lun 0 > pass2: <DELL 1x6 U2W SCSI BP 5.12> Fixed Processor SCSI-2 device > pass2: 3.300MB/s transfers > > Did anyone experience the same problem ? > Can someone help me ? > Any hints ? > Any configurarion at the CAM level ? - I configured the kernel > to debug CAM but I can only reboot the machine in a few > hours... Other folks already explained the 3.3MB/sec transfers on your backplane device, so i won't repeat what they said. > PS: the disks are also reporter correctly : > > da1 at ahc0 bus 0 target 1 lun 0 > da1: <WDIGTL WDE9180 ULTRA2 1.20> Fixed Direct Access SCSI-2 device > da1: 80.000MB/s transfers (40.000MHz, offset 31, 16bit) > da1: 8687MB (17793001 512 byte sectors: 255H 63S/T 1107C) > > da0 at ahc0 bus 0 target 0 lun 0 > da0: <WDIGTL WDE9180 ULTRA2 1.20> Fixed Direct Access SCSI-2 device > da0: 80.000MB/s transfers (40.000MHz, offset 31, 16bit) > da0: 8687MB (17793001 512 byte sectors: 255H 63S/T 1107C) Western Digital drives generally aren't that great. In fact, we have disabled tagged queueing for most all Western Digital SCSI drives. (including the drives you have, above) [ ... ] > Dell PowerEdge 4300 > (http://www.dell.com/products/poweredge/pe4300/index.htm) > > time dd bs=1000000 count=100 if=/dev/zero of=t > 100+0 records in > 100+0 records out > 100000000 bytes transferred in 53.853144 secs (1856902 bytes/sec) Okay, there are several things to try here: - first, enable write caching on this drive if it isn't already turned on. camcontrol modepage da0 -m 8 -P 3 -e Then change the 'WCE' bit from 0 to 1. Do the same thing for da1. - if your performance doesn't improve after that, try re-enabling tagged queueing. Try the attached patch for src/sys/cam/cam_xpt.c. It is against -current, but I think it'll apply to 3.2. If not, you can probably see what you need to comment out. Hopefully, one of those two things will fix your performance. I'd like to hear what happens. Ken -- Kenneth Merry ken@kdm.org --ELM939941744-46065-0_ Content-Type: text/plain; charset=US-ASCII Content-Disposition: attachment; filename=cam_xpt.c.wde_tag.101499 Content-Description: cam_xpt.c.wde_tag.101499 Content-Transfer-Encoding: 7bit ==== //depot/FreeBSD-ken/src/sys/cam/cam_xpt.c#2 - /a/ken/perforce/FreeBSD-ken/src/sys/cam/cam_xpt.c ==== *** /tmp/tmp.46108.0 Thu Oct 14 16:54:28 1999 --- /a/ken/perforce/FreeBSD-ken/src/sys/cam/cam_xpt.c Thu Oct 14 16:52:13 1999 *************** *** 360,365 **** --- 360,366 ---- { T_DIRECT, SIP_MEDIA_FIXED, samsung, "WN34324U*", "*" }, /*quirks*/0, /*mintags*/0, /*maxtags*/0 }, + #if 0 { /* * Slow when tagged queueing is enabled. (1.5MB/sec versus *************** *** 371,376 **** --- 372,378 ---- { T_DIRECT, SIP_MEDIA_FIXED, west_digital, "WDE*", "*" }, /*quirks*/0, /*mintags*/0, /*maxtags*/0 }, + #endif { /* * Slow when tagged queueing is enabled. (1.5MB/sec versus --ELM939941744-46065-0_-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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