Date: Sat, 28 Jul 2001 12:09:20 -0700 From: Craig Shaver <craig@ProGroup.COM> To: "Jose M. Alcaide" <jose@we.lc.ehu.es> Cc: hardware@FreeBSD.ORG, scsi@FreeBSD.ORG Subject: Re: DLT 4000 throughput and cstream Message-ID: <3B630DE0.FC696BC4@progroup.com> References: <3B62D0CF.27C12B9@we.lc.ehu.es>
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Hi, I seem to be having problems with the scsi tape driver also. (DDS3 tape unit) It may have something to do with NFS mounts. It is not the NFS transfer rate that causes the problem (I hope), but the tape seems to timeout. I am also having problems with the fxp driver and timeouts. Doing the same tape from a Solaris 8 x86 box gives terrific results. What results did you expect from your DLT? .... "Jose M. Alcaide" wrote: > > Hello, > > I am trying to maximize the data transfer rate to a DLT 4000 tape unit: > > ahc0: <Adaptec 2940 Ultra SCSI adapter> port 0xdc00-0xdcff mem 0xdffff000-0xdfffffff irq 10 at device 10.0 on pci0 > sa0 at ahc0 bus 0 target 5 lun 0 > sa0: <Quantum DLT4000 D782> Removable Sequential Access SCSI-2 device > sa0: 10.000MB/s transfers (10.000MHz, offset 15) > > I am pipelining dump(8) to cstream (ports/misc/cstream), using this > command line: > > dump 0fua - <filesystem> | cstream -v 1 -b 64k -B 1m -c 2 -o /dev/nsa0 > > However, I am getting what a I think is a too low transfer rate > (compression is enabled on the DLT unit). This is what I get with > iostat(8): > > sa0 > KB/t tps MB/s > 60.59 22 1.31 > 60.59 22 1.31 > 61.05 22 1.31 > 60.62 22 1.32 > 60.59 22 1.31 > ... > > I tried several combinations of buffer sizes to no avail. Is this the > expected throughput for a DLT 4000? If it is not, what could I do for > obtaining higher data rates? > > (Note: the disk is fast -two IBM DTLA's mirrored with Vinum-, and the > machine is an Athlon @ 800 MHz). > > TIA, > -- JMA > ****** Jose M. Alcaide // jose@we.lc.ehu.es // jmas@FreeBSD.org ****** > ** "Beware of Programmers who carry screwdrivers" -- Leonard Brandwein ** .. -- Craig Shaver, My Itty Bitty Dot Com POB 60458 Sunnyvale, CA 94088 (650)390-0654 http://www.progroup.com/ mailto:craig@progroup.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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