PV-124T shoe shining on PE2950

[Christopher McCrory]

On Mon, March 5, 2007 4:12 am, Jesús M. Navarro wrote:
> Hi all:
> I've got a new PE2950 2GB RAM with an Adaptec 39230A which links to a
> PV124T
> LTO2.  That's the only device on that SCSI chain, since disks (2xRAID1 +
> 4xRAID5) are attached to a PERC5/i.  The operative system is Debian "Etch"
> amd64 (that's the arch for all x86_64 CPUs).
>
> The problem is that I can't make the tape stream, it just shoe shines at
> about
> 2MB/s.
>
> For instance:
>
> time -p dd if=/dev/zero of=/dev/tapenorewind bs=64k count=16384
>

a string of zeros compresses fairly well.  Did you turn off tape HW
compression?


> This should move data to the tape as fast as possible but the drive seems
> to
> stream for some three/four seconds then stops for about ten seconds and
> then
> starts again, so the overall result is being terribly slow (as I said, it
> averages at about 2MB/s).
>
> I tested this both moving zeroes as in the previous example as well as
> moving
> a 2GB file (a dump image) or data directly from a partition, either with
> dd,
> dump or tar with exactly same results, so I think it must be some issue
> either with the tape drive itself or some config parameter regarding the
> Adaptec.  Moving data from disk to disk (ie. from the RAID5 array to the
> RAID1) averages a bit over 30MB/s which seems reasonable (while not
> brilliant).

IIRC,
U320 scsi can move 320Mbits/sec which is close to your 30MB/s


  I already upgraded the firmware both for the drive and the
> tape
> changer just in case.
>
> Any help or ideas?
> --
> Jesús M. Navarro
> Jefe de Sistemas y Soporte
> Ándago Ingeniería - www.andago.com
>
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-- 
Christopher McCrory
 "The guy that keeps the servers running"

chrismcc at pricegrabber.com
 http://www.pricegrabber.com

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