PV-124T shoe shining on PE2950

[Fred Skrotzki]

Double check all termination settings and if possible change from "Automatic" to hard set values.  Each end of the SCSI chain needs to be terminated (That means the end of the Tape Library loop and at the Card.  When a SCSI chain is short things can appear to "work" but not properly or at full speed if the termination is not set correct.  The more devices on the chain the higher the likelyhood that errors will be seen and felt as each device starts to speak at different times causing more noise on the lines and then termination issues quickly become apparent.  This might not happen in your case as the Library robot is a very low volume device that speaks once in a blue moon.

-----Original Message-----
From: linux-poweredge-bounces at dell.com [mailto:linux-poweredge-bounces at dell.com] On Behalf Of Jesús M. Navarro
Sent: Monday, March 05, 2007 7:13 AM
To: linux-poweredge at dell.com
Subject: PV-124T shoe shining on PE2950

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

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).  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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