We saw the same thing earlier this year with a new STK tape library with
IBM FC ULTRIUM2 drives with the same firmware (38D0).  This library is
connected to both an AIX p630 and HP L2000 servers.  I wrote a perl program
to simulate the networker saves (2Gb files of 64Kb blocks) and report times
and rates.  The normal file write was around 63 seconds with occasional
files taking up to 600 seconds.  We got rid of the sympton by switching to
the IBM Atape.driver which doesn't have a write timeout that the default
tape driver has.  The HP server didn't timeout and so didn't show the
problem.

All this was documented and submitted to STK who then submitted it to IBM.
I havn't got back any resolution from STK or IBM other than they are looking
into it.

The STK tech indicated they had seen problems traced to static in the tapes
and that after the tapes are used a few times the problems went away.  I
also noticed the problems are not consistent.  Different spots on the tape
with different passes.  Even had days with no failures (long write times)
and then lots of failures the next day on the same tape and tape drive.

What we did was to use drivers with no (or very long) write timeouts.  Other
than the backup will ocassionally stall for several minutes, everything is
running and the tapes are filling up (300-500Gb per tape).


On Mon, 19 Jul 2004 12:09:30 +0200, Maarten Boot (CWEU-USERS/CWNL)
<Maarten.Boot AT NL.COMPUWARE DOT COM> wrote:

>Networkers,
>
>Last week I wrote a small perl program to verify my LTO-2 tapes.
>I needed it after too many LTO tapes were marked full between 20 and 50 GB.
>On some tapes (not all) I see some interesting time differences on an
>otherwise idle machine
>
>Hardware used:
>
>Sun E450 with 2 400 Mhz CPU, 1 GB mem
>scsi card:  LSILogic LSI22320-R
>Exabyte 110L with IBM ULTRIUM2 drives (firmware: 38D0)
>
>data written is a 128k block of gzipped random data from /dev/random

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