SCSI tape access on 2.6 kernels?

[Gerhard Schneider <gs@ilsb.tuwien.ac.at>]

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It's getting me mad..

It seems that with 2.6 (compared to 2.4) there has something been
changed in the kernel that I'm not aware of so I'm not able to
write/read tapes efficiently anymore..

LSI1030 SCSI controller
Overland tape library
Seagate LTO-1 tape drive

Kernel 2.4.29:

dd if=linux-2.6.16-rc1.tar.gz of=/dev/nst0 bs=64k
776+1 records in
776+1 records out
50918460 bytes transferred in 4.620612 seconds (11019852 bytes/sec)

Kernel 2.6.14rc1:

dd if=linux-2.6.16-rc1.tar.gz of=/dev/nst0 bs=64k
776+1 records in
776+1 records out
50918460 bytes transferred in 20.395567 seconds (2496545 bytes/sec)

Another machine w/
LSI1030 SCSI controller
Megaraid ZCR controller
Overland tape library
HP LTO-3 tape drive
Kernel 2.6.14rc1:

dd if=linux-2.6.16-rc1.tar.gz of=/dev/nst0 bs=64k
776+1 records in
776+1 records out
50918460 bytes transferred in 45.953133 seconds (1108052 bytes/sec)

Either there is an initialization problems with tape drives on 2.6.*
(I don't think so) or there are tunable kernel parameters that
I don't know..

CPU load on 2.6 is minimal, tape is waiting for data..

Any idea? (I can provide you with any amount of data etc..)

                                            GS

-- 
Gerhard Schneider
Institute of Lightweight Design and          e-Mail:gs@ilsb.tuwien.ac.at
Structural Biomechanics (E317)                 Tel.:   +43 1 58801 31716
Vienna University of Technology / Austria      Fax:    +43 1 58801 31799
A-1040 Wien, Gusshausstrasse 27-29     http://www.ilsb.tuwien.ac.at/~gs/

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