Bug#675934: st - slow tape read/write rate

Package: linux-2.6
Version: 2.6.32-41squeeze2

*** Please type your report below this line ***
Hi,
I have slow tape read/write rate after upgrade from Lenny with the old
kernel 2.6.18 to Squeeze. Everything worked well except the tape library
HP StorageWorks MSL 4048 Ultrium 960, connected to it via SCSI Megaraid
320-2x. It has become very slow. If I had read/write speeds were about
40MB/s before upgrade, now they are reduced to 1.5 MB/s. I ​​checked
speed by "tar" and "dd". Both show the same low rate. I comlied "st"
module with debug option. Here is the log:

Jun 4 14:09:36 s1 kernel: [2323441.578082] st: Version 20081215, fixed
bufsize 32768, s/g segs 256
Jun 4 14:09:36 s1 kernel: [2323441.580272] st 2:1:4:0: Attached scsi
tape st0
Jun 4 14:09:36 s1 kernel: [2323441.580297] st 2:1:4:0: st0: try direct
i/o: yes (alignment 4 B)
Jun 4 14:09:37 s1 kernel: [2323442.279534] scsi_id[5933]: segfault at 0
ip (null) sp 00000000ffcd29a0 error 14
Jun 4 14:09:37 s1 kernel: [2323442.938002] scsi_id[5930]: segfault at 0
ip (null) sp 00000000ffc0cf60 error 14
Jun 4 14:17:39 s1 kernel: [2323925.226299] st0: Block limits 1 -
16777215 bytes.
Jun 4 14:17:39 s1 kernel: [2323925.228885] st0: Mode sense. Length 11,
medium 0, WBS 10, BLL 8
Jun 4 14:17:39 s1 kernel: [2323925.228906] st0: Density 44, tape
length: 0, drv buffer: 1
Jun 4 14:17:39 s1 kernel: [2323925.228925] st0: Block size: 0, buffer
size: 4096 (1 blocks).
Jun 4 14:17:58 s1 kernel: [2323943.450101] st0: Number of r/w requests
1000, dio used in 1000, pages 8000.


- Package-specific info:
** Version:
Linux version 2.6.32-5-amd64 (Debian 2.6.32-41squeeze2)
(dannf@debian.org) (gcc$) (gcc version 4.3.5 (Debian 4.3.5-4) ) #1 SMP
Mon Mar 26 07:00:19 UTC 2012

** Model information
sys_vendor: Supermicro
product_name: X6DH8
product_version: 0123456789
chassis_vendor: Supermicro
chassis_version: 0123456789
bios_vendor: Phoenix Technologies LTD
bios_version: 6.00
board_vendor: Supermicro
board_name: X6DH8
board_version: PCB Version

** Loaded modules:
Module Size Used by
st 37924 0
megaraid_mbox 22904 10
megaraid_mm 6449 1 megaraid_mbox
scsi_mod 126021 7 st,sr_mod,sg,ch,sd_mod,megaraid_mbox,libata

Debian Release: 6.0.4
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: i386 (x86_64)

Kernel: Linux 2.6.32-5-amd64 (SMP w/2 CPU cores)
Locale: LANG=ru_RU.CP1251, LC_CTYPE=ru_RU.CP1251 (charmap=CP1251)
Shell: /bin/sh linked to /bin/bash

Versions of packages linux-image-2.6.32-5-amd64 depends on:
ii debconf [debconf-2.0] 1.5.36.1 Debian configuration
management sy
ii initramfs-tools [linux 0.98.8 tools for generating an
initramfs
ii linux-base 2.6.32-41squeeze2 Linux image base package
ii module-init-tools 3.12-2+b1 tools for managing Linux
kernel mo

Versions of packages linux-image-2.6.32-5-amd64 recommends:
ii firmware-linux-free 2.6.32-41squeeze2 Binary firmware for various
driver
ii libc6-i686 2.11.3-3 Embedded GNU C Library:
Shared lib

Versions of packages linux-image-2.6.32-5-amd64 suggests:
ii grub 0.97-64 GRand Unified Bootloader
(dummy pa
pn linux-doc-2.6.32 <none> (no description available)

Versions of packages linux-image-2.6.32-5-amd64 is related to:
pn firmware-bnx2 <none> (no description available)
pn firmware-bnx2x <none> (no description available)
pn firmware-ipw2x00 <none> (no description available)
pn firmware-ivtv <none> (no description available)
pn firmware-iwlwifi <none> (no description available)
ii firmware-linux 0.28+squeeze1 Binary firmware for various
driver
ii firmware-linux-nonfree 0.28+squeeze1 Binary firmware for various
driver
pn firmware-qlogic <none> (no description available)
pn firmware-ralink <none> (no description available)
pn xen-hypervisor <none> (no description available)



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