ULTRIUM-TD4 I/O Errors...

Dear All:

I have a SAS tape Unit Dell PowerVault LTO4-120 tape unit (Vendor: IBM and Rev: 89B2), connected to a PE2950 server with RHES 4.0u4 (Nahant Update 4).

From time to time, when basic commands like 'mt' or 'tar' are used, I got I/O errors:

$ mt rewind

/dev/tape: Input/output error.

The curious is that, the tape indeed rewinds :emotion-7:

I'm using 'stinit' comand to initialize the unit. Here stinit.def file I'm using:

# Common settings for all device types
{buffer-writes read-ahead can-bsr scsi2logical drive-buffering}

# Per-type settings
# Perform cat /proc/scsi/scsi to make sure that manufacturer and model strings
# match or the settings will not be applied correctly.
# Sample below is for IBM OEM tape drives, same settings can be used
# for all LTO drives from IBM, Quantum or HP.
# IBM ULTRIUM 4
manufacturer=IBM model="ULTRIUM-TD4" {
can-bsr scsi2logical drive-buffering
auto-lock=0
timeout=3600
long-timeout=14400
can-partitions=0
# this gives highest performance, but with old versions of st module it can
# cause problems with spaning tapes
async-writes=1
# linux does not have full LTO-4 support to set modeline properly (should be
# 0x46 for LTO4), so use device defaults instead
mode1 blocksize=0 density=0x00
}

Any ideas on this curious problem ? How can be avoided ? Any experiences ?

Does anybody knows how can I turn on compession (by hardware) for the unit ? I would like to test the 1.6T teorical.

Thank you in advance

Rodrigo.