Hello,
I post this message just to help people that are struggling with the well
known repositioning problems of the SCSI 2 HP T4000 tape unit. I hope also
this message will be archived into any mailing list archive like Deja News
for future reference.
This tape has a bug in the firmware (at least up to version 1.10) that
prevents correct repositioning once every two repositioning command i.e a
sequence of command like:
mt rewind
mt fsf 1
mt rewind
mt fsf 1
fails on the second 'mt fsf 1' either by giving IO errors or simply
positioning the tape on the wrong position without any error. After the
tape has failed repositioning works well the first time (it looks like the
tape reset itself) and then fails again and so on.
After a lot of testing I found that a direct block seek causes the tape to
do some sort of hardware reset and so any subsequent file positioning
command works well i.e. a sequence of commands like:
mt rewind && mt seek 1 && mt rewind && mt any_file_positioning_command
or
mt rewind && mt seek 1 && mt rewind && mt eod && mt
any_file_positioning_command
always works. This is of course only a partial solution but should be
enough for backup scripts that only need to append at the end of the tape
and verify backups.
Bye!
Sbragion Denis
InfoTecna
Tel, Fax: +39 039 2324054
URL: http://infotecna.home.dhs.org
