Subject: Reading DLT does not stream?
To: NetBSD Users <>
From: Jukka Marin <>
List: netbsd-users
Date: 09/01/2004 11:13:31
Hi (again),

I used gtar to backup a bunch of files on a DLT tape.  Using pkgsrc/buffer,
the DLT drive was streaming >99% of the time.

However, when I try reading the tape, I can't make it stream.  The drive
reads a few megabytes, rewinds the tape, reads some more, rewinds etc.
This is slow and sounds like a good way for killing a DLT drive.  Is this
a feature of DLT drives or something I can fix?

NetBSD 2.0_BETA (XSERVER20) #0: Tue Aug 31 21:35:05 EEST 2004
total memory = 1023 MB
avail memory = 996 MB
cpu0: AMD Athlon XP 2600+ (686-class), 1915.36 MHz, id 0x6a0
esiop0 at pci0 dev 10 function 0: Symbios Logic 53c875 (ultra-wide scsi)
esiop0: using on-board RAM
esiop0: interrupting at irq 11
scsibus0 at esiop0: 16 targets, 8 luns per target
st1 at scsibus0 target 10 lun 0: <HP, DLT VS80, 583B> tape removable
st1: drive empty
st1: sync (100.00ns offset 15), 16-bit (20.000MB/s) transfers

It doesn't matter whether I do "gtar tvf" or "gtar xvf", so it's not
disk speed causing the rewind.  This doesn't help, either:

buffer -m 10m -p 10 -i /dev/rst1 -t | gtar tvf -

Just in case I want to read the backup tapes sometime.. I'd like it to
work faster and not kill the drive ;-) :-(  I'd also like to see if the
24 GB file is restored properly.