[759] in linux-scsi channel archive
large block sizes with SCSI tape drives
daemon@ATHENA.MIT.EDU (Baba Z Buehler)
Fri Nov 3 23:54:03 1995
Reply-to: Baba Z Buehler <baba@beckman.uiuc.edu>
From: Baba Z Buehler <baba@beckman.uiuc.edu>
To: linux-scsi@vger.rutgers.edu, linux-kernel@vger.rutgers.edu
Date: Fri, 03 Nov 1995 18:17:12 -0600
I'm doing some speed trials on a DLT tape drive for evaluation purposes, so
I've been playing with block sizes, etc to see how they affect operation of the
drive.
I noticed that in 1.3.37, when I use a block size of 200k or more (using dd
if=large.file of=/dev/nst0 bs=200k) it instantly freezes the system... there
_may_ be a null pointer Oops produced in this, nothing gets logged, but I did
see what looked like part of an Oops on one of the VCs when I did this from
text mode instead of while running X. Using bs=100k or less seems to work
fine.
I tried these operations under 1.2.13, and it seems that anything over 32k for
a block size is invalid.
Is there a maximum block size the Linux SCSI tape drive can write, and, if so,
where is this defined? (I poked around in drivers/scsi/st.c for a bit, but
didn't see anything obvious there.)
Thanks,
--
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# Beckman Institute Systems Services, Urbana Illinois
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