Ed's probably on point--slow DLTs and LTOs are usually repositioning
because they're not fed well enough to stream. Adjusting driver parms
can help, so can various forms of buffering. Also see "star"
manpages--it was written to replace tar, with streaming drives in mind.
See the fifo option in particular.
Ed K. wrote:
On Tue, 14 Dec 2004, Tom Haws wrote:
I'm having problems adding an Exabyte Magnum LTO-2 tape device to my
RHL 9 machine. I know that's a different OS, so thius question should
go in the shrike lists, but it's close enough to Fedora that I thought
I might get some answers here, and the shrike lists are just about
dead now. Red Hat announced the end of RHL 9 2 months after I
installed a production server on it... arrrghh...
Anyway, after I add the device, it shows up fine in /proc/scsi/sci,
and I can write to it, but it is extremely slow. I got about 30MB
written in 5 minutes! Has anyone else had any experience with LTO-2
devices on Fedora or RHL 9 systems, and is there anything I can do to
recreate device files or anything to speed it up?
Also, do you know if I do a "mknod -m 666 /dev/st0 c 9 0" with the
tape drive hooked up, does it do anything different than if there
wasn't one installed? Like read the status bits on the drive to tell
what it's capabilities are?
Tom,
I have a similar problem on a DLT-1 on a FC1 computer, and had problems
with speed until I found the proper way to write to the tape. Here are
the commands to prime the tape:
modprobe st buffer_kbs=1024 max_buffers=128 max_sg_segs=128 blocking_open=1
mt setblk $[64*1024]
#test
tar -cf - .|mbuffer -s $[64*1024] > /dev/tape
mbuffer -s $[64*1024] < /dev/tape > /dev/null
You can find mbuffer at:
http://directory.fsf.org/All_Packages_in_Directory/mbuffer.html
ed
