[comp.unix.xenix] afio and tape streaming

chaiklin@cunixf.cc.columbia.edu (Seth Chaiklin) (07/25/90)

I have been learning to use afio to do backups to tape cartridges.
One of the options is -c to set the number of buffers to use.
The man page recommends a "large number" when using a streaming
tape backup, but it does not specify a specific value.  I am
curious/interested in recommendations.  Also, I thought that it
was possible to do multi-volume backups with afio, but I did not
succeed with a "cat filelist|afio -o -f -s59m /dev/tape"

I am running SCO Xenix/386 2.3.1 and an Everex (Wangtek) 60 Mb drive.

Thanks for the advice.

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Seth Chaiklin         Institute for Learning Technologies
(212) 678-3899        Box 8, Teachers College, Columbia University, NYC 10027
INTERNET:  chaiklin@cunixf.cc.columbia.edu    UUCP:  seth@ny-yn
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caf@omen.UUCP (WA7KGX) (07/28/90)

Here's a command I use. The /tmp/DONE business assures that all the
files get on the tape even if the south end gets wasted.

cp /etc/termcap /tmp/DONE
date >/tmp/today
find /tmp/today . /tmp/DONE -print | /u/caf/bin/afio -ovzb 32k -s 62m /dev/rct0
tape status
tape rewind

The real buffering is in the tape driver.  SCO 3.2 makes the tape stream
most of the time, except for directories with zillions of tiny files.
Xenix FS is slower; try using a 1 meg buffer so the tape doesn't backup
so often.