Compressing to a tape drive
John Plocher
plocher at sally.Sun.COM
Fri Mar 9 08:48:51 AEST 1990
+-- In <14496 at s.ms.uky.edu> acp at ms.uky.edu (ACPNET consultant) writes
| This is on an AT&T 6386 WGS running Sysv/386 3.2.1.
|
| find . -print | cpio -oc | compress | dd [blocking options] > /dev/rmt/c0s0
| it, but I haven't been able to find any dd options which let the
| tape stream. It keeps stopping and backing up. When using something
| like ibs=32k obs=512 (the tape writes 512-byte records), dd reports
+--
Try something like
find . -print | cpio -oc | compress | dd of=/dev/rmt/c0s0 -obs 1024k
this writes 1Mb at a time to the tape - and the drive *will*
stream. Don't worry about tape blocking - the QIC tapes are
set up to do all blocking internally, unlike the 9 track reel
tape drives you may be familiar with...
You may also want to explore the different cpio options avaliable:
-I rawdevice which selects the Input device,
-O rawdevice which selects the Output device, and
-C size which specifies a blocking size
-I and -O will detect end of tape and prompt you to change tapes
and press return when ready to continue ...
find . -print | cpio -oc -O /dev/rst/c0s0 -C 102400
Lastly, there are several programs on the net that are replacements
for either cpio (afio), or dd (ddd) which allow double buffering,
multi-process buffering, ... which may be another solution to your
problems...
-John
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