Efficient tape I/O with 386/ix; How??

[clewis at ecicrl.UUCP]

In article <317 at focsys.UUCP> larry at focsys.UUCP (Larry Williamson) writes:
>Streaming tape I/O with 386/ix seems to be rather slow.  The drive
>is not streaming very well.  It spends most of it's time stopping
>and starting.  I'm using an Everex Excel 60 with a long controller
>card. 
>
>The command I've used is
>	find . -print | cpio -ovc >/dev/rmt0

Try this instead
	find . -print | cpio -ovcC1048576 >/dev/rmt0

Mentioned in the HCR release notes.  Can be retrofitted into the
sysadm backup and restore scripts if you want (the HCR note contains
details of which files and where to fix).

Another alternative which works in most 386 UNIXs (not Xenix) is piping
the output of your program thru dd with a bs of 1mb.  Eg:

	tar cvf - <files> | dd bs=1024k > /dev/rmt0

(Xenix dd can't handle that much bs ;-)

Similar tricks are also useful for speeding up cpio's, tar's or similar
programs to floppies.

Bell Tech UNIX (actually a somewhat older version of 386/ix) had utilities
such as "star" and "stream".  All they were were pipes of some utility
thru a program with a large (default 3Mb!) buffer.
-- 
Chris Lewis, Markham, Ontario, Canada
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