Disk Striping (VMS and Unix)

[hosking at convexs.UUCP]

All currently supported versions of Convex's port of 4.2 BSD support disk
striping.  We also support basic disk block sizes of up to 64 KB, and some
asynch file I/O features.  These can be used together for an even greater
performance boost.  99.9% of all user programs don't know or care that
striping is being used.  Except for the increased performance, striping is
virtually transparent to the user, too.  (There are a few trivial changes to
fstab, and a new file called /etc/stripecap, but this is no big deal.)

Striped file systems are built using a utility called newst, which is very
similar to newfs, but builds striped file systems.  Newst allows you to
stripe together any reasonable combination of partitions.  (The root
partition can't be striped, for technical reasons.)  Once a striped
partition is built with newst, it is mounted as /dev/stxx instead of
/dev/daxx, using a different major device number.  It can then be
accessed just like any "normal" partition.  

Another, less obvious feature of striping is that it gives you increased
flexibility with partition sizes.  If you have several "a" partitions that
are too small to be useful, you can stripe them together to form a larger
partition, without the need to edit kernel tables, recompile, etc.

I really don't want to turn this into a commercial for Convex.  If you have
questions, I'll be happy to try to answer them and/or refer you to our
sales people.

			Doug Hosking
			Convex Computer Corp.
			Richardson TX
			{allegra, ihnp4, uiucdcs}!convex!hosking