Backup verification

[r.peterson]

>From article <737 at visdc.UUCP>, by jiii at visdc.UUCP (John E Van Deusen III):
> The real performance problems come from the the pipes, IPC.  It was
> bad form for me not to remove all that I could, (although I seem to
> count just as many pipelines in the second version).  In particular
> dd if=/dev/ct bs=5120 | sum will never beat sum < /dev/ct.

Probably not - if sum were smart enough to do block reads at the correct
blocksize.  Its' not.

In fact, several tape device drivers that I've used forbid reads smaller
than a block - as an attempt to reduce possible noise conditions, I
believe.  BSD43 unix is a perfect example of this.

-- 
One makes strong assumptions delving	       Roe Peterson
into the beginning of the universe...	       {uunet,mcgill-vision}!sobeco!roe
	- Stephen Hawking, Cambridge