9track solutions

[b]

Hello World!
	I would like to thank all of those who responded to the request for
help with the 9track tapes.  We seem to have ironed out most of the problems.
A quick summary of the responses follows:

	1)	Block size:  Most of the responses suggested checking the
		block size.  I did.  The backup program was using the
		default cpio block size (512)!  I ran some tests and found
		that 32k was the best (although 64k was about the same).
		AT&T does recommend 32k for the 9track.  If anyone else
		is using the sysadm menus for backup, the changes could
		be added to /etc/savecpio.

	2)	Raw Device:  Make sure you are using raw i/o rather than
		blocked.  We were so there was no problem there.

	3)	Network:  There will be a slowdown due to the bandwidth
		of RFS TCP/IP being less than the SCSI bus.  We had expected
		this but we also knew that using the 9track tape should
		be as fast or faster than cartridge, even with the network.
		The performance improvements we have seen so far seem to be
		much more acceptable.  We will know for sure after the
		backups are run this weekend.

	4)	Streaming Mode:  One of the drives that AT&T OEM's is an
		HP 7980 that needs to have a bit set inorder to be in
		streaming mode.  However, our drive is a Perkin-Elmer
		model (apparantly AT&T OEM's drives from 3 manufacturers
		according to one of the responses).  I'm not sure if it
		has this bit but things seem to be smooth now so I'm assuming
		(we all know what that does :-) that if it does have it then
		it is set properly.

	I ran some tests and found that with the proper block size, writing
to the tape (still across the ethernet) took about 1/4 to 1/3 of the time
and the tape was not stopping and starting nearly as much (more writing took
place on each pass!).  I also discovered that the backup programs were backing
up our news spool directory!  We have it on one disk on our 700 machine (as it
has the most space available) and have it mounted on the 622 via RFS.  I had 
to fiddle with the /etc/savecpio script again to make sure that the dirlist
variable doesn't contain the news directory (using fgrep -v to remove anything
with /usr5 in its path since /usr5 contains all the news).  If you want to
do this yourself, keep in mind that there are two places where the changes
have to be made, once for complete backups and once for incrementals.

	Thanks to the respondents (so far!):
	Steve Friedl (3B2-kind-of-guy)
	Paul Novorolsky
	Steve Paddock
	Robert Wilhite
	Micheal East
	Arthur Gentry
	and to all those whose replies may be on the way!

	Thanks
		Bill