SUN level zero backup

[Chris Torek]

In article <11570 at brl-adm.ARPA> dnb at brandeis.csnet (David N. Blank) writes:
>... Currently, we do level zero backups for our twelve odd SUN (2/3)
[twelve is even, but I suppose a Sun two-thirds is odd :-) ]
>workstations (running NFS) over our ethernet (via rmt) to our standard
>DEC tape drives residing on a VAX.  This takes an eternity ....
>Surely there must be a better way.

There is one better way that is very cheap, although it requires
that you have 4.3BSD on one of those Vaxen.  Take your 4.3BSD
/usr/src/etc/dump and compile and install it on your Suns.  (Keep
the old /etc/dump and /etc/rdump in case of emergency.  Note also
that Sun links /etc/rdump to /etc/dump, Sun having noticed that
rdump can write local files just as easily as can dump.)  Next,
increase the `tcp_sendspace' variable on your Sun kernels to (at
least) 8K, and reboot:

	% su
	Password:
	# adb -w /vmunix /dev/kmem
	tcp_sendspace/D
	tcp_sendspace:
	tcp_sendspace:		4096
	tcp_sendspace/W 0t8192
	tcp_sendspace:
	tcp_sendspace:		4096	=	8192
	.?W 0t8192
	tcp_sendspace:
	tcp_sendspace:		4096	=	8192
	$q
	# shutdown ...
	# fastboot

Now run rdump and note that it goes at least twice as fast.
If you leave out the tcp_sendspace step, however, it will
run at a mere five tape blocks per second.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at mimsy.umd.edu	Path:	uunet!mimsy!chris