Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!mimsy!eneevax!umd5!brl-adm!adm!lewis@cel.fmc.COM
From: lewis@cel.fmc.COM (Bil Lewis)
Newsgroups: comp.unix.wizards
Subject: On backups
Message-ID: <7272@brl-adm.ARPA>
Date: Thu, 7-May-87 08:45:04 EDT
Article-I.D.: brl-adm.7272
Posted: Thu May  7 08:45:04 1987
Date-Received: Sat, 9-May-87 03:30:46 EDT
Sender: news@brl-adm.ARPA
Lines: 59


	Starting about six months ago I implemented a rather different
backup technique (which is completely unique to the best of my
knowledge) that you might find interesting.

				-----

	My site at FMC comprises some 16 unix machines of various
sizes & vendors. I have a total of about 4GB active storage in 60 or so
partitions.  Using standard unix backup procedures, this entailed ~60
tapes * 9 days for incrementals and a very harassed operator.  Level 0
dumps were really a terror.  [As a matter of fact, many got "lost" on
bad days.]  Restores were a pain.

	We purchased a new Eagle, and today backups are done as follows:

Incrementals:	At 2am, each machine tars up all the new user files
(ignoring .o, .psf, .tmp, ... files) and ships them to the Eagle where
they are kept for a month.  Any missed backups are noted by a script
and can be collected the next day.

Full dumps:	At 3am, one machine is choosen to do a complete dump of
some of its partitions to the Eagle.  These are then written to tape by
the operator, one copy on site, one off.  That partition is cleared &
ready for the next day.

Restores:	From an incremental I just look for the file in the
associated directory files & then restore it from whatever daily it was
on.  [The users could even do their own restores if you trusted them
enough!]

		From a full dump, just load the tape to the scratch
partition, then restore normally.


	The advantages are obvious: Zero time spent on making
incrementals, near immediate access for recent restores, no holes in
the incrementals due to operator error/time problems/heavy dates on
Sundays/etc.  Full dumps are a simple routine and don't require any
down time, and there is also no problem if an operator misses a day;
the full dump just waits on the scratch disk (sending me nasty
messages) until dumped to tape.  By also dumping the incrementals to
tape, I get 100% backup capacity to restore for any day over the entire
year!

	The disadvantages may be more subtile: Do I lose anything by
not bringing the system down to single user level for the full dumps?
Do I lose any security by having the incrementals on-line?  [I think
not.  It requires TWO simultanious head crashes to lose anything & I've
never head of such a thing.]

				--------

	At this point in time I conclude this to be a case of extreme
winning.  For the price of an Eagle (~$10k), I save one operator-year
(~$50k), gobs of tapes, storage, hassles, and improve reliability
enormously.

-Bil