On Tue, Jul 16, 2002 at 11:59:01AM +1000, Simon Bryan wrote:
> Hi all,
> I now have (or will soon have) up to 180GB of user data I need to backup,
> currently it is under 4GB but users have just been given much larger home
> directories that I am sure they will fill, as well I am adding a 70GB drive
> for curriculum resources.

Simon,

Unfortunately, every situation is different - my solution may not work for you, and it 
may work for Dazza....

Being a school, do you need to do weekend backups ?  Here's the schedule I use at work 
(an Insurance company with something like 42 odd (VERY odd !!) Windows boxen in the 
computer room)....

One important thing to realise is the difference between a DIFFERENTIAL and an 
INCREMENTAL backup (I still get them confused at times).

Differential only backups up what's changed from one day to the next (i.e. Monday's 
differential will backup Monday's changed files. Tuesday's differential will backup 
any files that have changed between Monday and Tuesday, etc...)

Incremental is a progressively longer backup each day (i.e. Monday's incremental backs 
up Monday's changed files. Tuesday's incremental backs up Monday's changed files PLUS 
Tuesday's changed files... etc....

So - here's what we use - a 4 week tape rotation cycle, with a permenant FULL backup 
taken on the last working day of the month (if the month finishes on a Friday, 
Saturday or Sunday - this backup is Friday night, if it finishes mid-week, then the 
first Friday of the following month). The permenant tapes are archived off-site for 10 
years (when we probably won't be able to read the bloody things anyway).

Monday night - Incremental - Monday's files
Tuesday night - Incremental - Monday's files, Tuesday's files
Wednesday night - Incremental - Monday's files, Tuesday's files' Wednesday's files
Thursday night - Incremental - Monday's files, Tuesday's files, Wednesday's files, 
Thursday's files
Friday night - FULL BACKUP - all archive bits reset

The following week the cycle repeats on tape set #2 - this continues for 4 weeks, then 
set 1 is re-cycled (which is after the permenant full backup is taken, usually but not 
always)

This means that a restore SHOULD require only one tape, or a full and an incremental 
in some circumstances.

I started this system 3 years ago and it hasn't failed yet, although the cost of tapes 
is pretty high initially, it's saved our bums a few times (especially when Windows 
lusers delete their home drive "No, I didn't delete it - it must have been the 
network...")

A possible option for you, with the availability of cheap 160Gb+ drives these days, is 
a backup server with 100Mb full duplex (or gigabit if you can afford it !!) which 
"mirrors" the data from your main server overnight, and then backups can be done from 
this box during the day.

Of course, a backup server with a removable drive caddy, configured (for example) as 
/dev/hdb, with a few removable drives (one per day) would be a faster, but probably 
more expensive, option than the backup server/tape combo...

As for software, I've had good results with Arkeia, BRU, and (believe it or not) 
ArcServe for Linux - but I still fall back to good ol' tar or cpio for most of the 
work....

Hope this gives you a few ideas - contact me off-list if you want the obscenely 
Windows-based details of our system...:-)

Jon

-- 
SLUG - Sydney Linux User's Group - http://slug.org.au/
More Info: http://lists.slug.org.au/listinfo/slug

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