Whilst I certainly agree that there is a lot that can be recreated or
re-installed, saying NO as you suggest is commercial suicide,
irrespective of the operating system.
Having managed a large computer room in Sydney of 40+ servers running,
if you'll pardon the profanity, Windows NT, our backups got up to about
200Gb at one stage. For those interested, here's how we did it - and
we're talking Insurance data here, which can be subpoena'd in court at
any time;
This applies to ANY operating system, certainly Linux and outer *NIX
varients as much as Windows.
Using a 4 week cycle and incremental backups daily, each tape had a
"live" time of 4 weeks before recycling. At the end of each month, a
FULL backup of the entire dataset was taken and archived in permenant
storage off-site... Here's the tape cycle
Week 1 Monday Incremental backup - all file changes since last Friday
Tuesday Incremental backup - Monday's backup plus all
files changed since Monday
Wednesday Incremental backup - Tuesday's backup
plus all files changed since Tuesday
Thursday Incremental backup - Wednesday's backup
plus all files changed since Wednesday
Friday FULL BACKUP and archive bits reset.
Weeks 2, 3 and 4 were indentical, each week on their own set of tapes.
Generally one tape per day was sufficient, but as the Notes email
databases grew, we got to 2 tapes per day on Thursday, and sometimes
Wednesday. Friday was generally always two tapes.
The only things backed up were those identified as DATA - home
directories, Notes email databases, etc. No programs were backed up
(they could be re-installed if needed, although any config files were
kept), except for the full backup on Fridays when the backup would run
into Saturday or even Sunday on rare occasions. The general rule was
that backups had to finish by 0600 the next day.
At the end of each month, the FRIDAY backup became the MONTHLY FULL
BACKUP, and was kept permenantly off-site. The way the MONTHLY backup
was executed was;
If the month ends on a Friday, Saturday or Sunday, then that FRIDAY was
the monthly backup.
If the month ended mid-week, then the first Friday of the next month
became the full backup.
In the above example, we were using 7 tapes per week x 4 weeks, plus
another 2 - 3 tapes for the monthly permenant. DLT tapes were about $110
each, so the investment was certainly not insignificant. When data
tended to go over 1 tape on a regular basis, another was simply thrown
into the cycle. Compression, which is much bad mojo as far as I'm
concerned (but the decision was my PHB's, not mine), was supposed to be
2:1 but on things like Notes mail files I rarely got more than about
1.25:1 on a good day.
This was certainly a very secure way of handling backups for our
business, but this procedure isn't ideal for everyone - it is very much
dependant on the criticallity of the data being backed up, and how
valuable it is to your business. Hourses for courses, I guess...
Jon
=> On Sat, Jan 18, 2003 at 07:21:19AM +1100, [EMAIL PROTECTED] wrote:
=> >
=> > There are DLT drives which do 80 gig - maybe 100,
=> although I haven't
=> > seen
=> [ .. ]
=>
=> If I'm not mistaken, the number in DLT whatever e.g. DLT80
=> refers to the capacity after compression, assuming 2x
=> compression, which is typical.
=>
=> There is DLT20, 40, or 80. I believe DLT160 s are coming
=> out real soon now.
=>
=> The best approach to backing up is usually to say no.
=> Surprisingly little data on many machines is not
=> recoverable or reproducable or that inportant in the first place.
=>
=> Next best approach is to only do it incrementally, forever.
=> I.e. use rsync to remote copy. The only thing this
=> doesn't give you is to go back to a point in time easily.
=>
=> Whatever you do, compare the cost of backing up versus the
=> probability of losing the data times the cost of losing the data.
=>
=> Matt
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