On Tue, 16 Jul 2002, Simon Bryan wrote:
> At the moment the only ones being succesfully backed up are the Windows
> boxes using the built in software, these are gpoing to tape (DDS), but this
> is obvioulsy nowhere near enough. The total of data on the Windows systems
> may get up to only around 10 -20 GB.
>
> My hope is to have a backup server that is doing all the work for all the
> systems. I can do this under Windows with some expensive software and
> hardware utilising SAMBA to get the Linux based data (could work the other
> way as well). We are a school, so have a relatively large window of
> opportunity for backups to take place overnight. We do have internet access
> to the AUC system but most of this dies around mid-night and that is all web
> based access.
You're shit out of luck.
Large scale backups - regardless of platform - are hideously expensive. A
tape library {given that the largest tape drive I know of is only about a
max of 80 gig per tape} will set you back literally tens of thousands of
dollars - alternately, you get someone to change the tape when it's full,
but have to pay them wages to sit around all night waiting.
> Does there exist a sutiable robust Linux system? I would imagine that most
> of the bcakups would go to another HDD on another machine, and then to tape
> from there.
There's plenty of software to do the job. Hell, tar will do it just fine.
The problem is your hardware, as mentioned above. With that much data to
backup every night, you're going to span tapes - and you need some way to
enable this.
> We have a 128K ISDN line which could also be utilised if needed,
> but that would be last resort stuff.
80 gig over a 128k ISDN line? Every night? Are you serious?
Look at the numbers.
80 gig is 8.589934592 times 10 to the 10th power bytes.
{Someone can check my math if they like. I figured it like this
1024 bytes times 1024 equals one megabyte, or 1048576 bytes. Multiply this
by 1024 again to get a gigabyte - or 1073741824 bytes. Multiply this by 80
to get 80 gigabytes.}
A 128k line {that's 128 kiloBITS per second} will move, at most, allowing
nothing at all for protocol overhead {which would have to be included, but
I'm only looking at pure figures here} 16000 bytes per second. That's
960000 bytes per minute. Or 57600000 bytes per hour.
At that rate, moving your data would take 1491.31 hours.
Or 62 and a bit days.
> I am still relatively uninformed as to these larger backup systems processes
> and problesm so would appreciate advice from anyone doing something in a
> similar sized and configured system
If you want a daily FULL backup of everything, you're going to need a tape
changer {or a bigger tape drive than I am aware of, which may be
possible}.
What you need to consider is a backup regeim which only performs
incrimental backups for most of the week, with a full backup happening
once a week - then you will fit most of your backup on one tape daily, and
only have to worry about changing tapes once a week.
Works something like this.
Sunday - full backup
Monday - Files changed Monday backed up.
Tuesday - Files changed Monday & Tuesday backed up.
Wednesday - Files changed Monday, Tuesday and Wednesday backed up.
Thursday - Files changed Monday, Tuesday, Wednesday and Thursday backed
up
Friday - Files changed Monday, Tuesday, Wednesday, Thursday and Friday
backed up.
You can include Saturday if you want {if necessary}, or move your full
backup to Friday night to avoid one set of incrimental backups.
TAR contains the ability to to differential backups {as far as I know},
and a suitable script could be written to do this. Alternatively, you
could run something like Veritas or ArcServe on one of the WindoZe boxes,
and backup the Linux stuff via samba.
The option of backing up to another hard disk is viable, but you're going
to need a lot of disks to keep the required amount of data. Legally, if
you're backing up financial transactions, you're required to keep 15 YEARS
of backups - and if you don't, and can't provide the data if the tax
office asks for it, you're in deep do-do.
Either way, you're gonna have to spend a fair bit of money.
DaZZa
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