Backup 1 side of RAID to the other (incrementally?)

don't you want your backup offsite?

rsync has the abbility to sync two volumes. It is not incremental though.

It depends on what you really want. You say you want incremental. Beacuse of a full copy takes too long.

+ rsync copys only the changes, so time is proporional to the amount of change.
+ a incremental will also copy the changes, but in this case you can go back to a certain time and recover to the situation on that time. I do not know a simpple command tool which does this. The big backup software vendors (omniback, legato, ...) have it.

You decide what you need, and invest from that.

Donald your signature text certainly supports your bias

You are right about that. After 10 years of unix/linux I am doing OSX things for some time. Some of the GUI's are OK, but the xsan gui is not one of them. My primer task is administrating xsan. Hence my signature. It is not ment to offend, but to point individuals in the direction of the command line tools. Sometime I feel like I am the only cli guy in the forum.

Anyway
My idea of a backup would be a cron/launcd script which starts a rsync job.
My script is published in http://discussions.apple.com/thread.jspa?messageID=5966562&#5966562

Regards
Donald

I would think twice before relying on a striped (RAID0) drive for any kind of backup. LaCie big drives can (and often do) fail.

Don

Maybe I'm missing something but if you need incremental back-ups and off-site back-ups to run as well why not a commercial back-up program? That is pretty much their entire function.

Get one that supports Disk to Disk imaging and use it for both your local incrementals and then your off-site tape or disk or whatever you want to use there. You can mess around with rsync and tar and scripts running off of cron and all that but if you care enough to actually back-up your data I think it's one of those places that it makes sense to spend some money to get that peace of mind.

My $.02,

=Tod

You're right - I've been reading updates to the thread but hadn't read the original in a while... 😉

Some of this depends on your off-site back-up method. I would suggest tape in general but especially for >1TB of data. (Lugging disks around is not my idea of a real back-up protocol.) Tape systems usually come with some stock kind of software and if it will do disk-to-disk then you should be pretty much set.

If you're determined to roll your own solution I would start by dis-recommending Retrospect. Stay far, far away from this once great software. The two most commonly mentioned solutions in conjunction with the Xserve RAID are bakbone's NetVault (expensive) and Tolis' BRU software.

We use BRU and it works well enough but it definitely has some sharp edges and it's own quirks. It is essentially a GUI tool to extensive Unix commands underneath and will require more work from you than you might want. Like if you want to completely restore a drive to it's last back-up state but have done only incremental back-ups (with no differential) you will need all of the incremental saves and will probably be doing them by hand because there's no simple "Restore" button. Your set-up is pretty straightforward so maybe you will stress BRU less than we do but I can't wholeheartedly recommend it - especially as an easy or turnkey solution.

I priced NetVault and it was too expensive at the time - mostly because we needed 25 clients. Once we get our clients to 10.5 and the workstations can use TimeMachine our number of required licenses will plummet and I am looking to move to NetVault then.

My (additional) $.02,

=Tod

Tape formats for back-up is a discussion that comes close to religious wars but in reality there are only a couple of contenders. Most people come down in the LTO (3 or 4), DLT (several variations) or AIT camps. Each format has it's adherents and detractors but essentially each generation doubles the capacity of the previous one (like LTO-3 to LTO-4) and once you've picked one you stick with it. Most of the formats are capable of native storing in the range of 500-1000GB on a tape these days and that's really where you want to be because having a back-up fail because you weren't there to swap a tape is no good.

Most tape units come in either SCSI or fibre channel so you'll need either a SCSI card installed or an open fibre channel port either on the machine or on a fibre channel switch. (There are some firewire versions out there but when you start to break a TeraByte of data you need to keep reasonable through-put in mind or your back-ups will simply take too long.) Many units now also come with a robot loader system that allows un-attended tape swapping for large back-ups and the capability of multiple drive units for simultaneous operations. Most drive units come with some software and you need to evaluate whether it is sufficient for your needs or whether you'll need to buy something more capable.

As always it's features and speed versus price and don't forget to budget for tape expenses as time goes on you'll need to add tapes and those costs add up as well.

=Tod