[JohnnyTheA]

I have a g4 Mini and a 250 GB external USB 2.0 drive. I want to get a big firewire drive to backup my main (40 GB) Mini drive in case of failure (I can boot off of the Firewire drive). I figure I will set up a 40GB partition to image the Mini's drive every week. With the "Rest" of the Firewire drve, I was wondering if I can make it a RAID mirror of my other USB 2.0 drive. So critical data (movies, files, whatever) are saved to two places...

Is this type of setup possible? The guy at the Apple store was sort of stumped..

John

[Taskiss]

RAID is made up of multiple disks on one or more interfaces. If I read your question correctly, you want to just use one disk, which doesn't help if there's a failure and all it does is halve your storage space even if you wanted to do it.. or could do it, for that matter.

The answer is "no".

[JohnnyTheA]

No, I want to set up a RAID with two disks. One that is a USB2.0 and the other that is firewire.

John

[Ryan]

Have you poked around the RAID options in Disk Utility? I've never looked at them much myself, but maybe there's something in there that will help with your situation.

[PowerDrift]

When I created a RAID with two internal drives, I just told Disk Utility I wanted to, and dragged the disks I wanted to add to the RAID into a list. Simple as that. I imagine this could be done the same way.

[chucker]

RAID mirroring is not a backup solution.

[Taskiss]

RAID disks need to be of similar geometry - for any kind of practical configuration there will be identical numbers of heads, sectors, interface, etc.

If you just want a backup, wait for Leopard and kill 2 birds with one stone.

[JohnnyTheA]

Originally Posted by chucker RAID mirroring is not a backup solution.

Well.. Either are writable DVDs. They have a shelf life of 2-5 years and take a looonng time to burn. "Backing Up" A Terrabyte on DVD is a big job that you have to repeat every two years. A Mirror isn't the best way to go but when one drive fails, you just slap another one in and mirror away. Certainly you risk fire/flood or both drives dying at the same time. Mirroring is a good "lazy backup" solution for data that is relatively static in nature (like media). It costs twice as much as a single drive solution but is much safer. With hard drives so cheap, its becoming really popular in home (media) environments.

The best backup system is probably tape backup. But that is really expensive and involved. Just don't want to go there...

If someone has a better solution to backing up all my ripped Star Trek Episodes (yes I have the original DVDs and yes they are backups, but it takes a long time to rip and encode to mp4) let me know...

JTA

[Dave]

I think he was saying that because mirroring doesn't actually back anything up, it just, well, mirrors. If the file gets corrupted or deleted on one drive, it will on the other drive as well.

[chucker]

Exactly. DVD-Rs may not have a particularly long lifetime, but a mirror has one of exactly zero.

[ghoti]

It's not an Officially Sanctioned Backup Solution™, so what? The idea is to have the data written to two disks at the same time so that if one of the craps out, the data will still be there. I don't think that's such a bad idea. Of course, this won't save you from inadvertently deleting the wrong file, or from file corruption that's caused by software.

Having said that, I don't know if it's possible. I would guess yes, you just need two partitions of exactly the same size. Why don't you try it out and report back how it worked?

[chucker]

Originally Posted by ghoti It's not an Officially Sanctioned Backup Solution™, so what? The idea is to have the data written to two disks at the same time so that if one of the craps out, the data will still be there. I don't think that's such a bad idea.

No; it's just that I'm wary of people having a false sense of safety. It should only serve in addition to an archiving and/or cloning solution, not in place of them.

[billybobsky]

Right. You wouldn't want a raid of your main disk drive as a backup plan -- but a raid of your backup drive can be MORE fail safe...

[Taskiss]

Originally Posted by ghoti IThe idea is to have the data written to two disks at the same time so that if one of the craps out, the data will still be there.

The two different interfaces (firewire and USB), the fact that they are in two different enclosures, the fact that RAID will require the two partitions to be available when the volume is mounted or you will break the raid, the fact that if the raid array breaks it will take a 100% data write of one disk to the other (taking a significant length of time) to restore the raid volume....

This isn't a good idea. It's not practical. Even if you can do it, you shouldn't.

[The Mind]

If your happy with the firewire to just keep a copy of the USB drive google silverkeeper - its free software and works fine for keeping a synked copy of files on another drive. One thing - you may be better off using the firewire as your storage and the usb as the backup - i seem to remember firewire has faster sustained transfer rate.

Steve

[JohnnyTheA]

Maybe syncing would be easier for what I want. I really don't need to write to both drives all the time. I really just want a mirror of my data in case the primary drive goes down. That can be done in the middle of the night if I schedule it that way. I do want to stay away from backup formats that put the data into different formats though. A LONG time ago I used to span floppy disks (in DOS) to backup data. All the files would be put into what was essentially a large file that spanned all the disks. Losing or breaking one of the disks was painful.... Saving the same exact data in the same exact directory format you normally use is what I want. HDs are cheap now...

JTA