[fishguy]

I'm new to RAID and need some advice. For a G% to be purchased in the near future I am going to add additional internal HD as well as an external SATA array.

My questions:

1) I'm going to do RAID 0 for 2 internal drives as a scratch disk (Apple disk utility) - how prone to failure is RAID 0? Would using a single large-capacity drive be better although slower?

2) Raid 1, as I understand it, links 2 drives, one as the master and the other as the back-up and anything saved to the master is also saved to the back-up? This sounds like a slow way to set up data archiving. Would it not be faster for day-to-day use to use Retrospect or other software to back up data overnight rather RAID 1?

3) For a back-up external array, I am looking at either a 2 or 3 SATA drive enclosure. Should I use RAID to combine the 2 or 3 drives together or not? I will want to back-up the scratch disk as well as a disk for completed projects. Or is it better to keep the drives independant of each other and back-up from one drive in the G5 to one drive in the external enclosure?

4) Any better ideas?

thanks

[tooki]

1) "RAID" 0 does increase the likelihood of failure, since the failure of any drive in the array causes the entire array to be lost. (I say "RAID" in quotes because RAID 0 is in no way redundant -- on the contrary.) For just scratch space, it's certainly fine, but I personally wouldn't trust anything but disposable data to a RAID 0.

2) At least when using a proper RAID controller, the writes are done in parallel, slowing it down slightly. But then reads can be divided across both disks (since each holds a complete copy), which can actually speed some things up. Doing a separate backup most certainly takes more time than using RAID 1, but remember that RAID IS NOT A BACKUP!!!!!! RAID exists strictly to protect against drive failure. Any of the other causes of data loss (human error, buggy software, crashes, sabotage, etc) will be dutifully copied by the RAID as well.

3) Back up using what, Retrospect? A cloning tool? What kind of backup do you seek?

tooki

[legacyb4]

Agreed.

RAID-0 as a scratch would be good, but failure on either hard disc will result in loss of data and is not generally recommended for anything other than fast, fast disc access.

RAID-1 is redundant but "backup" in the proper sense of the word since, as Tooki says, it's a synchronized array so deleting data removes it from the array and not the master or slave drive only (your system only sees one virtual drive and not the two separate physical drives).

If you have important data to backup, probably RAID-1 on your system/data drives for your live system would be sufficient unless you need screamingly fast speeds. Plan on backing up your important data regularly to a third hard drive (think external Firewire or USB 2.0) in addition to burning data to DVD-R/CD-R.

[fishguy]

So I guess I should skip RAID 1 and simply use the external drives with Retrospect to back-up my scratch and storage disks. I think I'll go with a 2-bay external enclosure and go big (300-400) and leave them as standard drives.

Retrospect is simply the one software I know, anything else that you can recommend? I am looking to automate what I can in an intelligent way. Automatically copy any files/projects that have been changed since the last back-up.

What are the odds of a drive failure in RAID O? I was planning on moving the Apple 250 (Hitachi?) to a bracket along with another one and setting them up as a RAID 0. It will be used to dump and edit video mostly and I suppose I could use it for a photoshop scatch disk as well. Completed projects would get moved to a single storage drive and the RAID 0 would be backed-up regularly to th external drives.

thanks for your help!

[legacyb4]

Mean time between failure on drives these days is pretty high so theoretically is shouldn't be a problem, but there's no way to tell if the delivery guy at the store was having a bad day and dropped the box full of hard drives...

Again, I think that you should use RAID-0 if you need the sheer speed, but be mentally prepared that the you could lose everything if there's a problem.

Originally posted by fishguy:
What are the odds of a drive failure in RAID O?