Help required - Breaking Raid 1?

[Pants-Of-Fire]

I'm about to venture into some RAID on an Asus P5Q Deluxe (ICHR10 + Silicon Image controller). I've only got a couple of drives, and in the course of messing with some different stuff, I'm going to be resetting single drives, copying data about to convert the AICH drives to RAID without reinstallation, and breaking and migrating RAID 1 a few times to install XP and then later Win7 whilst keeping backups of an older boot drive.

My main question is that if I have two drives in RAID1 as a boot device, can I break the array and still have two single boot drives for use in RAID mode? Can I just disable one drive without losing all the data? If so what is the best way to do this, as the Matrix Storage Manager docs seem to be a little vague on the matter and implies that all data will be lost if I mark a drive as non-raid.

Or should I just power off and disconnect a drive in order to keep a working boot disk as backup while I erase the other disk to install new OSes? I'm trying to avoid buying a third drive for backup (after all, that's what RAID1 is for, right?) or else I'd just try it out, but I don't want to risk losing all my data off both drives just by dropping one of the drives out of the array.

Thanks for any help/advice :D

[stevecs]

Umm. First, raid 1 is NOT for backup at all. No raid levels are for backup, they are all for hardware availability which is completely different. Though unsilvering a mirror and using the individual drive is possible it is NOT one of the functions of raid (i.e. it's a hack) and it may work depending on where the raid volumeset information is stored by your controller. If stored at the beginning of the drive your data will still be on there but you won't be able to boot it.

If you un-plug a drive from a raid-1 array (say as you mention to keep as a copy) the problem is that as soon as you plug that drive back in to the raid the live drive will overwrite all the data on the other drive.

If your concern is for data backup, you need a backup solution. Either buy another drive and copy your data to it (or use utilities like acronis, ghost, whatever) or a tape backup solution, but in any case it's not raid.

[Pants-Of-Fire]

Ah right. Thanks for clarifying things, looks like I need another drive after all. You made a very good point about the difference between "availability" and "backup". I've gained an understanding and am now more likely to be using the right tool for the job!

[Pants-Of-Fire]

As a followup if anyone is interested.... I didn't need another disk. With a bit of switching cables around and using the secondary controller, I converted my AICH drives to RAID drives under ICH10R without OS reinstallation. According to the docs, when you break a RAID 1 array, you don't lose the data, and end up with two boot disks running in passthrough RAID mode. Later, this will allow me to break the RAID1, install Win7 to one disk, copy the static data from the second disk, and then re-migrate the RAID from the first disk over to the second disk.