Using RAID 1 as a method of cloning

[John Gray]

Any thoughts on the following Windows drive cloning suggestion?

1) put an identical drive into your PC and set up (software) RAID-1
2) break the mirror
3) remove the original drive and boot from the newly-cloned drive

I feel that there may well be flaws...

[Leif]

In theory that should work - that's what it's meant to do, isn't it? It's certainly my first line of recovery, should the need arise!

I had a server (some years back) that had Raid 1. The first drive started disintegrating. I removed it, re-configured Drive 1 to be Drive 0, and it (re-)started normally (apart from an initial complaint that a drive was missing).

I don't think you should expect normal HD performance, particularly with software Raid 1, and especially on first starting up as everything is copied from Drive 0 to Drive 1....

[John Gray]

Thanks, that's what I thought, but I've never had to do it in anger since if any file gets corrupted on a (bad) first disk, this gets copied across to the (good) second disk, doesn't it?

[StuartR]

Thanks, that's what I thought, but I've never had to do it in anger since if any file gets corrupted on a (bad) first disk, this gets copied across to the (good) second disk, doesn't it?

Yep. RAID 1 only protects you from hardware errors, any software corruption will happily get mirrored to both disks.

[Leif]

Any corrupted data will happily get backed up to any clone or backup, and from experience, it can be some years before you are aware that what you thought was a safe copy has been unusable for a decade.

I would assume that if there is hardware corruption making part of one drive unreadable, the Raid software would not attempt to duplicate it. But I can't be sure.

I don't think there is an easy (i.e. cheap) solution to protecting yourself against instantaneous recovery from data corruption as it happens.

Unless you know better?

[John Gray]

Unless you know better?

How on earth could I ever know better than you, O Leif?!