Question about security of Mirroring drive data

[m021478]

I am considering the purchase of an OWC Mercury Rack Pro RAID 0+1 FW800 & USB 2.0 Stripe & Mirror 4 Bay Rack Storage Solutions (http://eshop.macsales.com/shop/hard-drives/RAID/Rack_Mount/FireWire_USB2_RAID_0_1) but I had a question about "Mirroring" in general as a backup/redundancy mechanism...

Mirroring basically creates a mirror image of any data on a drive as it's created (on the physically seperate mirrored drive)...the idea being that if the drive get's corrupted you will always have the mirrorred copy as a backup...

But what happens if it's not the actual drive that gets corrupted, but rather some of the data on the drive...then you would basically have a corrupted copy of the data on both the primary drive and the mirrored drive, correct?

Any suggestions would be greatly appreciated...Thanks!

[iBookG4user]

Yes, that is correct. If a file gets corrupted then that corrupted file would get copied from one drive to the other. Same if you delete a file, it would be deleted on both.

[TuffLuffJimmy]

That's why mirrored drives along with DVD back ups are a great solution. It'd also be smart to use a file system like zfs that can repair certain data corruptions.

[Cliff3]

But what happens if it's not the actual drive that gets corrupted, but rather some of the data on the drive...then you would basically have a corrupted copy of the data on both the primary drive and the mirrored drive, correct?

That's where Time Machine would come in, since presumably that file-level corruption would occur at some point in time and your goal would be to restore from a pre-corrupted version of that file. A mirrored drive protects you from hardware faults, while versioned backups help to protect you from software failures.

[m021478]

Faulty hardware can lead to a corruption of drive data, correct? If this happened, then wouldn't the corrupt data also be mirror to the second disk, even if that physical drive didn't have any hardware faults?

[TuffLuffJimmy]

Faulty hardware can lead to a corruption of drive data, correct? If this happened, then wouldn't the corrupt data also be mirror to the second disk, even if that physical drive didn't have any hardware faults?

Sure, but again, there are some file systems that can check for these corruptions and fix them. Anyway, most file systems can detect bad blocks and just skip over them. So data corruption in the way that you're suggesting is very rare these days.

[jrlcopy]

I am considering the purchase of an OWC Mercury Rack Pro RAID 0+1 FW800 & USB 2.0 Stripe & Mirror 4 Bay Rack Storage Solutions (http://eshop.macsales.com/shop/hard-drives/RAID/Rack_Mount/FireWire_USB2_RAID_0_1) but I had a question about "Mirroring" in general as a backup/redundancy mechanism...

Mirroring basically creates a mirror image of any data on a drive as it's created (on the physically seperate mirrored drive)...the idea being that if the drive get's corrupted you will always have the mirrorred copy as a backup...

But what happens if it's not the actual drive that gets corrupted, but rather some of the data on the drive...then you would basically have a corrupted copy of the data on both the primary drive and the mirrored drive, correct?

Any suggestions would be greatly appreciated...Thanks!

Sorry for digging up an old post, but don't ever buy from this company. ESPECIALLY these drives, 3 out of 3 had issues, caused bluescreen errors when hooked up to PC's. Data was destroyed (thank god for backups), hard drive failures, and more.

I trusted buying from them since they are the 'go-to' place for off market memory/hard drives, etc for macbook's, but, never again. 3 out of $%# 3.

You would have thought that this was a user error thing, but I've had certified techs/engineers look at them.