question RAID1, removing 1 drive, data readable from removed drive?

[KrazeyKami]

Hi all,

Two simple questions:

1.
If i have a (good working) RAID1 (Mirror), and i was to remove 1 drive... and i place that drive as a single SATA in another system (provided this is not the OS / BOOT drive), will i be able to read the data?

Since in RAID1 both drives are merely copies of each other?

2.
In a related matter, what if i have a RAID0/1/5/10, and my mobo / ICH10R onboard fails, and i replace the mobo, will the new ICH10R chip pick up the array and keep my data intact?

Kind regards,
Kami.

 

[Chewy509]

1. Technically yes, but many RAID controllers will write metadata to the drive that describes the array that may confuse other RAID controllers. If using the same drive controller, then you won't have any issues.
2. Yes, it should work. (But may not due to differences in BIOS/firmware).

 

[ddrueding]

As an additional note, Chewy is correct, and it also works with the OS drive if you feel like it.

 

[LunarMist]

You should always back up regularly in any case. RAID is not a substitute.

 

[Stereodude]

1. Technically yes, but many RAID controllers will write metadata to the drive that describes the array that may confuse other RAID controllers. If using the same drive controller, then you won't have any issues.

Isn't the metadata usually at the end of the drive so it's ignored by a standard SATA controller?

 

[ddrueding]

Isn't the metadata usually at the end of the drive so it's ignored by a standard SATA controller?

RAID controllers usually play nicely as you mentioned, but I've had some SoftRAIDs mess around with the beginning of the drive.

 

[Chewy509]

Isn't the metadata usually at the end of the drive so it's ignored by a standard SATA controller?

From what I've personally seen, yes that's the case. But it's certainly not the standard that everyone follows as dd mentions.

 

[LunarMist]

Recovery testing is normally a requirement of any backup system. That is the only way to be 100% certain. :salut:

 

[blakerwry]

Apparently there's a new "standardized" way of writing RAID metadata to the hard drives - DDF. Hopefully manufacturers will pick up on it and migrating arrays between controllers, and esp manufacturers will become easier.

Looks like LSI supports it, not sure who else.

Regarding disaster recovery, RAID 1 has always had an advantage over other RAID levels in my opinion. Since all drives have a complete copy of all the data, it's pretty easy to pull a drive and be confident that you can recover the data. I've never experienced a problem moving a mirrored drive from one controller to another. Knowing this, it's pretty easy to pull a drive and keep as a backup/snapshot or migrate to newer hardware by putting a pulled drive into a new system.