Raid 0 + Backup

[Oishlam]

Wondering if there's a Raid number for when you have 3 drives - two in Raid 0 and one serving as backup for your RAID array.

 

[drtweak]

Nope. First off ANY drive that is in a RAID is NOT a backup it is a Redundancy Fail Over. There is a difference.

BUT in your case this is how you would acheive what you want.

Make a RAID 0 of two drive (MUST BE HARDWARE RAID!)

Then make a Software RAID 1 in Device manager of that RAID 0 (Which will be shown as one drive) and then make a new mirrored volume with the other drive (MUST be the same size or bigger as the main RAID 0

That is how you would do what you want.

otherwise adding 1 more drive gives you a RAID 10. It is a RAID 0 of Two RAID 1's. So as long as both drives in the same RAID on don't fail you will be fine. What i said above is NOT a raid 10 as a RAID 4 requires min 4 drives, adding 2 drives to keep expanding, of the same size.

Honestly though I would make the so called backup drive its own drive and use a program like Macrium Reflect to clone it over. The reason being, and this is why RAID, even RAID 1 is NOT a backup, is if the file system get corrupt, or a file is delete etc, its gone on BOTH drives. That is NOT a backup.

 

[ss202sl]

Some raid controllers allow a spare, so you could do what you're asking about. Be aware that if you don't check the status of the raid, it can fail without you knowing it. I had a server at a clients office with a raid 5 plus a single hot spare. He wasn't monitoring the server, and he lost a drive, which failed over to the hot spare. He eventually lost a couple other drives, and his system died. He didn't eve know the first drive had failed because he wasn;t monitoring it.

 

[USAFRet]

Wondering if there's a Raid number for when you have 3 drives - two in Raid 0 and one serving as backup for your RAID array.

Mostly, RAID 5
https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_5
Stripe, with a parity drive.
Not a true 'backup', because the 2 x in RAID 0 will be larger than the 3rd. So not a real 'backup.

Now....why are you considering doing this?