RE: hot spare disk

Raid 6 is not a spare drive! -both- of the 'extra' drives are actively participating in the set-- keeping either data or parity information at all times. It's just an added extra when raid sets grow to 16, 24, or more drives! It lets you have 2 drives in a single set fail and still not lose data.

I think I remember hearing about a 'real' hot spare-- up and spinning but with zero data and zero parity until one of the 'live' drives fails.

--Paul E Musselman
PaulMmn@xxxxxxxxxxxxxxxxxxxx



At 8:48 AM -0400 4/29/08, Walden H. Leverich wrote:

> RAID6 isn't Raid5 with Hot Spare. RAID6 uses 2 drives woeth of parity
if

you will allowing you to loose '2' drives in the same set and still run

as you know.

Yes, but therefore the "spare" drive is "hot". That is, it's up and
running the second you lose the first one (ok, it was always running,
but the point is there is zero-unprotected time.)

In the case of RAID5 with a spare, it's "warm" at best. There is
unprotected time as the array is rebuilt.

-Walden