Re: Raid 5 to 6 migration

On 02/01/2013 01:49 PM, Chris Murphy wrote:

On Feb 1, 2013, at 11:19 AM, Phil Turmel [off-list ref] wrote:

quoted

On 02/01/2013 01:16 PM, Roman Mamedov wrote:

quoted

--layout=preserve will make it an order of magnitude faster. Read "man mdadm"
for more details. (And "man md" to learn about things in general.)

But will leave the array "unbalanced"--the 7th drive will never be used
for reads in normal (non-degraded) operation--reducing read performance.

Does this option mean, in effect, the 7th disk is just a parity disk? So, sorta like a hybrid RAID 5/RAID4.

Yes, with just the Q left on the 7th disk.  The remainder of the array
is the normal raid5 stripe.  See the manpage for the layout
"left-symmetric-6".

Phil