[CentOS] RAID 6 - opinions

Thu Apr 11 15:51:30 UTC 2013
Joseph Spenner <joseph85750 at yahoo.com>

>From: "m.roth at 5-cent.us" <m.roth at 5-cent.us>

>To: CentOS mailing list <centos at centos.org> 
>Sent: Thursday, April 11, 2013 8:36 AM
>Subject: [CentOS] RAID 6 - opinions
>I'm setting up this huge RAID 6 box. I've always thought of hot spares,
>but I'm reading things that are comparing RAID 5 with a hot spare to RAID
>6, implying that the latter doesn't need one. I *certainly* have enough
>drives to spare in this RAID box: 42 of 'em, so two questions: should I
>assign one or more hot spares, and, if so, how many?

A RAID5 with a hot spare isn't really the same as a RAID6.  For those not familiar with this, a RAID5 in degraded mode (after it lost a disk) will suffer a performance hit, as well as while it rebuilds from a hot spare.  A RAID6 after losing a disk will not suffer.  So, depending on your need for performance, you'll need to decide.
As far as having a spare disk on a RAID6, I'd say it's not necessary.  As long as you have some mechanism in place to inform you if/when a disk fails, you'll not suffer any performance hit.