>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.