From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Kuzminsky Subject: Re: Raid sync observations Date: Wed, 21 Dec 2005 10:02:31 -0700 Message-ID: References: <43A8B623.5060704@nighthawkrad.net> <20051221114912.GY10278@strugglers.net> Return-path: In-reply-to: <20051221114912.GY10278@strugglers.net> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Andy Smith wrote: > On Wed, Dec 21, 2005 at 12:55:47PM +1100, Christopher Smith wrote: > > Why would you use RAID6 and not RAID10 with four disks ? > > I was wondering the same thing. It's true that RAID6 is guaranteed > to still run degraded after losing 2 devices, whereas a RAID10 on 4 > devices could only lose 1 device from each RAID1. So there is some > small extra redundancy there. That's the reason - better reliability. With 4-disk RAID-10, a 2-disk failure has a 1/3 chance of causing array failure. With RAID-6, there is no chance. > But how does the performance for read and write compare? Good question! I'll post some performance numbers of the RAID-6 configuration when I have it up and running. -- Sebastian Kuzminsky