From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Harold Subject: Re: from 2x RAID1 to 1x RAID6 ? Date: Tue, 07 Jun 2011 19:59:34 -0400 Message-ID: <4DEEBB66.7080802@nybeta.com> References: <4DEE6A11.1030205@xunil.at> <4DEE84F0.2030205@harddata.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4DEE84F0.2030205@harddata.com> Sender: linux-raid-owner@vger.kernel.org To: Maurice Hilarius Cc: lists@xunil.at, linux-raid@vger.kernel.org List-Id: linux-raid.ids On 6/7/2011 4:07 PM, Maurice Hilarius wrote: > On 6/7/2011 12:12 PM, Stefan G. Weichinger wrote: >> Greetings, could you please advise me how to proceed? >> >> On a server I have 2 RAID1-arrays, each consisting of 2 TB-drives: >> >> .. >> >> Now I would like to move things to a more reliable RAID6 consisting of >> all the four TB-drives ... >> >> How to do that with minimum risk? >> >> .. >> Maybe I overlook a clever alternative? > > RAID 10 is as secure, and risk free, and much faster. > And will cause much less CPU load. > Well, with both a pair of RAID1 arrays and a pair of RAID-10 arrays, you can lose 2 disks without losing data, but only if the right 2 disks fail. With RAID6, any two of the four can fail without data loss. (I still prefer RAID-10 over RAID-6 unless space is at an absolute premium. But for a four-disk setup, net disk space is the same and it's just a question of whether you want the speed of RAID-10 or the reliability of RAID-6.)