From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: raid10 on three discs - few questions. Date: Wed, 06 Feb 2008 17:13:56 -0500 Message-ID: <47AA3124.6080202@tmr.com> References: <20080203235043.3dbb6433@szpak> <18342.18975.229866.860765@notabene.brown> <47A9FFE1.5070001@tmr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Jon Nelson Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Jon Nelson wrote: > On Feb 6, 2008 12:43 PM, Bill Davidsen > wrote: > > Can you create a raid10 with one drive "missing" and add it later? I > know, I should try it when I get a machine free... but I'm being > lazy today. > > > Yes you can. With 3 drives, however, performance will be awful (at > least with layout far, 2 copies). > Well, the question didn't include being fast. ;-) But if he really wants to create the array now and be able to add to it later, it might still be useful, particularly if "later" is a small time like "when my other drive ships." Thanks for the input, I thought that was possible, but reading code isn't the same as testing. > IMO raid10,f2 is a great balance of speed and redundancy. > it''s faster than raid5 for reading, about the same for writing. it's > even potentially faster than raid0 for reading, actually. > With 3 disks one should be able to get 3.0 times the speed of one > disk, or slightly more, and each stripe involves only *one* disk > instead of 2 as it does with raid5. I have used raid10 swap on 3 or more drives fairly often. Other than the Fedora rescue CD not using the space until I start it manually, I find it really fast, and helpful for huge image work. -- Bill Davidsen "Woe unto the statesman who makes war without a reason that will still be valid when the war is over..." Otto von Bismark