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 13:43:45 -0500 Message-ID: <47A9FFE1.5070001@tmr.com> References: <20080203235043.3dbb6433@szpak> <18342.18975.229866.860765@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <18342.18975.229866.860765@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: Janek Kozicki , linux-raid@vger.kernel.org List-Id: linux-raid.ids Neil Brown wrote: > On Sunday February 3, janek_listy@wp.pl wrote: > >> Hi, >> >> Maybe I'll buy three HDDs to put a raid10 on them. And get the total >> capacity of 1.5 of a disc. 'man 4 md' indicates that this is possible >> and should work. >> >> I'm wondering - how a single disc failure is handled in such configuration? >> >> 1. does the array continue to work in a degraded state? >> > > Yes. > > >> 2. after the failure I can disconnect faulty drive, connect a new one, >> start the computer, add disc to array and it will sync automatically? >> >> > > Yes. > > >> Question seems a bit obvious, but the configuration is, at least for >> me, a bit unusual. This is why I'm asking. Anybody here tested such >> configuration, has some experience? >> >> >> 3. Another thing - would raid10,far=2 work when three drives are used? >> Would it increase the read performance? >> > > Yes. > > >> 4. Would it be possible to later '--grow' the array to use 4 discs in >> raid10 ? Even with far=2 ? >> >> > > No. > > Well.... if by "later" you mean "in five years", then maybe. But the > code doesn't currently exist. > That's a reason to avoid raid10 for certain applications, then, and go with a more manual 1+0 or similar. 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. -- 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