From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Greaves Subject: Re: limits on raid Date: Fri, 22 Jun 2007 13:39:34 +0100 Message-ID: <467BC306.9010008@dgreaves.com> References: <18034.479.256870.600360@notabene.brown> <18034.3676.477575.490448@notabene.brown> <46756BE2.7010401@tmr.com> <467B03C1.50809@tmr.com> <18043.13037.40956.366334@notabene.brown> <467B840F.4080402@dgreaves.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: david@lang.hm Cc: Neil Brown , Bill Davidsen , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org List-Id: linux-raid.ids david@lang.hm wrote: > On Fri, 22 Jun 2007, David Greaves wrote: > >> That's not a bad thing - until you look at the complexity it brings - >> and then consider the impact and exceptions when you do, eg hardware >> acceleration? md information fed up to the fs layer for xfs? simple >> long term maintenance? >> >> Often these problems are well worth the benefits of the feature. >> >> I _wonder_ if this is one where the right thing is to "just say no" :) > so for several reasons I don't see this as something that's deserving of > an atomatic 'no' > > David Lang Err, re-read it, I hope you'll see that I agree with you - I actually just meant the --assume-clean workaround stuff :) If you end up 'fiddling' in md because someone specified --assume-clean on a raid5 [in this case just to save a few minutes *testing time* on system with a heavily choked bus!] then that adds *even more* complexity and exception cases into all the stuff you described. I'm very much for the fs layer reading the lower block structure so I don't have to fiddle with arcane tuning parameters - yes, *please* help make xfs self-tuning! Keeping life as straightforward as possible low down makes the upwards interface more manageable and that goal more realistic... David