From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: very degraded RAID5, or increasing capacity by adding discs Date: Tue, 23 Oct 2007 18:41:15 -0400 Message-ID: <471E788B.7000001@tmr.com> References: <20071008211313.6cd8bbb5@absurd> <470AB496.5010406@msgid.tls.msk.ru> <18186.62585.7261.178442@notabene.brown> <470B4E82.6010102@msgid.tls.msk.ru> <20071022090300.GA22588@apartia.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20071022090300.GA22588@apartia.fr> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Louis-David Mitterrand wrote: > On Tue, Oct 09, 2007 at 01:48:50PM +0400, Michael Tokarev wrote: > >> There still is - at least for ext[23]. Even offline resizers >> can't do resizes from any to any size, extfs developers recommend >> to recreate filesystem anyway if size changes significantly. >> I'm too lazy to find a reference now, it has been mentioned here >> on linux-raid at least this year. It's sorta like fat (yea, that >> ms-dog filesystem) - when you resize it from, say, 501Mb to 999Mb, >> everything is ok, but if you want to go from 501Mb to 1Gb+1, you >> have to recreate almost all data structures because sizes of >> all internal fields changes - and here it's much safer to just >> re-create it from scratch than trying to modify it in place. >> Sure it's much better for extfs, but the point is still the same. >> > > I'll just mention that I once resized a multi-Tera ext3 filesystem and > it took 8hours +, a comparable XFS online resize lasted all of 10 > seconds! Because of the different way these file systems do things, there is no comparable resize, at least in terms of work to be done. For many systems R/W operations are more common than resize, so the F/S type is selected to optimize that. ;-) -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979