From mboxrd@z Thu Jan 1 00:00:00 1970 From: "NeilBrown" Subject: Re: Write intent bitmaps Date: Sat, 20 Jun 2009 18:14:21 +1000 (EST) Message-ID: <8980e5d278405d56e8d5c128d17fe0cf.squirrel@neil.brown.name> References: <20090608021026139.GMOD14139@cdptpa-omta02.mail.rr.com> <18989.6010.582386.812296@fisica.ufpr.br> <19002.62697.475588.28776@notabene.brown> <87ab44mfn8.fsf@frosties.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: <87ab44mfn8.fsf@frosties.localdomain> Sender: linux-raid-owner@vger.kernel.org To: Goswin von Brederlow Cc: Carlos Carvalho , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Sat, June 20, 2009 1:01 am, Goswin von Brederlow wrote: > Neil Brown writes: > >> On Monday June 8, carlos@fisica.ufpr.br wrote: >>> >If so, would ext2 probably be the best choice? >>> >>> That's what the man page says. I find it strange since if it's a file >>> the filesystem shouldn't matter. Neil? >> >> The way that md writes to the bitmap file is not entirely portable >> across different filesystems. As the man page say, it is known to >> work for ext2 and ext3. Either is a fine choice. >> A new filesystem interface is being introduced in 2.6.31 as part of >> the swap-over-NFS work. I might end up using that to write to bitmap >> files, as it has the right characteristics. But that is very much in >> the future. >> >> NeilBrown > > How about support to write to a device instead of a file? One of my next little projects is to rationalise the bitmap support and make it more generic - currently you cannot use bitmaps with externally managed metadata because there is no way to say where it should go. I don't know yet how that will end up working, but it is entirely possible that it will generalise to allows the bitmap to be written to an arbitrary device. However, as bitmaps are typically quite small (a few megabytes at most, typically tens of kilobytes) it seems clumsy to create a partition just for a bitmap.. NeilBrown