From mboxrd@z Thu Jan 1 00:00:00 1970 From: Goswin von Brederlow Subject: Re: Write intent bitmaps Date: Sat, 20 Jun 2009 11:52:30 +0200 Message-ID: <87ws77cjvl.fsf@frosties.localdomain> 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> <8980e5d278405d56e8d5c128d17fe0cf.squirrel@neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: In-Reply-To: <8980e5d278405d56e8d5c128d17fe0cf.squirrel@neil.brown.name> (NeilBrown's message of "Sat, 20 Jun 2009 18:14:21 +1000 (EST)") Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: Goswin von Brederlow , Carlos Carvalho , linux-raid@vger.kernel.org List-Id: linux-raid.ids "NeilBrown" writes: > 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 lvcreate --extents 1 ... Ideal would be if one could put multiple bitmaps on the same device. But then again that is what an FS allows. MfG Goswin