Date: Wed, 21 Feb 2007 13:31:45 -0500 From: Kris Kennaway <kris@obsecurity.org> To: Robert Watson <rwatson@FreeBSD.org> Cc: cvs-src@freebsd.org, cvs-all@freebsd.org, src-committers@freebsd.org, Nick Hibma <n_hibma@freebsd.org>, John Baldwin <jhb@freebsd.org> Subject: Re: cvs commit: src/sbin/mdconfig mdconfig.8 mdconfig.c Message-ID: <20070221183144.GA14052@xor.obsecurity.org> In-Reply-To: <20070221111242.X80197@fledge.watson.org> References: <200702202204.l1KM4NV4037929@repoman.freebsd.org> <20070221103350.P80197@fledge.watson.org> <200702210607.08422.jhb@freebsd.org> <20070221111242.X80197@fledge.watson.org>
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On Wed, Feb 21, 2007 at 11:13:09AM +0000, Robert Watson wrote: > > On Wed, 21 Feb 2007, John Baldwin wrote: > > >On Wednesday 21 February 2007 05:36, Robert Watson wrote: > >> > >>On Tue, 20 Feb 2007, Nick Hibma wrote: > >> > >>>n_hibma 2007-02-20 22:04:23 UTC > >>> > >>> FreeBSD src repository > >>> > >>> Modified files: > >>> sbin/mdconfig mdconfig.8 mdconfig.c > >>> Log: > >>> Kris suggested that swap is a better choice as a default than malloc. > >>> > >>> MFC: 1 week > >> > >>Are you sure this should be MFC'd? While I agree with the change in > >>principle, it will cause systems currently using malloc-backed md devices > >>to mysteriously switch to swap-backed. How will this behave on systems > >>that don't have swap, such as pure diskless systems not using NFS-backed > >>swap? This isn't a strong objection per se, but it could be that rc.d > >>scripts need tweaking for diskless environments if they currently do use > >>malloc-back md devices based on that being the default. > > > >I don't think this changes the default for anything in 6.x. He changed > >the default for his patch from yesterday that made it assume a type if you > >do 'mdconfig -s <size>'. Currently you have to do: > > > >'mdconfig -a -t malloc -s <size>' or 'mdconfig -a -t swap -s <size>' > > > >but Nick changed it so just '-s <size>' implied '-a -t malloc', and now > >he's changed it to imply '-a -t swap'. > > Ah, OK. This sounds reasonable. Anyway, swap-backing can't really have a worse failure mode than malloc backing in the event that backing store becomes unavailable (e.g. no swap is configured and ram is full): malloc will already panic in that situation. Kris
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