Date: Thu, 28 Apr 2011 07:25:21 +1000 From: Peter Jeremy <peterjeremy@acm.org> To: Freddie Cash <fjwcash@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: Why not just name the cam-ata devices the same as the old names? Message-ID: <20110427212521.GA99261@server.vk2pj.dyndns.org> In-Reply-To: <BANLkTinSEg90d4=YaKfLZLKVOLn_si6LSg@mail.gmail.com> References: <4DB70949.6090104@FreeBSD.org> <20110426182017.GA92471@freebsd.org> <4DB70F13.6060002@FreeBSD.org> <BANLkTikFHLaQ=Vrt9UhyJdo5ELm522OZjA@mail.gmail.com> <4DB759A1.4050201@FreeBSD.org> <BANLkTinSEg90d4=YaKfLZLKVOLn_si6LSg@mail.gmail.com>
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--cNdxnHkX5QqsyA0e Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2011-Apr-26 22:46:20 -0700, Freddie Cash <fjwcash@gmail.com> wrote: >This is where labelling *disks* is the better route. Filesystems come >and go, but the disks don't change very often. This is one the nicest >things about using FreeBSD systems (all the GEOM stacking and >labelling). But disks _do_ get changed for various reasons (eg failure). If we move to a an identification approach that is based on the physical disk, rather than some variant on the path to a disk, we need to ensure that the disk replacement procedure is well documented. One associated issue is determining what disk you are booting from - my main system has 6 disks spread across 3 controllers. Whilst the BIOS reports size and model, it doesn't report serial number (and the mapping of SATA port to legacy PATA channel/master-slave is non-obvious and as tripped me up in the past). By the time I get to loader(8), I'm just presented with 'C' through 'H' (mapped to disk0 thru disk5). There is no way to map this to either physical disk (though this is probably the fault of my BIOS) or to FreeBSD device names. loader needs to grow enough smarts to be able to report a disk serial number (where possible) and there nees to be a tool that can map between loader and FreeBSD disk names (though it's not clear whether this belongs in loader(8), the kernel, userland or some combination). As for the ad->ada renaming: I went through this some time ago (by manually switching my kernel from ata to ahci), resulting in ad{4,6,8} becoming ada{0,1,2}. Whilst I was aware of the issue, I still managed to confuse myself and I think it took me at least one reboot to get the names straight. (Thought ZFS took the renaming of the devices underlying my data pool in its stride). --=20 Peter Jeremy --cNdxnHkX5QqsyA0e Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (FreeBSD) iEYEARECAAYFAk24icEACgkQ/opHv/APuIcvqgCcCe7p4SWQf7CVdec8PodQPFSb fbMAoLMKBFtIt//aFxc2XlRuKCLEPtcx =kao1 -----END PGP SIGNATURE----- --cNdxnHkX5QqsyA0e--
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