Date: Tue, 09 Feb 2010 22:13:08 +0100 From: "Ronald Klop" <ronald-freebsd8@klop.yi.org> To: "Freddie Cash" <fjwcash@gmail.com>, freebsd-stable@freebsd.org Subject: Re: zpool vdev vs. glabel Message-ID: <op.u7vo76dc8527sy@212-123-145-58.ip.telfort.nl> In-Reply-To: <b269bc571002090910y506b1938ld5983b0d5f3e05e1@mail.gmail.com> References: <20100209150606.ddba52dc.gerrit@pmp.uni-hannover.de> <20100209142658.GA38072@icarus.home.lan> <b269bc571002090910y506b1938ld5983b0d5f3e05e1@mail.gmail.com>
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On Tue, 09 Feb 2010 18:10:21 +0100, Freddie Cash <fjwcash@gmail.com> wrot= e: > On Tue, Feb 9, 2010 at 6:26 AM, Jeremy Chadwick =20 > <freebsd@jdc.parodius.com>wrote: > >> Also, I'm a little confused as to the use of glabel in this case. In >> what condition do your disk indices (e.g. X of daX) change? Are you >> yanking multiple disks out of a system at the same time and then shovi= ng >> them back into different drive bays? Are you switching between storag= e >> subsystem drivers (ahci(4) vs. ataahci(4), for example) regularly? >> >> I've yet to be convinced glabel is worth bothering with, unless the >> system adheres to one of the above situations (which are worthy of >> strangulation anyway ;-) ). >> >> Use multiple disk controllers in a server, and watch as kernel updates > and/or BIOS updates change the order that the controllers are probed, =20 > thus > changing the dev node for every disk in the system. > > Use multiple disk controllers that use CAM, then move from an IDE-based > CompactFlash adapter to a SATA-based CompactFlash adapter for the / > filesystem, and watch the system renumber all your dev nodes. > > Use a RAID controller configured for JBOD or "Single Disk" arrays, and > replace a drive while the server is running, which assigns the disk =20 > "largest > da number +1", then renumbers everything when the server reboots. > > After you run into those kinds of things a few times, you'll start to u= se > glabel(8) for everything. Plus, it just makes things easier to =20 > understand. > Instead of da0 through da25 which is a mix of SATA, RAID, and USB =20 > drives, > you have cfdisk0, cfdisk1, disk00 through disk24, and so on. > > Personally, the greatest thing to ever happen to FreeBSD is the =20 > introduction > of GEOM, and the addition of the glabel class. :) Yeah. GEOM is very very very nice. It is a very elegant solution to a lot= =20 of problems. I always wonder why other OS'es didn't pick it up. Ronald. > While ZFS does it's own disk labelling behind the scenes, using glabel = =20 > just > makes things easier.
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