On Tue, May 08, 2012 at 09:34:00PM +0200, Helmut Hullen wrote: > Hallo, Felix, > > Du meintest am 08.05.12: > > >>>> adding a bigger disk > >>>> deleting/removing a smaller disk > >>>> > >>>> with simple commands. > > [...] > > >>> Is it really possible to remove a disk from btrfs (created with -d > >>> single) without losing the data on that disk? > >> > >> When the system is configured with > >> > >> mkfs.btrfs -m raid1 -d raid0 > >> > >> then the above shown way is possible, it works (now) as expected. > >> Ok - it needs some time. > > [...] > > > What are the steps you're doing?! If this is really possible then > > there must be some sort of command that tells btrfs "Hey, I wanne > > remove this disk from the fs, please copy all data to the other disks > > and then remove the disk". Is there such a command? Haven't heard of > > one, but that would be interesting. > > btrfs device add /dev/$newdisk ... > (btrfs fi balance ...) > btrfs device delete /dev/$olddisk ... > (btrfs fi balance ...) > > I've told these simple steps many times in this mailing list. > > Since some kernel versions (at least since kernel 3.2.x) it seems to > work without problems; "btrfs-progs"-packet from 2011-10-30. > > > > Otherwise if you remove a disk from a raid0 (doesn't matter if you > > have 2 or 5 or x disks in the fs, btrfs should stripe above all > > disks) your fs should be broken. > > > Not with btrfs ... there it works even with > > mkfs.btrfs -m raid1 -d raid0 ... There is a big difference between "orderly and planned removal of a hard disk", and "disk goes away with no warning". This is essentially the difference you've been talking about at cross-purposes all day. Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- My karma has run over my dogma. ---
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