From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Samuel Subject: Re: multiple device usage Date: Mon, 29 Dec 2008 23:52:29 +1100 Message-ID: <200812292352.33059.chris@csamuel.org> References: <556243856@web.de> <200812292232.08037.chris@csamuel.org> <3d0408630812290433r7f2bb07cue3239c8acf958bb3@mail.gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1324315.X8rPFgaIUn"; protocol="application/pgp-signature"; micalg=pgp-sha1 To: linux-btrfs@vger.kernel.org Return-path: In-Reply-To: <3d0408630812290433r7f2bb07cue3239c8acf958bb3@mail.gmail.com> List-ID: --nextPart1324315.X8rPFgaIUn Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Hello Yan, On Mon, 29 Dec 2008 11:33:18 pm Yan Zheng wrote: > 2008/12/29 Chris Samuel : > > > The rebalancing code does appear (from a naive read of the code) to be > > able to rebalance over stripes, but I have no idea if the disk format > > currently supports changing that on the fly. > > The rebalancing moves data/metadata to newly created chunks. If there > are two devices, the new chunks will be set up as RAID-1 by default. Very interesting! I didn't realise that - I was presuming that the=20 BTRFS_BLOCK_GROUP_RAID1 ioctl needed to be passed through (as at mkfs time)= to=20 change it into a RAID1 array. Could you point me at the code where this change is detected please ? Jus= t=20 so I can try and wrap my mind around it! > > Again it would appear that you need to have two partitions and that btr= fs > > cannot (at present) keep multiple data stripes on the same partition. > > Yes. I think this is due to performance reason. Understood. > Changing the code to support data duplication in single spindle configura= tion > is easy. OK, that's encouraging (though for my immediate purposes creating two=20 partitions is fine, but it might make life easier for others). Again thanks so much for the response! All the best, Chris =2D-=20 Chris Samuel : http://www.csamuel.org/ : Melbourne, VIC This email may come with a PGP signature as a file. Do not panic. =46or more info see: http://en.wikipedia.org/wiki/OpenPGP --nextPart1324315.X8rPFgaIUn Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iQEVAwUASVjIEY1yjaOTJg85AQJtbggAuaeiOn3s/0eMFINgKKNiK9tp7Y9K09kd B2rKH8Ep2AjmGDQssDOb128dZI16ZeMEx9oZaNcUwf9IbD+41V/NbMqoLRxUV7I0 RX3BQ5yZ7aDfKUMKa0UfJhOvDflBTa7ABnAaBqKoW1QSALGtGsDIRImKCJ4gVXD3 X2NqLvtHbj1XvlzKmDaZDj8XxVdkrwUq4VXgtFTchJ7tDceHFhpudvlWHmwtH/sX 09en4ydQFa+QB0E/l9bnOmwtda8uBmUFqK7LRjwqmhe42dY4cANWR70bdOhnFZLW V6HpTdaw/SXdNrYgIhNI5EATg432UnZGK3C9il0IHmwBbYs+x8ReFw== =0bfP -----END PGP SIGNATURE----- --nextPart1324315.X8rPFgaIUn--