From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from frost.carfax.org.uk ([85.119.82.111]:55401 "EHLO frost.carfax.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758279Ab3FMVVE (ORCPT ); Thu, 13 Jun 2013 17:21:04 -0400 Date: Thu, 13 Jun 2013 22:21:00 +0100 From: Hugo Mills To: Hendrik Friedel Cc: linux-btrfs Subject: Re: raid0, raid1, raid5, what to choose? Message-ID: <20130613212100.GG11290@carfax.org.uk> References: <51BA34EC.1080800@friedels.name> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="5UGlQXeG3ziZS81+" In-Reply-To: <51BA34EC.1080800@friedels.name> Sender: linux-btrfs-owner@vger.kernel.org List-ID: --5UGlQXeG3ziZS81+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Jun 13, 2013 at 11:09:00PM +0200, Hendrik Friedel wrote: > Hello, > > I'd appreciate your recommendation on this: > > I have three hdd with 3TB each. I intend to use them as raid5 eventually. > currently I use them like this: > > # mount|grep sd > /dev/sda1 on /mnt/Datenplatte type ext4 > /dev/sdb1 on /mnt/BTRFS/Video type btrfs > /dev/sdb1 on /mnt/BTRFS/rsnapshot type btrfs > > #df -h > /dev/sda1 2,7T 1,3T 1,3T 51% /mnt/Datenplatte > /dev/sdb1 5,5T 5,4T 93G 99% /mnt/BTRFS/Video > /dev/sdb1 5,5T 5,4T 93G 99% /mnt/BTRFS/rsnapshot > > Now, what surprises me, and here I lack memory- is that sdb appears > twice.. I think, I created a raid1, but how can I find out? Appearing twice in that list is more an indication that you have multiple subvolumes -- check the subvol= options in /etc/fstab > #/usr/local/smarthome# ~/btrfs/btrfs-progs/btrfs fi show /dev/sdb1 > Label: none uuid: 989306aa-d291-4752-8477-0baf94f8c42f > Total devices 2 FS bytes used 2.68TB > devid 2 size 2.73TB used 2.73TB path /dev/sdc1 > devid 1 size 2.73TB used 2.73TB path /dev/sdb1 > > Now, I wanted to convert it to raid0, because I lack space and > redundancy is not important for the Videos and the Backup, but this > fails: > ~/btrfs/btrfs-progs/btrfs fi balance start -dconvert=raid0 /mnt/BTRFS/ > ERROR: error during balancing '/mnt/BTRFS/' - Inappropriate ioctl for device /mnt/BTRFS isn't a btrfs subvol, according to what you have listed above. It's a subdirectory in /mnt which is contains two subdirs (Video and rsnapshot) which are used as mountpoints for subvolumes. Try running the above command with /mnt/BTRFS/Video instead (or rsnapshot -- it doesn't matter which). > dmesg does not help here. > > Anyway: This gave me some time to think about this. In fact, as soon > as raid5 is stable, I want to have all three as a raid5. Will this > be possible with a balance command? If so: will this be possible as > soon as raid5 is stable, or will I have to wait longer? Yes, it's possible to convert to RAID-5 right now -- although the code's not settled down into its final form quite yet. Note that RAID-5 over two devices won't give you any space benefits over RAID-1 over two devices. (Or any reliability benefits either). Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- "Are you the man who rules the Universe?" "Well, I --- try not to." --5UGlQXeG3ziZS81+ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIVAwUBUbo3vFheFHXiqx3kAQIlUQ//doXYOqj+PbgcEH7YExE5tNKuS3K0y4p8 n9iXwrc7XGwZxpp48z2kw1RkpjpiVA+LV75SlnMK7pu91c5EJX4w3gHSTlUh17np ZKFLLrQvICh/5RNOOdllSeqwgG4zdo6M+BRrwhTzJ/2XUlRK1N4AdVO+H88sWNiD TSQ+2cr5+jHdeJy0CYFCm2RSCh+da5t4qTPNiiCPJgmu6kTA4R2rT/wglXAEv0rq UtcK02R02j9WSX+2J3axaEx/CY+KatJjFYDJDLUUVGBqor/i291q4yi4OAe4EJOZ VWnjtEXXqV9iY5hMW3wLgg7fUcDHJWE6p8cG6TjL+320LzKOrEr+GFvU/xX4ju5R jAeVOa0gem+Nz73PaiUHFiTIN2fDOAXP97ogUnbP9p355iYEIaXVzvS4cuZux0Pk h82MxSeXCB/WGaeFuMBBHRY5I2gmrH4pen4r2BNKXk8azpVsFXsIVIOHt/C5u9JD EU8ABLDGc1Khl/vRmiftUmr+owJ5HOUVcd+eF4USODFuQj5vPLoMRmznLIvndaE2 RNy3RTvBe6sfqJLToC5mRjj8pHJAOKiUW/8J8O0vwJPASKUOHYitDbWR5zRG2r3o Q7UhQCsbmwq5TEioTBz0920Ikh1brwJkR2C6RLk7i6GMoj7kI7R0d5+teSH6ejch W8JMHLUvcYg= =l3o7 -----END PGP SIGNATURE----- --5UGlQXeG3ziZS81+--