Thomas Schneider
2013-Oct-13 13:02 UTC
BTRFS Multidevice Filesystem: Save to delete one device?
Hello! I have the following disk setup: 1x 3TB WD 2x 2TB WD On each disk I have created a single partition, and this partition is formatted in BTRFS. Then, I have setup a multidevice filesystem: root@pc5:/media# btrfs filesystem show Label: ''WD30EZRX-00M'' uuid: 7008c941-a5e1-44b6-9965-de726d22cc21 Total devices 3 FS bytes used 4.07TB devid 2 size 1.82TB used 1.72TB path /dev/sdd1 devid 1 size 2.73TB used 2.63TB path /dev/sdb1 devid 3 size 1.82TB used 0.00 path /dev/sdc1 Btrfs Btrfs v0.19 root@pc5:/media# btrfs filesystem df /media/sdb1/ Data: total=4.17TB, used=4.07TB System, DUP: total=8.00MB, used=472.00KB System: total=4.00MB, used=0.00 Metadata, DUP: total=94.00GB, used=5.30GB Metadata: total=8.00MB, used=0.00 You can see that devid 3 (=/dev/sdc1) is not utilized at all. Question: How can I delete devid 2 (=/dev/sdd1) securely without loosing any data? Please note that all data stored in this multidevice filesystem is located in a subvolume, means no data is stored in root tree. root@pc5:/media# btrfs subvolume list /media/sdb1/ ID 258 top level 5 path @video ID 2760 top level 5 path @musik ID 3995 top level 5 path @bilder ID 3996 top level 5 path @dokumente ID 3997 top level 5 path @software ID 3998 top level 5 path @hardware -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hugo Mills
2013-Oct-13 13:14 UTC
Re: BTRFS Multidevice Filesystem: Save to delete one device?
On Sun, Oct 13, 2013 at 03:02:40PM +0200, Thomas Schneider wrote:> Hello! > I have the following disk setup: > 1x 3TB WD > 2x 2TB WD > On each disk I have created a single partition, and this partition is formatted in BTRFS. > Then, I have setup a multidevice filesystem: > root@pc5:/media# btrfs filesystem show > Label: ''WD30EZRX-00M'' uuid: 7008c941-a5e1-44b6-9965-de726d22cc21 > Total devices 3 FS bytes used 4.07TB > devid 2 size 1.82TB used 1.72TB path /dev/sdd1 > devid 1 size 2.73TB used 2.63TB path /dev/sdb1 > devid 3 size 1.82TB used 0.00 path /dev/sdc1 > > Btrfs Btrfs v0.19 > root@pc5:/media# btrfs filesystem df /media/sdb1/ > Data: total=4.17TB, used=4.07TB > System, DUP: total=8.00MB, used=472.00KB > System: total=4.00MB, used=0.00 > Metadata, DUP: total=94.00GB, used=5.30GB > Metadata: total=8.00MB, used=0.00 > > You can see that devid 3 (=/dev/sdc1) is not utilized at all.Was that added later, after you''d filled much of the FS? (I''m just checking -- otherwise, the space usage you show here might indicate some kind of problem).> Question: > How can I delete devid 2 (=/dev/sdd1) securely without loosing any data?$ btrfs dev del /media/sdb1 /dev/sdd1 The data on the device will be moved elsewhere in the FS (i.e. to the other two devices). However, be aware that there''s a bug in the code in the area of balancing and device management, and you should probably be running a 3.12-rc4+ kernel (or 3.11.5) before you try this. Your userspace tools are also old and could probably do with an upgrade -- but that''s not particulary an issue in this instance.> Please note that all data stored in this multidevice filesystem is located in a subvolume, means no data is stored in root tree. > > root@pc5:/media# btrfs subvolume list /media/sdb1/ > ID 258 top level 5 path @video > ID 2760 top level 5 path @musik > ID 3995 top level 5 path @bilder > ID 3996 top level 5 path @dokumente > ID 3997 top level 5 path @software > ID 3998 top level 5 path @hardwareThat doesn''t make any difference for this operation. 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 --- "You know, the British have always been nice to mad people." ---