On 09/02/2010 06:56 AM, Tom Wizetek wrote: > Can someone please outline the process of removing a failed PV > (without replacing it) from a single VG / single LV? Let's say we just > want to continue using what's left of the LV and accept the data loss. You can activate the VG in partial mode, allowing you to access what's left of the data on the LVs. This lets you recover as much as remains on the surviving disks. E.g.: Set up some test devices & a test VG/LV: # pvcreate /dev/loop0 Physical volume "/dev/loop0" successfully created # pvcreate /dev/loop1 Physical volume "/dev/loop1" successfully created # vgcreate tvg1 /dev/loop0 /dev/loop1 Volume group "tvg1" successfully created # lvcreate -L 80M -n l0 tvg1 Logical volume "l0" created # lvs tvg1 LV VG Attr LSize Origin Snap% Move Log Copy% Convert l0 tvg1 -wi-a- 80.00M De-activate the VG and "hide" a PV: # vgchange -an tvg1 0 logical volume(s) in volume group "tvg1" now active # losetup -d /dev/loop1 Try to re-activate: # vgchange -ay tvg1 Couldn't find device with uuid 'YU47yZ-CWBj-dANw-kc4Y-gLEt-KcqK-yWXWEn'. Couldn't find device with uuid 'YU47yZ-CWBj-dANw-kc4Y-gLEt-KcqK-yWXWEn'. Refusing activation of partial LV l0. Use --partial to override. 0 logical volume(s) in volume group "tvg1" now active Add the partial flag: # vgchange -ay --partial tvg1 Partial mode. Incomplete volume groups will be activated read-only. Couldn't find device with uuid 'YU47yZ-CWBj-dANw-kc4Y-gLEt-KcqK-yWXWEn'. Couldn't find device with uuid 'YU47yZ-CWBj-dANw-kc4Y-gLEt-KcqK-yWXWEn'. 1 logical volume(s) in volume group "tvg1" now active Now we can get at what's left: # dd if=/dev/tvg1/l0 of=/dev/null dd: reading `/dev/tvg1/l0': Input/output error 122880+0 records in 122880+0 records out 62914560 bytes (63 MB) copied, 1.04186 s, 60.4 MB/s To see what's happened here we can look at the device-mapper tables for the device: # dmsetup table tvg1-l0 0 122880 linear 7:0 384 # this is the surviving PV 122880 40960 linear 253:7 0 # this is the missing PV The device 253:7 is device dm-7 which has been created by the vgchange --partial to fill in the missing space: # dmsetup table tvg1-l0-missing_1_0 0 40960 error The error target is a special target that just returns I/O errors - you can't (obviously) read the data that is not there but you can still attempt to recover whatever's left on the surviving disks. Older versions of the tools needed you to set up the "missing stripe filler" device manually but since about 2.02.40 this is automatic. It's a bit dated now but you might also find some of this presentation from a couple of years back helpful: http://people.redhat.com/breeves/talks/iotc-2008-recovering-lvm2/index.html Regards, Bryn. _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
