[linux-lvm] Recovering from a disk failure

[Thien Vu]

Hi all,

I was preparing to move data residing on a LV to a RAID5 array when the
cruel hand of irony slapped me, and one of the drives in my LV died. I have
not migrated any data off of the LV.

Here is my setup:
* Linear lvm: 80GB, 80GB, 40GB ( I think in this order also, but I"m not
100percent sure
* The 40GB died: doesn't power on, isn't detected by BIOS.

I've searched the archives, and there seems to be 2 solutions:
* Bottom up solution- get a replacement drive, do pvcreate, restore the vg
data onto the drive, run vgscan and hope

I tried this, but I can't find the UUID for the missing drive (because I
can't read off of it) so there's no way for me to assign the replacement
drive the correct UUID. I've tried using vgcfgbackup/restore (from LVM2
with -P flag) but it doesn't record the UUID for the missing drive.

* Top down solution -get device-mapper and LVM2, vgscan, vgchange -ay -P,
mount the filesystem and hope

I tried this, but the filesystem on the LV is reiserfs and it won't allow me
to mount the LV. I would try reiserfsck and other tools, but the VG is
incomplete and is only accessible read-only.

Below is the output of vgdisplay -v -P (from LVM2):

Thanks for any assistance,

Thien

-------------------------
  Partial mode. Incomplete volume groups will be activated read-only.
    Finding all volume groups
    Finding volume group "vg_home"
  2 PV(s) found for VG vg_home: expected 3
  Logical volume (lv_home) contains an incomplete mapping table.
  --- Volume group ---
  VG Name               vg_home
  System ID             lisa1026448546
  Format                lvm1
  VG Access             read
  VG Status             resizable
  MAX LV                256
  Cur LV                1
  Open LV               0
  Max PV                256
  Cur PV                2
  Act PV                2
  VG Size               188.12 GB
  PE Size               4.00 MB
  Total PE              48160
  Alloc PE / Size       48160 / 188.12 GB
  Free  PE / Size       0 / 0
  VG UUID               BHXFw1-6juI-h8jW-fxBQ-H7EW-ng14-6iGQX2

  --- Logical volume ---
  LV Name                /dev/vg_home/lv_home
  VG Name                vg_home
  LV UUID                000000-0000-0000-0000-0000-0000-000000
  LV Write Access        read/write
  LV Status              NOT available
  LV Size                188.12 GB
  Current LE             48160
  Segments               9544
  Allocation             next free
  Read ahead sectors     1024

  --- Physical volumes ---
  PV Name               /dev/discs/disc1/disc
  PV UUID               OUcSLF-p0XM-5Qhc-qViC-hhZG-ALcl-pkdc00
  PV Status             allocatable
  Total PE / Free PE    19540 / 0

  PV Name               /dev/discs/disc2/disc
  PV UUID               24IIKM-aegb-RuxL-27ro-AMLZ-bU9K-XFsHGS
  PV Status             allocatable
  Total PE / Free PE    19078 / 0