Having LVM mounting issues?

[dedanna1029]

Was having some issues getting an LVM to mount; need to back up the Fedora drive and do a clean installation on it. I'm in Arch. Got talking with Joste today on I.M., and we tried everything here to no avail (well, we could see the /home partition (which is what needed backing up), but it still wouldn't mount):

Code: Select all

# mount /dev/sdb2 /mnt/test
mount: unknown filesystem type 'LVM2_member'

Went to the steps on that link:

Code: Select all

# pvs
  PV         VG         Fmt  Attr PSize   PFree
  /dev/sdb2  vg_dedanna lvm2 a-   189.41g    0

Code: Select all

# lvdisplay /dev/vg_dedanna
  /proc/misc: No entry for device-mapper found
  Is device-mapper driver missing from kernel?
  Failure to communicate with kernel device-mapper driver.
  --- Logical volume ---
  LV Name                /dev/vg_dedanna/lv_root
  VG Name                vg_dedanna
  LV UUID                0mN639-Xj12-Lhuh-u899-SXcW-xPGX-WmSN4I
  LV Write Access        read/write
  LV Status              NOT available
  LV Size                32.00 GiB
  Current LE             1024
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
   
  --- Logical volume ---
  LV Name                /dev/vg_dedanna/lv_swap
  VG Name                vg_dedanna
  LV UUID                PehJnJ-cWFo-h3Sc-eyqG-LLs2-X96I-TiG36P
  LV Write Access        read/write
  LV Status              NOT available
  LV Size                1.00 GiB
  Current LE             32
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
   
  --- Logical volume ---
  LV Name                /dev/vg_dedanna/lv_home
  VG Name                vg_dedanna
  LV UUID                g4xuE8-Lf9j-JkU4-eOmM-ZqWc-DNyq-FjP2U1
  LV Write Access        read/write
  LV Status              NOT available
  LV Size                156.41 GiB
  Current LE             5005
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto

... Which proved conclusively that the drive was "there" to mount. But still...

Code: Select all

# mount /dev/vg_dedanna/lv_home /mnt/test
mount: special device /dev/vg_dedanna/lv_home does not exist

... Which we knew good and well, it did.

Tried lvchange:

Code: Select all

# lvchange -a y /dev/vg_dedanna/lv_home
  /proc/misc: No entry for device-mapper found
  Is device-mapper driver missing from kernel?
  Failure to communicate with kernel device-mapper driver.

At this point, Joste pops off with:

modprobe dm-mod
Should fix it.

Turns out he is a god:

Code: Select all

[root@dedanna ~]# modprobe dm-mod
[root@dedanna ~]# lvchange -a y /dev/vg_dedanna/lv_home
[root@dedanna ~]# mount /dev/vg_dedanna/lv_home /mnt/test

I'm happily backing up the 33 Gbs I had used on that drive now...

Must remember modprobe dm-mod... thank you Joste. Mwah.

I seriously wish Fedora would knock it off with the LVM crap.