I'm using dm-crypt based transparent disk encryption subsystem in Linux. The cryptsetup command is used deal with the Linux Unified Key Setup (LUKS) on-disk format and mount the partition. My setup includes RAID-10 with an LVM physical volume. How do I run fsck ("file system check") on dm-crypt / LUKS based LVM physical volume under Linux operating systems?
First, you need to open the LUKS partition device and sets up a mapping using cryptsetup command. Do not run fsck command on mounted partition. Type the following command as root user:
# cryptsetup luksOpen /dev/md3 securebackup
Sample outputs:
Enter passphrase for /dev/md3:
Where,
- /dev/md3 - My raid device. The device name will change according to your setup.
- securebackup - Sets up a mapping to securebackup after successful verification. This name will change according to your setup.
To read all physical volumes, enter:
# vgscan --mknodes
Sample outputs:
Reading all physical volumes. This may take a while... Found volume group "cryptvg" using metadata type lvm2
Where,
- cryptvg - Group volume name. It was created using lvm2 setup. This name will change according to your setup.
To activate logical volume and to create /dev/cryptvg/DEVICE name, enter:
# vgchange -ay
Sample outputs:
1 logical volume(s) in volume group "cryptvg" now active
You can see your device name at the following location
# ls -l /dev/cryptvg
# ls -l /dev/mapper/
Sample outputs:
total 0 crw------- 1 root root 10, 59 Dec 6 12:27 control lrwxrwxrwx 1 root root 7 Dec 6 12:54 cryptvg-mybackup -> ../dm-1 lrwxrwxrwx 1 root root 7 Dec 6 12:50 securebackup -> ../dm-0
You can type the following command to see information about VG in use:
# vgdisplay
Sample outputs:
--- Volume group --- VG Name cryptvg System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 2 VG Access read/write VG Status resizable MAX LV 0 Cur LV 1 Open LV 0 Max PV 0 Cur PV 1 Act PV 1 VG Size 600.01 GiB PE Size 4.00 MiB Total PE 153602 Alloc PE / Size 153602 / 600.01 GiB Free PE / Size 0 / 0 VG UUID W0IDJ0-Yjt9-093X-qAzH-tbCJ-9NYH-BV1RYd
To display attributes of a physical volume, enter:
# pvdisplay
Sample outputs:
--- Physical volume --- PV Name /dev/dm-0 VG Name cryptvg PV Size 600.01 GiB / not usable 2.50 MiB Allocatable yes (but full) PE Size 4.00 MiB Total PE 153602 Free PE 0 Allocated PE 153602 PV UUID swS5Nw-suTe-N0io-72LY-CBG5-6FhU-Tq8kYZ
OR
# pvdisplay /dev/dm-0
Sample outputs:
--- Physical volume --- PV Name /dev/dm-0 VG Name cryptvg PV Size 600.01 GiB / not usable 2.50 MiB Allocatable yes (but full) PE Size 4.00 MiB Total PE 153602 Free PE 0 Allocated PE 153602 PV UUID swS5Nw-suTe-N0io-72LY-CBG5-6FhU-Tq8kYZ
To display attributes of a logical volume, enter:
# lvdisplay
Sample outputs:
--- Logical volume ---
LV Name /dev/cryptvg/mybackup
VG Name cryptvg
LV UUID g0AghZ-bcv5-n6pP-AQUA-5c32-fQa1-OteSlg
LV Write Access read/write
LV Status available
# open 0
LV Size 600.01 GiB
Current LE 153602
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 6144
Block device 253:1
To check and possibly repair a LVM2+LUKS based Linux file system, enter:
# fsck -C -V /dev/cryptvg/mybackup
OR
# fsck -C -V -y /dev/cryptvg/mybackup
Sample outputs:
Fig.01: Running fsck on an LVM2 (LUKS based) volume
It may take some time to complete the fsck:
fsck from util-linux-ng 2.17.2 [/sbin/fsck.ext3 (1) -- /dev/mapper/cryptvg-mybackup] fsck.ext3 -C0 /dev/mapper/cryptvg-mybackup e2fsck 1.41.12 (17-May-2010) /dev/mapper/cryptvg-mybackup has been mounted 63 times without being checked, check forced. Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/mapper/cryptvg-mybackup: 483163/39329792 files (0.2% non-contiguous), 16626195/157288448 blocks
You can now mount your device using the mount command:
# mount /dev/cryptvg/mybackup /securebackup/
# df -H
Sample outputs:
Filesystem Size Used Avail Use% Mounted on
/dev/md0 127G 930M 120G 1% /
tmpfs 1.1G 0 1.1G 0% /lib/init/rw
udev 1.1G 267k 1.1G 1% /dev
tmpfs 1.1G 0 1.1G 0% /dev/shm
/dev/md2 1.6T 88G 1.5T 6% /data
/dev/mapper/cryptvg-mybackup
635G 58G 544G 10% /securebackup
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