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FSCK

STILL BEING WORKED ON!!!!

  1.  Running a fsck check without repair

If filesystem corruption hasn't yet been confirmed, we first want to run a read only check of the filesystem.

We first need to identify the device to check:

root@test:~# df
Filesystem                        1K-blocks    Used Available Use% Mounted on
tmpfs                                400556    1068    399488   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv  15371208 7497096   7071504  52% /
tmpfs                               2002776       0   2002776   0% /dev/shm
tmpfs                                  5120       0      5120   0% /run/lock
/dev/sda2                           1992552  256828   1614484  14% /boot
tmpfs                                400552       4    400548   1% /run/user/0

In this case, I'm wanting to run a check for '/dev/mapper/ubuntu--vg-ubuntu--lv' which is mounted to /

A. Boot the server into 'single user mode'

B. Once in single user mode, we can look to initiate the fsck

We will first need to check the filesystem type being used:

get the device name:

root@test:~# df
Filesystem                        1K-blocks    Used Available Use% Mounted on
tmpfs                                400556    1068    399488   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv  15371208 7497096   7071504  52% /
tmpfs                               2002776       0   2002776   0% /dev/shm
tmpfs                                  5120       0      5120   0% /run/lock
/dev/sda2                           1992552  256828   1614484  14% /boot
tmpfs                                400552       4    400548   1% /run/user/0

In this example, we want to check '/dev/mapper/ubuntu--vg-ubuntu--lv' which is mounted to /.

Check the filesystem type:

root@test:~# blkid /dev/mapper/ubuntu--vg-ubuntu--lv
/dev/mapper/ubuntu--vg-ubuntu--lv: UUID="2f1c5c3e-54e0-4edc-9d19-a1f170959479" BLOCK_SIZE="4096" TYPE="ext4"

As you can see, in this example the type is ext4.

C. Running the fsck:

The general command structure for running an fsck is as below:

##Check for errors (No repair)
fsck.filesystem_type /dev/device_name -o ro

##Check and repair errors
fsck.filesystem_type /dev/device_name

In this example, I'm going to run a check and then a repair seperately:

##Check for errors (No repair)
fsck.ext4 /dev/mapper/ubuntu--vg-ubuntu--lv -o ro

##Check and repair errors
fsck.ext4 /dev/mapper/ubuntu--vg-ubuntu--lv

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