linux-raw-filesystem-management


linux-raw-filesystem-management

Linux Raw File system Management
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Pretend we have added a new disk to our computer.

The operating system has detected this new disk as device /dev/xvdf.

The following documents the steps we need to take to use this new space.

Partition the device

You may cut the device into separate logical disks.

In my case I want to use the whole disk

.. code-block:: bash

sudo fdisk /dev/xvdf # choose needed settings

Format the partition with a filesystem

We want to use ext4 so we do

.. code-block:: bash

sudo mkfs.ext4 /dev/xvdf

mke2fs 1.42 (29-Nov-2011) Filesystem label= OS type: Linux Block
size=4096 (log=2) Fragment size=4096 (log=2) Stride=0 blocks, Stripe
width=0 blocks 6553600 inodes, 26214400 blocks 1310720 blocks (5.00%)
reserved for the super user First data block=0 Maximum filesystem
blocks=4294967296 800 block groups 32768 blocks per group, 32768
fragments per group 8192 inodes per group Superblock backups stored on
blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632,
2654208, 4096000, 7962624, 11239424, 20480000, 23887872

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done Writing superblocks and filesystem
accounting information: done

Mount and test the new filesystem

.. code-block:: bash

sudo mount /dev/xvdf1 /mnt touch /mnt/testfile ls /mnt sudo umount /mnt
ls /mnt sudo mount /dev/xvdf1 /mnt

Automatically mount partition at system boot

Add an entry into /etc/fstab for new partition.

.. code-block:: text

/dev/xvdf1 /mnt ext4 defaults 0 0

Remount read-only or read-write

Sometimes live disks and rescue modes mount your partitions for you. In
my case the rescue was mounting root partition as read-only, and I
needed to remove an entry in /etc/fstab. This command will remount a
partition with rw:

.. code-block:: bash

mount -o remount,rw /dev/mapper/VolGroup00-LogVol0 /

This allowed me to edit /etc/fstab, remove the bad entry and reboot. The
server came back online. We still need to figure out what happened to
the disk, try to recover it.