Chapter 30. Getting started with an ext4 file system

Procedure

1. To create an ext4 file system:

   • For a regular-partition device, an LVM volume, an MD volume, or a similar device, use the following command:

     # mkfs.ext4 /dev/block_device

     Replace /dev/block_device with the path to a block device.

     For example, /dev/sdb1, /dev/disk/by-uuid/05e99ec8-def1-4a5e-8a9d-5945339ceb2a, or /dev/my-volgroup/my-lv. In general, the default options are optimal for most usage scenarios.

   • For striped block devices (for example, RAID5 arrays), the stripe geometry can be specified at the time of file system creation. Using proper stripe geometry enhances the performance of an ext4 file system. For example, to create a file system with a 64k stride (that is, 16 x 4096) on a 4k-block file system, use the following command:

     # mkfs.ext4 -E stride=16,stripe-width=64 /dev/block_device

     In the given example:

     • stride=value: Specifies the RAID chunk size
     • stripe-width=value: Specifies the number of data disks in a RAID device, or the number of stripe units in the stripe.
   Note

   • To specify a UUID when creating a file system:

     # mkfs.ext4 -U UUID /dev/block_device

     Replace UUID with the UUID you want to set: for example, 7cd65de3-e0be-41d9-b66d-96d749c02da7.

     Replace /dev/block_device with the path to an ext4 file system to have the UUID added to it: for example, /dev/sda8.

   • To specify a label when creating a file system:

     # mkfs.ext4 -L label-name /dev/block_device

2. To view the created ext4 file system:

   # blkid

Procedure

1. To create a mount point to mount the file system:

   # mkdir /mount/point

   Replace /mount/point with the directory name where mount point of the partition must be created.

2. To mount an ext4 file system:

   • To mount an ext4 file system with no extra options:

     # mount /dev/block_device /mount/point

   • To mount the file system persistently, see Persistently mounting file systems.

3. To view the mounted file system:

   # df -h

Procedure

1. To resize an ext4 file system, take the following steps:

   • To shrink and grow the size of an unmounted ext4 file system:

     # umount /dev/block_device
     # e2fsck -f /dev/block_device
     # resize2fs /dev/block_device size

     Replace /dev/block_device with the path to the block device, for example /dev/sdb1.

     Replace size with the required resize value using s, K, M, G, and T suffixes.

   • An ext4 file system may be grown while mounted using the resize2fs command:

     # resize2fs /mount/device size

     Note

     The size parameter is optional (and often redundant) when expanding. The resize2fs automatically expands to fill the available space of the container, usually a logical volume or partition.

2. To view the resized file system:

   # df -h