Formatting a USB Drive with ext4 for Use with Linux

Written by Taro Sato on March 27, 2009. Tagged: sysadmin Linux

I wish to use an external USB drive exclusively on a Linux system (in my case, Debian). I want to use the ext4 filesystem. Note that this method wipes out the filesystem on the drive.

Install hotplug-type package such that upon plugging the USB drive in the device is attached to somewhere in the system. I use KDE and it automatically prepares such an environment. When a USB drive is plugged in, I should see a message like this one in the system log:

$ sudo tail /var/log/messages
Dec 16 02:07:51 kernel: [ 3000.544361] scsi11 : usb-storage 3-2:1.0
...
Dec 16 02:07:56 mochi kernel: [ 3005.882879]  sdb: sdb1
...

or I may see something like this instead (I’m using USB 3.0 adapter now):

$ sudo tail -n 100 /var/log/messages | grep sd
...
May  3 12:38:33 mochi kernel: [   12.773057] sd 6:0:0:0: [sdb] Spinning up disk...
May  3 12:38:39 mochi kernel: [   18.782284] sd 6:0:0:0: [sdb] 3906963456 512-byte logical blocks: (2.00 TB/1.81 TiB)
May  3 12:38:39 mochi kernel: [   18.783052] sd 6:0:0:0: [sdb] Write Protect is off
May  3 12:38:39 mochi kernel: [   18.794337]  sdb: sdb1
May  3 12:38:39 mochi kernel: [   18.795569] sd 6:0:0:0: [sdb] Attached SCSI disk

Here, I find the device is at /dev/sdb and there is only one partition, /dev/sdb1, for example. I can also see all the disk devices as follows:

$ sudo fdisk -l

Disk /dev/sda: 80.0 GB, 80026361856 bytes
240 heads, 63 sectors/track, 10337 cylinders
Units = cylinders of 15120 * 512 = 7741440 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbd3cc0bb

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1       10338    78149633    5  Extended
/dev/sda5               1          46      340992   83  Linux
/dev/sda6              46          52       48128   83  Linux
/dev/sda7              52         698     4881408   83  Linux
/dev/sda8             698        1086     2928640   83  Linux
/dev/sda9            1086        1861     5858304   83  Linux
/dev/sda10           1861        2830     7323648   83  Linux
/dev/sda11           9305       10338     7812096   82  Linux swap / Solaris
/dev/sda12           2830        9304    48949248   83  Linux

Partition table entries are not in disk order

Disk /dev/sdb: 2000.4 GB, 2000365289472 bytes
255 heads, 63 sectors/track, 243197 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0005f107

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1      243198  1953480704    7  HPFS/NTFS

When the USB drive is new, the partition is most likely formatted in FAT or NTFS unless the drive is pre-formatted specifically for OS X. Now, prepare the partition for Linux:

$ sudo fdisk /dev/sdb

See help for detail by pressing m on the fdisk command shell. For example, press p to see the list of partitions in the disk. To create a new one press n (probably after deleting one or more partitions by pressing d). Finally press w to actually make changes to the drive. To use ext4 filesystem, do:

$ sudo mkfs.ext4 /dev/sdb1

after exiting fdisk.

If I always mount this drive on boot, add a line like this to /etc/fstab:

/dev/sdc1 /media/usbdrive ext4 defaults 0 0

assuming /media/usbdrive is the mount point. If I use KDE, adding an entry to /etc/fstab is no longer necessary; I can easily manage external drives with Device Notifier.

Update History

Feb 20, 2014 — Updated following a comment by Ugly Mug.

May 3, 2012 — Updated for my current system.

December 17, 2010 — Modified to use ext4 filesystem.