Useful Commands when Fixing EBS in EC2

When there is problem with your EBS Volume, you can try detach the root device, attaching it to another device and access it to fix it.

To attach: mount /dev/xvdf /vol
To detach: umount /vol
where /vol is the mount point

When you want to re-attach a root device, you have to set the device name to
/sda1 instead of the default name /sdf

If error when trying to mount EBS:

mount: wrong fs type, bad option, bad superblock on /dev/xvdf,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so

sudo mount /dev/xvdf /vol -t ext4 or sudo mount /dev/xvdf1 /vol -t ext4

Filesystem check: fsck

If any settings wrong, it’s in /etc/fstab