Amazon EC2 and EBS disk space problem

Question

I am having a problem reconciling the space available on my EBS volume. According to the AWS console the volume is 50GB and is attached to an instance.

If I ssh to this instance and do a df -h, I get the following output:

Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1              15G   13G  3.0G  81% /
udev                  858M   76K  858M   1% /dev
none                  858M     0  858M   0% /dev/shm
none                  858M   72K  858M   1% /var/run
none                  858M     0  858M   0% /var/lock
none                  858M     0  858M   0% /lib/init/rw

I am pretty new to AWS. I interpret this as "there is a device attached and it has 15GB capacity. Whats more, you're nearly out of space!"

Can anyone point out the cause of the apparent discrepancy between the space advertised in the console and what is displayed on the instance?

Many thanks in advance

S

Answer 1

Yes, the issue is simple. The volume is only associated with the instance, but not mounted.

Check on the AWS console which drive it is mounted as - most likely /dev/sdf.

Then (on ubuntu):

sudo mkfs.ext3 /dev/sdf
sudo mkdir /ebs
sudo mount /dev/sdf /ebs

The first line formats the volume - using the ext3 file system type. This is pretty standard -- but depending on your usage (e.g. app server, database server, ...) you could also select another one like ext4 or xfs.

The second command creates a mount point and the third mounts it into it. This means that effectively, the new volume will be at /ebs. It should also show up in df now.

Last but not least, maybe also add an entry to /etc/fstab to make it reboot-proof.