1 TiB Amazon EBS volume can only be partly formatted.

a fix for EBS volumes showing and hanging as attaching

Today I ran into an issue where the an attached EBS volume could only be partly formatted. For a client setup I needed a 1 TiB volume. After creating the 1 TiB EBS volume I attached it to the EC2 instance running a RightScale CentOS 5.6 as /dev/sdb.

Without examining further I logged into the instance and formatted the newly attached disk.  After the format I mounted the disk in the system and did a standard df -h

# df -h

Which resulted in only a 400 GiB volume!?

Since I was unable to find out why I was only able to use 400 GiB for my drive I turned back to the AWS management console. Looking at the newly created volume I  found that the attachment status was still showing "attaching" which is odd because that should say attached like it normally does almost immediately.

Even force detaching and attaching, rebooting my instance, deleting the volume and recreating it was not getting me any results. I always found that the new volume was hanging in the "attaching" state after I attached it to /dev/sdb. 

As a last resort I tried creating a new volume but assigned it to /dev/sdc instead of /dev/sdb which I had been doing all the time and it immediately showed as "attached". That was sounding good. Next up was logging in to my instance and formatting this new volume. After formatting and mounting my newly created volume attached as /dev/sdc showed me the 1TiB I was expecting.


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