External hard disk drive reduced to 32GB

We recently had a customer call us to complain that their new 320GB USB external drive was only showing a capacity of 32GB. They had tried to use it to create a “system recovery drive” which is to be commended. This drive can be used to start up a computer that has suffered a failure of the Operating System.
After creating the recovery drive, they realised that they had a smaller USB drive in a drawer which they wanted to use.
It was then that they discovered that their 320GB drive had “shrunk” in size to 32GB.
The reason for this is that in creating the recovery drive, Windows erases the drive and creates a 32GB partition; leaving the remaining space as “unallocated”.
By going into the “disk management” utility, we were able to extend the 32GB partition back up to the 320GB. After formatting this partition, the original capacity of 320GB was restored!