Nova-volume provides persistent block storage compatible with Amazon's Elastic Block Store. The storage on the instances is non persistent in nature and hence any data that you generate and store on the file system on the first disk of the instance gets lost when the instance is terminated. You will need to use persistent volumes provided by nova-volume if you want any data generated during the life of the instance to persist after the instance is terminated.
Commands from euca2ools package can be used to manage these volumes.
Here are a few examples:
