Volume workers are used for the management of LVM-based instance volumes. Volume Workers perform volume related functions such as creation, deletion, attaching a volume to an instance, and detaching a volume from an instance. Volumes provide a way of providing persistent storage for use by instances, as the main disk attached to an instance is non-persistent and any changes made to it are lost when the volume is detached or the instance is terminated. When a volume is detached from an instance or when an instance, to which the volume is attached, is terminated, it retains the data that was stored on it when it was attached to an instance earlier. This data can be accessed by reattaching the volume to the same instance or by attaching it to another instances.
Any valuable data that gets accumulated during the life cycle of an instance should be written to a volume, so that it can be accessed later. This typically applies to the storage needs of database servers etc.
