US Patent 10372329 Managing storage devices in a distributed storage system

Storage systems store data in a storage pool comprising storage devices or virtual devices. The storage pool may be allocated for a particular purpose. If a virtual device within the storage pool needs to be repurposed, the virtual device is removed from the storage pool. Data is moved from the removed virtual device to one or more target virtual devices. Segments of the source virtual device being removed are copied to target virtual devices. Mapping tables associating source segments with target segments are stored. If the storage system receives a request to access data stored on a virtual device that is removed, the storage system processes the mapping tables to determine where the data is stored.