Abstract: In a Distributed Virtual Array data storage system, data chunks making up data containers and identified by keys, which are independent of physical storage locations, are written in storage devices according to layouts specified in a layout data structure. When any of the storage devices becomes inaccessible, the chunks nominally designated to be written in the inaccessible storage devices are instead written to alternate devices. Information indicating writing to an alternate device may be included in or along with such chunks so as to make them easily identifiable during later reconstruction or re-writing to the intended storage device when it again becomes available.