Patent ID: 7562251

Claim:
A volume server comprising: one or more processing units; and a storage medium storing program instructions executable by the one or more processing units to implement: virtualization functionality configured to aggregate storage within one or more block devices into a logical volume accessible to a volume client; and a layout table, wherein the layout table includes a plurality of entries, wherein each entry of the plurality of entries includes: an identification of an extent on a block device of the one or more block devices; and a virtual address range identifying blocks contained within a single corresponding stripe of the logical volume to which the extent is mapped; wherein a first virtual address range of a first entry of the plurality of entries overlaps with a second virtual address range of a second entry of the plurality of entries; and wherein an overlap of the first virtual address range and the second virtual address range is indicative of a mirroring of at least a portion of the first virtual address range; wherein the virtualization functionality is configured to access the layout table to obtain one or more block device addresses corresponding to a logical volume virtual address of a storage operation requested by the volume client; and wherein the virtualization functionality is further configured to disable access to the logical volume via the layout table if the number of valid non-error extents mapped to any block of the logical volume falls below a specified minimum value.