Abstract: Maintaining a set of extents corresponding to a portion of an initial logical volume that is to be copied includes initializing a table having entries corresponding to different portions of the initial logical volume, where each of the entries is initialized with a first value, following initializing the table, providing a second value different from the first value to an entry in the table corresponding to a portion of the initial logical volume to which a write operation is performed and establishing the set of extents, where the first value is provided to entries in the table that correspond to portions of the initial logical device indicated by the extents. Data of the initial logical volume corresponding to the set of extents may be copied to at least one other logical volume.

Abstract: Providing snapshots for a logical device includes maintaining a global sequence number for the logical device, providing a snapshot table having a plurality of entries, where each of the entries corresponds to a targetless snapshot and includes a sequence number associated with a particular one of the targetless snapshots, the sequence number corresponding to the global sequence number at a time each of the snapshots is created, and, if a sequence number associated with a specific portion of the logical device is less than the global sequence number, then prior to moving new data to a specific portion of the logical device, copying old data from the specific portion to a location in a pool device, setting a pointer in a replication data pointer table to point to the location in the pool device and setting the sequence number associated with the specific portion to equal the global sequence number.

Abstract: Maintaining a set of extents corresponding to a portion of an initial logical volume that is to be copied includes initializing a table having entries corresponding to different portions of the initial logical volume, where each of the entries is initialized with a first value, following initializing the table, providing a second value different from the first value to an entry in the table corresponding to a portion of the initial logical volume to which a write operation is performed and establishing the set of extents, where the first value is provided to entries in the table that correspond to portions of the initial logical device indicated by the extents. Data of the initial logical volume corresponding to the set of extents may be copied to at least one other logical volume.