Storage system and methods of mapping addresses of snapshot families

A storage system comprising a plurality of physical storage devices controlled by a plurality of storage control devices constituting a storage control layer operatively coupled to a plurality of hosts and to the plurality of physical storage devices constituting a physical storage space, said control layer configured to manage a plurality of snapshot families, each snapshot family (SF) is constituted by SF members comprising a master logical volume and a plurality of snapshots corresponding thereto and is characterized by a SF logical address space associated with the SF, wherein the control layer comprises:

• means for generating, for each given SF among the plurality of snapshot families, a corresponding first SF mapping data structure comprising one or more entries,
• wherein each entry is associated with a variable range of contiguous logical addresses within the SF logical address space and is characterized by a value that is indicative of a length of the range and its offset in the SF logical address space, and
• wherein each entry in the first SF mapping data structure is further associated with a second SF data structure configured to provide mapping between the range of contiguous logical addresses associated with the entry into one or more physical address ranges, respectively correlated to the SF members;
• means for identifying an addressed snapshot family and an addressed member therein upon receiving an access request specifying an addressed LUN (Logical Unit Number) and LBA (Logical Block Address) range;
• means for searching a first SF mapping data structure associated with the identified addresses SF for entry associated with a range of contiguous logical addresses corresponding to LBA range specified in the access request;
• and
• means for searching a respective second SF mapping data structure associated with the entry found in the first SF mapping data structure for identifying physical addresses corresponding to the requested LBA range in the addressed member of the addressed snapshot family.

A method comprising:

• by a storage system capable to maintain a snapshot family comprising a plurality of members having hierarchical relations therebetween:
• generating a mapping data structure comprising a plurality of mapping entries providing mapping for respective logical address ranges within a logical address space assigned to the snapshot family;
• configuring a mapping entry of the plurality of mapping entries to comprise one or more mappings for mapping a logical address range associated with the mapping entry into one or more physical address ranges, respectively correlated to one or more representative members of the snapshot family;
• omitting from the mapping entry a certain mapping corresponding to an omitted member comprised in the snapshot family and different from any of the one or more representative members sharing a respective range of physical addresses;
• and
• responsive to an access request directed to the logical address range and the omitted member, determining a representative member from the one or more representative members, the determining being provided using a predefined rule related to the hierarchical and sequential relations between members of the snapshot family;
• and responding to the access request by using a physical address range correlated to the representative member.