Capacity-expansion of a logical volume

A controller of a logical volume, comprising:

• a memory to store a global metadata unit and a plurality of local metadata units, where:
• the global metadata unit includes a description of the logical volume, a list of the plurality of local metadata units, and ranges of logical blocks of the logical volume corresponding to the plurality of local metadata units;
• and
• each of the plurality of local metadata units includes a description of a local RAID set and a range of logical blocks on the local RAID set;
• a processor, coupled to the memory, to create a new local metadata unit having a description of a new local RAID set and a range of logical blocks on the new drive, and to add the new local metadata unit to the global metadata unit to expand the logical volume to incorporate the new local RAID set;
• and
• wherein the new local RAID set includes a new disk and at least a disk from a previous RAID set, and wherein the new local RAID set adds capacity to a previously established and utilized logical volume, and creating a second new local metadata unit having a description of a second new local RAID set, wherein the second new local RAID set is created, wherein the second new local RAID set includes the new disk and only a second disk from the previous RAID set.

A storage system, comprising:

• a plurality of physical drives forming a plurality of local RAID sets;
• a controller to control the plurality of local RAID sets as a logical volume, the controller storing a global metadata unit and a local metadata unit, where:
• the global metadata unit includes a description of the logical volume, a list of the plurality of local metadata units, and ranges of logical blocks of the logical volume corresponding to the plurality of local metadata units;
• and
• each of the plurality of local metadata units includes a description of a respective one of the local RAID sets and a range of logical blocks on the respective one of the local RAID sets;
• wherein the controller adds a new local RAID set to the RAID volume by creating a new local metadata unit having a description of the new local RAID set to be added to the RAID volume and a range of logical blocks on the new local RAID set, and adding the new local metadata unit to the global metadata unit to expand the logical volume to incorporate the new local RAID set;
• and
• wherein the new local RAID set includes a new disk and at least a disk from a previous RAID set, and wherein the new local RAID set adds capacity to a previously established and utilized logical volume, and creating a second new local metadata unit having a description of a second new local RAID set, wherein the second new local RAID set is created, wherein the second new local RAID set includes the new disk and only a second disk from the previous RAID set.