Storage system capacity expansion using mixed-capacity storage devices

An apparatus comprising:

• a storage system comprising a plurality of storage devices;
• the storage devices comprising a first set of storage devices each having a first capacity and a second set of storage devices each having a second capacity higher than the first capacity;
• wherein the storage system is implemented as a distributed storage system that comprises a plurality of storage nodes each having a processor coupled to a memory and each comprising a corresponding subset of the storage devices;
• the storage system being configured:
• to establish an extended redundant array of independent disks (RAID) group to extend existing RAID stripes of the storage devices of the first set into the storage devices of the second set;
• and
• to establish an additional RAID group for the storage devices of the second set, the additional RAID group comprising one or more additional RAID stripes for the storage devices of the second set.

An apparatus comprising:

• a storage system comprising a plurality of storage devices;
• the storage devices comprising a first set of storage devices each having a first capacity and a second set of storage devices each having a second capacity higher than the first capacity;
• the storage system being configured:
• to establish an extended redundant array of independent disks (RAID) group to extend existing RAID stripes of the storage devices of the first set into the storage devices of the second set;
• and
• to establish an additional RAID group for the storage devices of the second set, the additional RAID group comprising one or more additional RAID stripes for the storage devices of the second set;
• wherein data pages are stored across the storage devices of the extended and additional RAID groups using multiple RAID layers, wherein a size of a given one of the RAID layers is larger for the storage devices of the second set than it is for the storage devices of the first set.

A method for use in a storage system comprising a plurality of storage devices, the storage devices comprising a first set of storage devices each having a first capacity and a second set of storage devices each having a second capacity higher than the first capacity, the method comprising:

• establishing an extended redundant array of independent disks (RAID) group to extend existing RAID stripes of the storage devices of the first set into the storage devices of the second set;
• and
• establishing an additional RAID group for the storage devices of the second set, the additional RAID group comprising one or more additional RAID stripes for the storage devices of the second set;
• wherein an extended RAID stripe of the extended RAID group has a number of columns equal to a sum of the number of storage devices of the first set and the number of storage devices of the second set.

A computer program product comprising a non-transitory processor-readable storage medium having stored therein program code of one or more software programs, wherein the program code when executed by a storage system comprising a plurality of storage devices, the storage devices comprising a first set of storage devices each having a first capacity and a second set of storage devices each having a second capacity higher than the first capacity, causes the storage system:

• to establish an extended redundant array of independent disks (RAID) group to extend existing RAID stripes of the storage devices of the first set into the storage devices of the second set;
• and
• to establish an additional RAID group for the storage devices of the second set, the additional RAID group comprising one or more additional RAID stripes for the storage devices of the second set;
• wherein an extended RAID stripe of the extended RAID group has a number of columns equal to a sum of the number of storage devices of the first set and the number of storage devices of the second set.