Increasing provisioned storage capacity by means of growing underlying disks within a storage appliance

A non-transitory machine readable medium storing instructions, which when executed by one or more processing resources of a storage system, cause the storage system to:

• for each disk of a plurality of disks available for use by the storage system, provision a portion of a logical size of the disk to a file system of the storage system, wherein the provisioned portion represents a storage capacity of the disk currently available for use by the file system and wherein the storage capacity may grow over time;
• maintain a sparse space for a plurality of file system disks of the storage system, wherein the sparse space comprises a contiguous sequence of block numbers in which respective portions of the sparse space are associated with corresponding file system disks of the plurality of file system disks, wherein each of the plurality of file system disks corresponds to one of the plurality of disks, wherein maintaining the sparse space includes accommodating subsequent dynamic growth of the plurality of file system disks, by pre-allocating block numbers for each of the plurality of file system disks within the respective portions of the sparse space corresponding to a number of blocks represented by the logical size of the corresponding disk, and wherein each of the plurality of file system disks is backed by the provisioned portion of the corresponding disk;
• for each of the plurality of file system disks, maintain file system metadata regarding a range of the pre-allocated block numbers that are available for use;
• after detecting a triggering condition, cause the provisioned portion of a disk of the plurality of disks to be increased;
• and
• after detecting a change in the storage capacity of the disk, updating within the file system metadata a size of a file system disk of the plurality of file system disks to which the disk corresponds.

A storage system comprising:

• one or more processing resources;
• and
• a non-transitory computer-readable medium, coupled to the one or more processing resources, having stored therein instructions that when executed by the one or more processing resources cause the storage system to:
• for each disk of a plurality of disks available for use by the storage system, provision a portion of a logical size of the disk to a file system of the storage system, wherein the provisioned portion represents a storage capacity of the disk currently available for use by the file system and wherein the storage capacity may grow over time;
• maintain a sparse space for a plurality of file system disks of the storage system, wherein the sparse space comprises a contiguous sequence of block numbers in which respective portions of the sparse space are associated with corresponding file system disks of the plurality of file system disks, wherein each of the plurality of file system disks corresponds to one of the plurality of disks, wherein maintaining the sparse space includes accommodating subsequent dynamic growth of the plurality of file system disks, by pre-allocating block numbers for each of the plurality of file system disks within the respective portions of the sparse space corresponding to a number of blocks represented by the logical size of the corresponding disk, and wherein each of the plurality of file system disks is backed by the provisioned portion of the corresponding disk;
• for each of the plurality of file system disks, maintain file system metadata regarding a range of the pre-allocated block numbers that are available for use;
• after detecting a triggering condition, cause the provisioned portion of a disk of the plurality of disks to be increased;
• and
• after detecting a change in the storage capacity of the disk, updating within the file system metadata a size of a file system disk of the plurality of file system disks to which the disk corresponds.