Cache disk storage upgrade

A cache disk storage, comprising:

• a plurality of disk drive subunits configured to store data;
• and
• a cache control configured to establish a capacity restriction applicable to a filesystem spanning said plurality of disk drive subunits, said filesystem such that the active perceived available data storage capacity and unused capacity of said filesystem are spread across said plurality of disk drive subunits, and to periodically count a requested level of increments of available capacity of said cache disk storage, and determine whether there is a change from a current requested level of increments;
• and upon determining a change of requested level of increments, said cache control is configured to change said capacity restriction applicable to said filesystem spanning said plurality of disk drive subunits without adding disk drive subunits, said changed capacity restriction applicable to said filesystem such that the active perceived available data storage capacity and unused capacity of said filesystem are spread across said plurality of disk drive subunits, said changed capacity restriction related to said requested level of increments, said changed capacity restriction controlling rates of data transfer with respect to said filesystem.

A cache control configured to control the storage of data in a cache disk storage comprising a plurality of disk drive subunits configured to store data;

• said cache control comprising:
• a filesystem configured to store data spanning said plurality of disk drive subunits, said filesystem such that the active perceived available data storage capacity and unused capacity of said filesystem are spread across said plurality of disk drive subunits;
• and
• a cache capacity control configured to establish a capacity restriction applicable to said filesystem and to respond to a requested upgrade adjustment of available capacity of said cache disk storage, said cache capacity control establishing a new capacity restriction applicable to said filesystem without adding disk drive subunits, and said new capacity restriction related to said requested upgrade adjustment, said new capacity restriction controlling rates of data transfer with respect to said filesystem.

A computer program product comprising a computer useable medium having computer useable program code stored therein for operating a cache control controlling the storage of data in a cache disk storage comprising a plurality of disk drive subunits configured to store data;

• said cache control configured to store data as a filesystem;
• said computer useable program code configured to, when executed on said cache control, cause said cache control to:
• establish a capacity restriction applicable to said filesystem, said filesystem spanning said plurality of disk drive subunits such that the active perceived available data storage capacity and unused capacity of said filesystem are spread across said plurality of disk drive subunits;
• detect a requested upgrade adjustment of available capacity of said cache disk storage;
• and
• establish a new capacity restriction applicable to said filesystem without adding disk drive subunits, said new capacity restriction related to said requested upgrade adjustment, said filesystem spanning said plurality of disk drive subunits such that the active perceived available data storage capacity and unused capacity of said filesystem are spread across said plurality of disk drive subunits, said new capacity restriction controlling rates of data transfer with respect to said filesystem.

A service method of increasing active perceived data storage capacity of a cache disk storage comprising a plurality of disk drive subunits configured to store data, said data stored as a filesystem;

• comprising the steps of:
• establishing a capacity restriction applicable to said filesystem, said filesystem spanning said plurality of disk drive subunits such that the active perceived available data storage capacity and unused capacity of said filesystem are spread across said plurality of disk drive subunits;
• detecting a requested upgrade adjustment of available capacity of said cache disk storage;
• and
• establishing a new capacity restriction applicable to said filesystem without adding disk drive subunits, said filesystem spanning said plurality of disk drive subunits such that the active perceived available data storage capacity and unused capacity of said filesystem are spread across said plurality of disk drive subunits, said new capacity restriction related to said requested upgrade adjustment, and said new capacity restriction controlling rates of data transfer with respect to said filesystem.