Storage system with multiple copy targeting and disk failure protection

A method comprising:

• writing a data object to a source data image at one of a plurality of controlled storage apparatus;
• copying by a first copy component said data object to a first target data image at one of said plurality of controlled storage apparatus responsive to a first metadata state;
• responsive to a second metadata state performing, by a second copy component, a step selected from a group consisting of:
• controlling copying of said data object to a second target data image at one of said plurality of controlled storage apparatus;
• and
• causing said first copy component to perform copying of said second target data image to said first target data image;
• and
• cascaded copying of said data object to a third target data image at one of said plurality of controlled storage apparatus by a third copy component;
• wherein one of said second and said third copy components is operable to control cascaded copying of a delimited subsequence of data images responsive to a third metadata state indicating currency of a grain of data in one of said second and said third target data images.

A computer program product comprising:

• a computer useable medium having computer useable program code for operating a storage controller, said computer program product including:
• computer useable code for a host write component to write a data object to a source data image at one of a plurality of controlled storage apparatus;
• computer useable code for copying by a first copy component said data object to a first target data image at one of said plurality of controlled storage apparatus responsive to a first metadata state;
• and
• computer useable code, responsive to a second metadata state, for performing by a second copy component a step selected from a group consisting of:
• controlled copying of said data object to a second target data image at one of said plurality of controlled storage apparatus;
• and
• causing said first copy component to perform copying of said second target data image to said first target data image;
• and
• computer useable code for cascaded copying by a third copy component said data object to a third target image at one of said plurality of controlled storage apparatus.

A tool for managing a storage controller comprising:

• instructions for writing a data object to a source data image at one of a plurality of controlled storage apparatus;
• instructions for copying said data object to a first target data image at one of said plurality of controlled storage apparatus, wherein said instructions are responsive to a first metadata state;
• instructions responsive to a second metadata state for performing a step selected from a group consisting of:
• controlled copying of said data object to a second target data image at one of said plurality of controlled storage apparatus, and
• copying of said second target data image to said first target data image;
• instructions for cascaded copying by a third copy component said data object to a third target data image at one of said plurality of controlled storage apparatus, wherein one of said second and third copy components is operable to control cascaded copying of a delimited subsequence of data images responsive to a third metadata state indicating currency of a grain of data in one of said second and third target data images.