Method and structure for adapting a storage virtualization scheme using transformations

1 . A method implemented in software or hardware for transforming a first storage virtualization (SV) composite function into a second SV composite function, comprising:

a) specifying a target form for the second SV composite function, said target form including a sequence of atomic function types taken from a set including concatenate, mirror, and stripe types;

b) transforming in logic executed in a digital electronic device the first composite function into an intermediate SV composite function having SV-normal form by applying rules from a set of transformation rules; and

c) transforming in logic executed in a digital electronic device by applying rules from the set of transformation rules the intermediate SV composite function into a second SV composite function, said second composite function describing a sequence of atomic functions that is identical to the target form.

2 . The method of claim 1 , wherein the first SV composite function is represented in an object-oriented form.

3 . An apparatus for storage virtualization, comprising:

a) a hardware or software adapter for transforming a first storage virtualization (SV) composite function into a second SV composite function;

b) logic in the adapter in the adapter to receive a target form for the second SV composite function, said target form including a sequence of atomic function types taken from a set including concatenate, mirror, and stripe types;

c) logic in the adapter to transform the first composite function into an intermediate SV composite function having SV-normal form by applying rules from a set of transformation rules; and

d) logic in the adapter to transform by applying rules from the set of transformation rules the intermediate SV composite function into a second SV composite function, said second composite function describing a sequence of atomic functions that is identical to the target form.

4 . The apparatus of claim 3 , wherein the first SV composite function is represented in an object-oriented form.

5 . The apparatus of claim 3 , wherein the adapter is contained in a network processor, a universal storage application, a host computer, a network adapted storage device, a switch, a director, a Fibre Channel fabric, or a RAID array.

6 . The apparatus of claim 3 , wherein the adapter is contained in a host subsystem, a network subsystem, or a physical storage subsystem.

7 . A method implemented in software or hardware for distributing storage virtualization functionality between two storage subsystems, comprising:

a) selecting a sequence of atomic function types defining an SV-normal form;

b) receiving a data structure describing a first SV-balanced tree;

c) transforming the first SV-balanced tree into a second tree having the SV-normal form;

d) partitioning the second tree into first and second parts;

e) transmitting the first part to a first storage subsystem and the second part to a second storage subsystem; and

f) receiving each part by the respective subsystem.

8 . The method of claim 7 , wherein each subsystem is taken from a set including a host subsystem, a network subsystem, a physical storage subsystem, and a RAID array within a physical storage subsystem.

9 . The method of claim 7 , wherein the first storage subsystem is implemented in a Fibre Channel fabric.

10 . The method of claim 7 , further comprising:

g) transforming the first part into a data structure describing an SV-balanced tree in the SV-normal form within the first storage subsystem.

11 . The method of claim 7 , further comprising:

g) transforming the first part into a data structure describing a tree in a local normal form within the first storage subsystem.

12 . A method implemented in software or hardware for remote mirroring of a virtual disk, comprising:

a) selecting a sequence of atomic function types defining an SV-normal form including a level having a mirror type;

b) receiving an input data structure;

c) transforming the input data structure into an output data structure by applying transform logic, wherein the input and output tree structures each describe a respective SV-balanced tree, each tree containing levels of nodes, each level having a respective type and a respective fan number, said type and fan number applicable to all nodes in that level, a top level having a type of virtual disk (vDisk) and a fan number of 1 and containing a single node, a bottom level having a type of either vDisk or physical disk, and at least one intermediate level having a type taken from the set of atomic function types; and

d) deploying the subtree whose root is the first child node to a first location; and

e) deploying the subtree whose root is the second child node to a second location.