Techniques for managing state changes of a data storage system utilizing the object oriented paradigm

• US 7,634,496 B1
• Filed: 01/03/2006
• Issued: 12/15/2009
• Est. Priority Date: 01/03/2006
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Evans, T. David
• Primary Examiner(s): Wong; Don
• Assistant Examiner(s): XUE, BIN
• Application Number:
  US11/325,494
• Time in Patent Office: 1,442 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0632 by initialisation or re-initialisation of storage systems
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

A technique involves managing state changes of a data storage system in a computerized device configured to obtain object trees representing state information of the data storage system. The technique includes receiving a first object tree which represents the data storage system at a first time, and receiving a second object tree which represents the data storage system at a second time. The second time is after the first time. The technique further includes generating a set of tree comparison results from a comparison between the first object tree representing the data storage system at the first time and the second object tree representing the data storage system at the second time. The set of tree comparison results indicate whether state changes have occurred in the data storage system.

Claims

1. In a computerized device configured to obtain object trees representing state information of a data storage system, a method of managing state changes of the data storage system, the method comprising:

receiving a first object tree which represents the data storage system at a first time;

receiving a second object tree which represents the data storage system at a second time, the second time being after the first time; and

generating a set of tree comparison results from a comparison between the first object tree representing the data storage system at the first time and the second object tree representing the data storage system at the second time, the set of tree comparison results indicating whether state changes have occurred in the data storage system;

wherein;

receiving the first object tree which represents the data storage system at the first time includes receiving the first object tree, the first object tree including a first plurality of nodes logically connected in a first hierarchical manner, the first plurality of nodes representing an array of storage devices connected to the data storage system at the first time, the logical connections between the nodes of the first plurality of nodes representing a logical arrangement of the array of storage devices at the first time;

receiving the second object tree which represents the data storage system at the second time includes receiving the second object tree, the second object tree including a second plurality of nodes logically connected in a second hierarchical manner, the second plurality of nodes representing an array of storage devices connected to the data storage system at the second time, the logical connections between the nodes of the second plurality of nodes representing a logical arrangement of the array of storage devices at the second time;

the first object tree is a binary tree;

the second object tree is a binary tree;

a first node of the first plurality of nodes represents a first component of the array of storage devices;

a second node of the first plurality of nodes represents a second component of the array of storage devices, the first component being distinct from the second component;

a first node of the second plurality of nodes represents a third component of the array of storage devices;

a second node of the second plurality of nodes represents a fourth component of the array of storage devices, the third component being distinct from the fourth component;

the computerized device includes a kernel level machine state server and a user level object oriented application;

the kernel level machine state server is configured to provide object trees in response to polling operations by the user level object oriented application;

receiving the first object tree, receiving the second object tree, and generating the set of tree comparison results are carried out by the user level object oriented application;

the user level object oriented application is an agent running on the computerized device on behalf of external client hosts;

the data storage system is configured to store and retrieve data on behalf of the external client hosts;

the first object tree has nodes in a first tree form;

the second object tree has nodes in a second tree form; and

generating the set of tree comparison results includes;

identifying additional portions in the second tree form based on a comparison of the first tree form with the second tree form,

identifying removed portions from the second tree form based on a comparison of the first tree form with the second tree form, and

identifying data modifications based on a comparison of node data of the nodes of the first and second object trees.

2. The method of claim 1 wherein identifying the additional portions in the second tree form includes:

finding any sub-trees which are present in the second tree form but which do not exist in the first tree form.

3. The method of claim 1 wherein identifying the removed portions in the second tree form includes:

finding any sub-trees which do not exist in the second tree form but which are present in the first tree form.

4. The method of claim 1 wherein identifying data differences includes:

finding differences in the node data of the nodes of the first and second object trees.

5. The method of claim 1 wherein each node is a common generic object;

and wherein the method further comprises;

generating a new set of well-defined objects when at least one of additional portions in the second tree form have been identified, removed portions from the second tree form have been identified, and data modifications have been identified, and

refraining from generating the new set of well-defined objects when no additional portions in the second tree form have been identified, no removed portions from the second tree form have been identified, and no data modifications have been identified.

6. The method of claim 1, further comprising:

after generating the set of tree comparison results, saving the second object tree in memory and deleting the first object tree from memory.

7. The method of claim 6, further comprising:

receiving a third object tree which represents the data storage system at a third time, the third time being after the second time; and

generating another set of tree comparison results from a comparison between the second object tree representing the data storage system at the

second time and the third object tree representing the data storage system at the third time.

8. The method of claim 7 wherein receiving the third object tree and generating the other set of tree comparison results are performed in response to a timer configured to periodically poll for state changes of the data storage system.

9. The method of claim 7 wherein receiving the third object tree and generating the other set of tree comparison results are performed in response to a request from an external host of the data storage system thus providing a current state of the data storage system to the external host in an event driven manner.

15. The method of claim 1 wherein generating the set of tree comparison results includes:

traversing the first object tree and the second object tree on a node-by-node basis;

for each node of the first binary tree traversed, determining if a node is present at a corresponding location in the second binary tree, and if not, determining that storage devices corresponding to that node and all of its descendants have been removed from the data storage system between the first time and the second time;

for each node of the second binary tree traversed, determining if a node is present at a corresponding location in the first binary tree, and if not, determining that storage devices corresponding to that node and all of its descendants have been added to the data storage system between the first time and the second time;

for each node traversed which is present in corresponding locations in the first binary tree and the second binary tree, comparing that node of the first binary tree to the corresponding node of the second binary tree, and if data contained within the node of the first binary tree differs from data contained within the node of the second binary tree, then determining that storage devices corresponding to that node and all of its descendants have been changed between the first time and the second time.

16. The method of claim 15 wherein:

the method further comprises making a copy of the second binary tree;

traversing the second object tree on a node-by-node basis includes traversing the copy of the second binary tree;

the method further comprises;

for each node of the first binary tree traversed, if no node is present at the corresponding location in the second binary tree, then removing that node and all of its descendants from the first binary tree and storing that node and all of its descendants in a location specified for removed objects;

for each node of the copy of the second binary tree traversed, if no node is present at the corresponding location in the first binary tree, then removing that node and all of its descendants from the copy of the second binary tree and storing that node and all of its descendants in a location specified for added objects.

17. The method of claim 1 wherein generating the set of tree comparison results from the comparison between the first object tree and the second object tree includes:

directly comparing a plurality of nodes of the first object tree to a corresponding plurality of nodes of the second object tree without creating any intermediate structure based on the first object tree and without creating any intermediate structure based on the second object tree.

19. The method of claim 1 wherein:

the first component is an area of physical data storage identified by a first logical unit number (LUN);

the second component is an area of physical data storage identified by a second LUN, the first LUN being distinct from the second LUN;

the third component is an area of physical data storage identified by a third LUN; and

the fourth component is an area of physical data storage identified by a fourth LUN, the third LUN being distinct from the fourth LUN.

10. A computerized device to manage state changes of a data storage system, the computerized device comprising:

an interface;

memory; and

a controller coupled to the interface and the memory, the controller being configured to;

receive a first object tree which represents the data storage system at a first time,

receive a second object tree which represents the data storage system at a second time, the second time being after the first time, and

generate a set of tree comparison results from a comparison between the first object tree representing the data storage system at the first time and the second object tree representing the data storage system at the second time, the set of tree comparison results indicating whether state changes have occurred in the data storage system, the set of tree comparison results being stored in the memory and being externally accessible through the interface;

wherein;

the first object tree includes a first plurality of nodes logically connected in a first hierarchical manner, the first plurality of nodes representing an array of storage devices connected to the data storage system at the first time, the logical connections between the nodes of the first plurality of nodes representing a logical arrangement of the array of storage devices at the first time;

the second object tree includes a second plurality of nodes logically connected in a second hierarchical manner, the second plurality of nodes representing an array of storage devices connected to the data storage system at the second time, the logical connections between the nodes of the second plurality of nodes representing a logical arrangement of the array of storage devices at the second time;

the first object tree is a binary tree;

the second object tree is a binary tree;

a first node of the first plurality of nodes corresponds to a first component of the array of storage devices;

a second node of the first plurality of nodes corresponds to a second component of the array of storage devices, the first component being distinct from the second component;

a first node of the second plurality of nodes corresponds to a third component of the array of storage devices;

a second node of the second plurality of nodes corresponds to a fourth component of the array of storage devices, the third component being distinct from the fourth component;

the computerized device further comprises a kernel level machine state server;

the controller includes a user level object oriented application;

the kernel level machine state server is configured to provide object trees in response to polling operations by the user level object oriented application;

receiving the first object tree, receiving the second object tree, and generating the set of tree comparison results are carried out by the user level object oriented application;

the user level object oriented application is an agent running on the computerized device on behalf of external client hosts;

wherein the data storage system is configured to store and retrieve data on behalf of the external client hosts;

the first object tree has nodes in a first tree form;

the second object tree has nodes in a second tree form; and

the controller, when generating the set of tree comparison results, is configured to;

identify additional portions in the second tree form based on a comparison of the first tree form with the second tree form;

identify removed portions from the second tree form based on a comparison of the first tree form with the second tree form; and

identify data modifications based on a comparison of node data of the nodes of the first and second object trees.

11. The computerized device of claim 10 wherein each node is a common generic object;

and wherein the controller is further configured to;

generate a new set of well-defined objects when at least one of additional portions in the second tree form have been identified, removed portions from the second tree form have been identified, and data modifications have been identified, and

refrain from generating the new set of well-defined objects when no additional portions in the second tree form have been identified, no removed portions from the second tree form have been identified, and no data modifications have been identified.

12. The computerized device of claim 10 wherein the first object tree initially resides in the memory;

and wherein the controller is further configured to;

after generating the set of tree comparison results, save the second object tree in the memory and delete the first object tree from the memory.

13. The computerized device of claim 12 wherein the controller is further configured to:

receive a third object tree which represents the data storage system at a third time, the third time being after the second time; and

generate another set of tree comparison results from a comparison between the second object tree representing the data storage system at the second time and the third object tree representing the data storage system at the third time.

18. The computerized device of claim 10 wherein the controller, when generating the set of tree comparison results from the comparison between the first object tree and the second object tree is configured to:

directly compare a plurality of nodes of the first object tree to a corresponding plurality of nodes of the second object tree without creating any intermediate structure based on the first object tree and without creating any intermediate structure based on the second object tree.

20. The computerized device of claim 10 wherein:

the first component is an area of physical data storage identified by a first logical unit number (LUN);

the second component is an area of physical data storage identified by a second LUN, the first LUN being distinct from the second LUN;

the third component is an area of physical data storage identified by a third LUN; and

the fourth component is an area of physical data storage identified by a fourth LUN, the third LUN being distinct from the fourth LUN.

14. A computer program product that includes a computer readable storage medium having instructions stored thereon for managing state changes of a data storage system, such that the instructions, when carried out by a computerized device, cause the computerized device to:

receive a first object tree which represents the data storage system at a first time;

receive a second object tree which represents the data storage system at a second time, the second time being after the first time; and

generate a set of tree comparison results from a comparison between the first object tree representing the data storage system at the first time and the second object tree representing the data storage system at the second time, the set of tree comparison results indicating whether state changes have occurred in the data storage system;

wherein;

receiving the first object tree which represents the data storage system at the first time includes receiving the first object tree, the first object tree including a first plurality of nodes logically connected in a first hierarchical manner, the first plurality of nodes representing an array of storage devices connected to the data storage system at the first time, the logical connections between the nodes of the first plurality of nodes representing a logical arrangement of the array of storage devices at the first time;

receiving the second object tree which represents the data storage system at the second time includes receiving the second object tree, the second object tree including a second plurality of nodes logically connected in a second hierarchical manner, the second plurality of nodes representing an array of storage devices connected to the data storage system at the second time, the logical connections between the nodes of the second plurality of nodes representing a logical arrangement of the array of storage devices at the second time;

the first object tree is a binary tree;

the second object tree is a binary tree;

a first node of the first plurality of nodes represents a first component of the array of storage devices;

a second node of the first plurality of nodes represents a second component of the array of storage devices, the first component being distinct from the second component;

a first node of the second plurality of nodes represents a third component of the array of storage devices;

a second node of the second plurality of nodes represents a fourth component of the array of storage devices, the third component being distinct from the fourth component;

the computerized device includes a kernel level machine state server and a user level object oriented application;

the kernel level machine state server is configured to provide object trees in response to polling operations by the user level object oriented application;

receiving the first object tree, receiving the second object tree, and generating the set of tree comparison results are carried out by the user level object oriented application;

the user level object oriented application is an agent running on the computerized device on behalf of external client hosts;

the data storage system is configured to store and retrieve data on behalf of the external client hosts;

the first object tree has nodes in a first tree form;

the second object tree has nodes in a second tree form; and

the instructions, when carried out by the computerized device, cause the computerized device to, when generating the set of tree comparison results;

identify additional portions in the second tree form based on a comparison of the first tree form with the second tree form;

identify removed portions from the second tree form based on a comparison of the first tree form with the second tree form; and

identify data modifications based on a comparison of node data of the nodes of the first and second object trees.

21. The computer program product of claim 14 wherein:

the first component is an area of physical data storage identified by a first logical unit number (LUN);

the second component is an area of physical data storage identified by a second LUN, the first LUN being distinct from the second LUN;

the third component is an area of physical data storage identified by a third LUN; and

the fourth component is an area of physical data storage identified by a fourth LUN, the third LUN being distinct from the fourth LUN.