Remote mirroring in a switched environment
View Patent ↗A mechanism to support remote mirroring of storage devices by data storage systems in a one-to-many switched environment. Each data storage system includes a disk director that is adapted to control at least one device group that is supported in a mirrored configuration with a corresponding device group controlled by one of the other data storage systems. For each device group and corresponding device group, there are first ports associated with the device group and second ports associated with the corresponding device group. A switch element is adapted to connect one of the first ports to at least one of the second ports so that data may be exchanged between the ports for each device group and corresponding device group. The disk director selects which first port is to be connected to which second port via the switch element in the establishment of a logical link. Thus, each port connected to the switch is capable of achieving multiple connections to multiple destinations for increased connectivity, redundancy and performance (load balance) without additional hardware.
1. In a remote data mirroring arrangement of data storage systems, a method of connecting ports on a data storage system to ports on other data storage systems comprising:
providing each storage system with configuration topology information;
determining from a switch fabric that connects to ports of all of the data storage systems information identifying ports of the other data storage systems connected to the switch fabric; and
using the configuration topology information and the information obtained from the switch fabric to establish a logical link between a port on the storage system and a second port on a second storage system so that data residing on a device group supported by the port and a corresponding, mirrored device group supported by the second port can be exchanged between the data storage system and the second data storage system.
2. The method of claim 1 , wherein the configuration topology information comprises configuration topology tables.
3. The method of claim 2 , wherein the configuration topology tables further comprise a device groups table identifying the device groups supported by the data storage system and providing for each of the device groups a pointer to one of the other data storage systems that serves the device group.
4. The method of claim 3 , wherein the configuration topology tables further comprise a remote systems table specifying by serial number each one of the other data storage systems that is pointed to by the pointer in the device groups table.
5. The method of claim 4 , wherein the configuration topology tables further comprise a processors table identifying by a unique name each processor in the data storage system and providing an associated pointer to any one or more of the device groups supported by such processor.
6. The method of claim 5 , wherein determining comprises:
receiving from the switch fabric a list of the ports of the other data storage systems, the list including for each of the ports a corresponding World Wide Name, the World Wide Name including unique names for processors and a serial number for the data storage system with which the port is associated.
7. The method of claim 6 , wherein using comprises:
determining if any of the device groups are served by the World Wide Name.
8. The method of claim 7 , wherein using further comprises:
determining if a serial number of one of the storage systems pointed to by any of the device groups matches the serial number included in the World Wide Name;
if a match exists, reading the unique processor name that is associated with the pointer that points to the matched device group; and
writing to a new link entry in a link table pointers to the unique processor name and the device group as well as a state value of one.
9. The method of claim 8 , wherein using further comprises:
performing a single link discovery for the port and the port having the World Wide Name.
10. The method of claim 9 , wherein the ports are state machines and wherein the single link discovery establishes the logical link when each of the state machines advances to a ‘0×FF’ state from a ‘1’ state.
11. The method of claim 10 , wherein performing the single link discovery comprises exchanging between the ports data from the respective configuration topology tables of the ports to determine if the data matches.
12. The method of claim 1 , wherein the switch fabric comprises a Fibre Channel switch fabric.
13. In a remote data mirroring arrangement of data storage systems, an apparatus for connecting ports on a data storage system to ports on other data storage systems comprising:
means for providing each storage system with configuration topology information:
means for determining from a switch fabric that connects to ports of all the data storage systems information identifying ports of the other data storage systems connected to the switch fabric; and
means for using the configuration topology information and the information obtained from the switch fabric to establish a logical link between a port on the storage system and a second port on a second storage system so that data residing on a device group supported by the port and a corresponding, mirrored device group supported by the second port can be exchanged between the data storage system and the second data storage system.
14. The apparatus of claim 13 , wherein the configuration topology information comprises configuration topology tables.
15. The apparatus of claim 14 , wherein the configuration topology tables further comprise a device groups table identifying the device groups supported by the data storage system and providing for each of the device groups a pointer to one of the other data storage systems that serves the device group.
16. The apparatus of claim 15 , wherein the configuration topology tables further comprise a remote systems table specifying by serial number each one of the other data storage systems that is pointed to by the pointer in the device groups table.
17. The apparatus of claim 16 , wherein the configuration topology tables further comprise a processors table identifying by a unique name each processor in the data storage system and providing an associated pointed to any one or more of the device groups supported by such processor.
18. The apparatus of claim 17 , wherein the means for determining comprises:
means for receiving from the switch fabric a list of the ports of the other data storage systems, the list including for each of the ports a corresponding World Wide Name, the World Wide Name including unique names for processors and a serial number for the data storage system with which the port is associated.
19. The apparatus of claim 18 , wherein the means for using comprises:
means for determining if any of the device groups are served by the World Wide Name.
20. The apparatus of claim 19 , wherein the means for using further comprises:
means for determining if a serial number of one of the storage systems pointed to by any of the device groups matches the serial number included in the World Wide Name:
means for reading the unique processor name that is associated with the pointer that points to the matched device group; and
means for writing to a new link entry in a link table pointers to the unique processor name and the device group as well as the state value of one.
21. The apparatus of claim 20 , wherein the means for using further comprises:
means for performing a single link discovery for the port and the port having the World Wide Name.
22. The apparatus of claim 21 , wherein the ports are state machines and wherein the single link discovery establishes the logical link when each of the state machines advances to a ‘0×FF’ state from a ‘1’ state.
23. The apparatus of claim 22 , wherein means for performing the single link discovery comprises means for exchanging between the ports data from the respective configuration topology tables of the ports to determine if the data matches.
24. The apparatus of claim 13 , wherein the switch fabric comprises a Fibre Channel switch fabric.