GAD operations are based on the global storage virtualization function. When virtual information is sent to the server in response to the SCSI Inquiry command, the server views multiple storage systems as multiple paths to a single storage system.
You need to install Resource Partition Manager only when you perform VSM manual configuration (in which you manually configure a virtual storage machine).
The server is able to identify multiple storage systems as a single virtual storage machine when the virtual information is set for the resources listed below. You can set virtual information on resource groups and on individual volumes, as described in the following table.
| Virtual information required by the server | Resource on which virtual information is set |
|---|---|
| Serial number | Resource group or volume |
| Product | Resource group or volume |
| LDEV ID* | Volume |
| Emulation type* | Volume |
| Number of concatenated LUs of LUN Expansion (LUSE)* | Volume |
| SSID* | Volume |
| * A volume whose virtual LDEV ID has been deleted cannot accept I/O from a server. You must delete the virtual LDEV ID and set the GAD reserve attribute on a volume to be used as a GAD S-VOL. When you create a GAD pair, the P-VOL's LDEV ID, emulation type, number of concatenated LUs of LUSE, and SSID are set as the S-VOL's virtual information. When you delete the GAD pair, these virtual information items are initialized, and the GAD reserve attribute is set for the LDEV ID. | |
The same virtual serial number and virtual model can be set for multiple resource groups and volumes. The maximum number of resource groups for which the virtual serial number and virtual model can be set is 1,023 per storage system (except resource group #0).
Depending on the DKCMAIN microcode version, the following limits apply to the number of combinations of virtual serial numbers and virtual models that can be defined per storage system:
- A0-05-41 or later: Maximum 63 combinations
- Earlier than A0-05-41: Maximum 15 combinations