Mainframe volumes

When you map mainframe external volumes, there are many requirements and considerations to keep in mind.

Note the following requirements and considerations for mapping mainframe external volumes:

• (VSP 5000 series) The external volumes that use iSCSI for the external paths cannot be accessed from a mainframe operating system. (The emulation types such as 3390-x cannot be set for the external volumes.)
• Make sure that mainframe external volumes on a mainframe operating system consist of at least one LDEV before mapping.
• When multiple LDEVs exist in an external volume and numerous I/Os are made to them, read/write commands might timeout. When the commands timeout, the SIM (21d2xx) is reported.
• Set the MIH (missing interrupt handler) timer to 45 seconds (which is the recommended value) for mainframe external volumes on a mainframe operating system.
• Pre-existing mainframe volumes on an external storage system cannot be directly connected to the local storage system as external volumes.

You can prepare mainframe external volumes for mapping using one of the following methods:

• Zero-format the external volumes on the external system, map the volumes to the local storage system, then perform the Write to Control Blocks operation on the local system side.
• Map the external volumes to the local storage system and then format the mapped volumes on the local storage system.

  After the mapping operation completes, the status of the mapped volume is Blockade; however, after the Write to Control Blocks operation completes or the mapped volume is formatted on the local system, the mainframe host can access the new mainframe volume through the FICON channels of the local storage system.