HP XP24000, XP20000 manual Guidelines for Mainframe Volumes, Volume Attribute Guidelines

smaller than the actual external volume capacity. The available capacity decreases as much capacity as the data management information area.

Figure 20 (page 41) shows an example of when the original capacity of the external volume is bigger than the basic capacity of the emulation type. The emulation type is OPEN-3. Figure 21 (page 41) shows an example of when the original capacity of the external volume is smaller than the basic capacity of the emulation type.

Figure 20 When the External Volume Capacity is Bigger than the Basic Capacity of Specified Emulation Type (Example of the OPEN-3 emulation type)

Figure 21 When the External Volume Capacity is Smaller than the Basic Capacity of Specified Emulation Type

Guidelines for Mainframe Volumes

•If you plan to use the mapped external volume from the mainframe operating system (for example, the volume is mapped with the setting of 3390–x mainframe emulation type), you need to select the external volume that consists of one LDEV or you need to adjust the capacity of the external volume to be mapped beforehand. If multiple LDEVs exist in one external volume and if a lot of I/Os are made to these LDEVs, the read, write commands may time out. When the commands may time out, the SIM (21D2xx) is reported.

•When you use the mapped external volume from the mainframe operating system, set the MIH (Missing Interrupt Handler) timer to 45 seconds (which is the recommended value).

Volume Attribute Guidelines

•The external volume attributes for all the LDEVs created in an external volume become the same. The attributes are taken over, when the LDEVs are reconfigured using the VLL function.

•The Cache Mode becomes the same for all the LDEVs in one external volume.

Guidelines for XP External Storage Operations 41