# Cross System Volume Summary

The Cross System Volume attributes provide an overview of the performance of a logical device across multiple z/OS® images, that is, it helps to identify problems with shared DASD.

Control Unit Model: The model number associated with this control unit.

Cumulative I/O Rate: Represents the sum of I/O rates for all sharing systems.

Device Contention Index: The percentage of time that I/Os to the device are delayed (pending), averaged for all sharing systems. This is a measure of the time that each system spends waiting for the device.

Device Model: The model of DASD. Device geometry for the most common models or their equivalents are as follows:

Model | Tracks | Cylinders | Paths | Density
--- | --- | --- | --- | ---
3390-1 | 16685 | 1113 | 4 | TRIPLE
3390-2 | 33390 | 2226 | 4 | TRIPLE
3390-3 | 50055 | 3339 | 4 | TRIPLE
3380-K | 39825 | 2655 | 4 | TRIPLE
3380-J | 13275 | 885 | 4 | SINGLE
3380-E | 26550 | 1770 | 2 | DUAL
3380-A | 13275 | 885 | 2 | SINGLE
3375 | 11508 | 959 | 2 | SINGLE
3350 | 16650 | 555 | 2 | SINGLE

High Disconnect Time System: The SMFID of the sharing system reporting the highest disconnect time for this volume.

High Disconnect Time Value: The highest disconnect time reported by any sharing system.

High MSR System: The SMFID of the sharing system reporting the highest MSR (millisecond response time) value for this volume.

High MSR Value: Represents the highest MSR (millisecond response time) time reported by any sharing system.

Managed System: The SMS name of this system.

Storage Group Name: The 32-character name of the SMS storage group to which this volume belongs.

True % Busy: The percentage of time a device is busy as a result of activity from all sharing systems. This is a measure of the time that the device spends actually doing work.

User DASD Grp Name: The name of the user DASD group to which this volume belongs. User DASD group is an OMEGAMON II® facility that enables you to define groups of DASD volumes by VOLSER and device address. You can also specify generic VOLSERs and devices (patterns) by using the wildcard character.

This feature gives you the flexibility of having OMEGAMON II report the performance and status of any combination of DASD volumes as a single entity. User DASD groups can include both SMS managed volumes and non-SMS managed volumes.

User_Group\Name: The user-assigned name for a group of DASD volumes.

Volume: The six-character identifier assigned to a DASD or tape volume. Also known as the volume serial number or volume ID.