Processing devices or a path to devices attached to a control unit

Use the VARY CU command to process devices or a path to devices attached to a control unit. For example, you can:

Vary all devices attached to a control unit online or offline.
Define all tape devices attached to a control unit as automatically switchable.
Make all tape devices attached to a control unit unavailable or available.
Vary a CHPID to all devices attached to a control unit online or offline.

Note: Because the VARY CU command starts VARY DEVICE or VARY PATH operations, you need to be familiar with VARY DEVICE and VARY PATH command operations, restrictions, warnings and the functions of the keywords for these commands. For more information on VARY DEVICE and VARY PATH, see:

For one of the error cases listed in message IEE902I, an error message is issued to the console. Otherwise, VARY DEVICE or VARY PATH operations are initiated on devices attached to a control unit. For details about message IEE902I, see z/OS MVS System Messages, Vol 7 (IEB-IEE).

Note: VARY DEVICE or VARY PATH operations started as a result of a VARY CU command cause individual messages to be generated for each device or path being processed. Because no message consolidation or message suppressing is done, a large number of messages may be issued to the console. You need to ensure that the VARY CU command is not excessively issued.

The syntax of the VARY CU command is:

 
V CU {(cunumber)},{ONLINE[,UNCOND[,FORCE] | ,SHR | ,RESET]}
                  {OFFLINE[,FORCE]                        }
                  {AUTOSWITCH | AS [,ON | OFF]            }
                  {UNAVAILABLE | UNAVAIL]                 }
                  {AVAILABLE | AVAIL]                     }
V CU {(cunumber,chpid)},{ONLINE[,FORCE]           }
                        {OFFLINE[,UNCOND | ,FORCE]}

Default: None

Note:

Only one control unit or one channel path can be specified at a time.
When issued on a console, the VARY CU command keywords listed above propagate to each device, device pair, or chpid pair to be processed. They perform the same functions when used with a VARY DEVICE or a VARY PATH command.
Certain keywords or parameters are valid for certain requests or for certain device types only. For example, OFFLINE,UNCOND is acceptable for a VARY PATH request, but is not acceptable for a VARY DEVICE request. AUTOSWITCH can only be used for tape devices. The VARY CU syntax checker also recognizes these cases and issues error messages.

cunumber: The control unit number. When a VARY CU command is issued with cunumber only, VARY DEVICE operations are performed on all the devices attached to the control unit.
chpid]: The channel path associated with the devices attached to the control unit. When a VARY CU command is issued with a CU number and a CHPID, VARY PATH operations are performed on the specified chpid of all devices attached to the control unit.