z/VM: CP Commands and Utilities Reference - z/VM - IBM

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ATTACH
Usage Notes
30 z/VM: CP Commands and Utilities Reference
NOQIOAssist
indicates that the devices are not eligible for Queued-I/O assist.
USERACCessid userid
to allow a user (guest) the ability to give FCP LUN access to the specified
userid. This is a shortcut to redefining entries in the Access Control Table
(ACT), and assumes the user has authority to the LUN as defined in the ACT.
Please refer to Linux documentation for details on creating and maintaining the
ACT for FCP configuration.
1. If you are attaching a DASD with logical addresses, the real device number
you specify must be the base address for the device, and the virtual device
number you specify must follow the addressing rules for base addresses.
2. If you mount and ready a device that contains virtual minidisks after you have
loaded VM onto the system, you must attach that device to the system if you
want to use it. If you log on after the device has been attached, you gain
access to the disk as provided by your entry in the system directory. If you
were logged on before the volume was attached to the system, you must use
the CP LINK command to gain access to the virtual disks.
3. CP processes all the device numbers you specify, even if it encounters errors
when attempting to attach the devices. So, if you enter: attach 108-10f user1
r and real devices 10A and 10D were not ready and online, the following
devices would be successfully attached: 108, 109, 10B, 10C, 10E, 10F.
Messages tell you whether devices are successfully attached.
4. You can use the system directory DEDICATE statement to attach real devices
to each virtual machine. Then, when users successfully log on, the devices (if
online and available) are automatically attached to their virtual machine. This
function saves Class B users the trouble of issuing multiple ATTACH
commands for the devices.
5. The ATTACH XSTORE command allows a Class B operator to assign
Expanded Storage to a guest virtual machine without authorization in the user
directory. The size operand in this command allows the operator to attach any
size up to the maximum Expanded Storage allowed for guest use on the
system, regardless of the user directory limit. The maximum allowed for a
guest virtual machine is the total of Expanded Storage, less what is retained
by the system. For more information, see the RETAIN XSTORE command.
The size parameter must be in units of 1 MB. The size of the Expanded
Storage feature dedicated to the guest is displayed on the response to the
originator of the command, as well as to the owner of the Expanded Storage.
When the user issues QUERY XSTORE, the dedicated Expanded Storage for
a user appears as an Expanded Storage feature equal to the size provided in
the ATTACH XSTORE command. The actual size of Expanded Storage
depends on whether any nonconfigured Expanded Storage exists within the
user’s partition.
6. The system directory XSTORE statement directs CP to attach Expanded
Storage to a virtual machine during logon. When logon is complete, Expanded
Storage (if available) is automatically attached to the user’s virtual machine.
7. When running on a partitioned processor, the amount of Expanded Storage
attached to a user may appear larger than the amount requested. For
example, a processor with 128 MB of Expanded Storage may be partitioned
with 64 MB of XSTORE on each side. In this example, the lower block
addresses are on one side, the “A” side, and the higher block addresses are
on the other side, the “B” side. With CP running on the “B” side, attaching 4