8464ch02_Architecture.fm Draft Document for Review February 7, 2020 3:15 pm The customer can decide when the cluster returns to an operational state from service if an  automatic online (AONLINE) to supported z/OS LPARs is run. Then, the logical paths that are  established from the system zLPAR that the cluster surfaced the unsolicited attention receive  an unsolicited attention to request the zLPAR to vary the devices back online. Only z/OS  LPARs support the CUIR function. Other IBM Z operating systems can exist and hold up  service-prep until you manually vary off their devices. If the customer decides not to use AONLINE, the devices must be varied online again by  using the MI. The original z/OS command ( Vary Online ) cannot be used to online the devices  in the z/LPAR while in CUIR. The manual function (through the MI) must be used to online the  drives that CUIR put offline. As of this writing, no option is available to bring online drives only  partially (for example, to test a system) for quality assurance tests before the cluster is varied  online to all systems again. Note:  If a device is varied offline for CUIR reasons and is unintentionally left in this state,  the  MVS VARY XXXX,RESET  command can be used to reset the device for CUIR reasons.  This command should only be used if devices exist that are left in this state and should no  longer be in this state.  CUIR features the following limitations:  The following APARs must be installed: New  LI REQ  commands are provided to enable or disable CUIR and AONLINE and to get an  overview of the current logical drive or path group information. The default is disabled.  For more information, see  IBM TS7700 Series Control Unit Initiated Reconfiguration (CUIR)  User’s Guide , WP102743. Several grid configuration examples are provided in this section. These examples describe  the requirements for high availability (HA) and DR planning.  Homogeneous configurations contain only TS7700Ds, TS7700Ts, or TS7700Cs. If you use  an intermix of disk-only and tape-attached models, it is a  hybrid configuration . Consider the  information that is provided in this section when you choose whether a mixture of the types is  best for you. 100  IBM TS7700 Release 5.0 Guide 2.5 Grid configuration examples 2.5.1 Homogeneous versus hybrid grid configuration GLYPH<SM590000> OA52398 GLYPH<SM590000> OA52390 GLYPH<SM590000> OA52376 GLYPH<SM590000> OA52379 GLYPH<SM590000> OA52381 GLYPH<SM590000> Can be enabled only when all clusters in grid are at R4.1.2 or later. GLYPH<SM590000> Only native LPARS with z/OS 2.2 or later and JES2 can use CUIR. Other setups can exist,  but their devices must be manually varied offline and back online.  GLYPH<SM590000> Only Service preparation/Service mode is supported. The CUIR function might be  extended in the future.