IBM United States
Hardware Announcement 102-181
June 25, 2002
System Managed Coupling Facility (CF) Structure Duplexing Extends Parallel Sysplex Architecture
At a Glance
The World Wide Early Support Program for System Managed CF Structure Duplexing began during the first week of June 2002. IBM plans to make System Managed CF Structure Duplexing available before the end of 2002. Those customers who have a business need to use System Managed CF Structure Duplexing earlier should contact their IBM representative for information on the CF duplexing early support program.
For ordering, contact:
Your IBM representative, an IBM Business Partner, or IBM Americas Call Centers at 800-IBM-CALL (Reference: YE001).
IBM plans to make System Managed CF Structure Duplexing available before the end of 2002. It will be enabled by APAR OW41617 on z/OS V1.2, V1.3, and V1.4, and will require:
A set of architectural extensions to the Parallel Sysplex® is introduced for the support of System-Managed CF structure duplexing of coupling facility structures for high availability. All three structure types (cache structures, list structures, and locking structures) can be duplexed using this architecture. This new set of features is quite extensive and, in total, represents a significant extension to the Parallel Sysplex Architecture.
Support for these extensions will be included in Coupling Facility Control Code (CFCC) Levels 11 and 12, and in z/OS V1.2, V1.3, and V1.4 with enabling APAR OW41617, and any additional APARS as listed in the CFDuplexing PSP bucket. Considerations for key exploiters of this new function will be included in V3 of the technical paper, "System Managed CF Structure Duplexing" (GM13-0103-3). Installing this software and microcode and enabling this new function is designed to:
For those CF structures that support use of System Managed CF Structure Duplexing, customers can dynamically enable (selectively by structure) or disable the use of CF duplexing.
V3 of the IBM technical paper, "System Managed CF Structure Duplexing" (GM13-0103-3), will include information on determining:
This paper will be available at either:
The most visible change for CF duplexing is the requirement to connect coupling facilities to each other with coupling links. The required connectivity is bi-directional with a sender and receiver channel attached to each CF for each remote CF connection. For peer-mode links (ISC-3, ICB-3, IC-3), a single channel provides both the sender and receiver capabilities; therefore, only one physical link is required between each pair of CFs. For compatibility mode links, two links are required to establish a connection, with a sender and receiver channel located in each CF. If redundancy is included for availability, then two peer-mode links or four compatibility mode links are required. However, this new connectivity requirement does not necessarily imply any requirement for additional physical links. Peer-mode channels can be shared between one ICF partition and many local z/OS partitions, so existing links between zSeries servers can provide the connectivity between both:
Support for configuring sender channels (CFS, CBS, and ICS) to a CF is contained in zSeries, G5, G6, and R06, and support for sharing the sender channels between an ICF partition and multiple z/OS partitions is contained in zSeries, G5, and G6.
One of the benefits of System-Managed CF Structure Duplexing is to help hide coupling facility failures and structure failures and to make total loss of CF connectivity incidents transparent to the exploiters of the coupling facility. This is handled by:
System messages are generated as the structure reverts to simplex mode for monitoring and automation. Until a new duplexed structure is established, the structure will operate in simplex mode and may be recovered through whatever mechanism is provided for structure recovery before the advent of System Managed CF structure duplexing.
As the two instances of a System Managed Duplexed structure get update requests, they must coordinate execution of the two commands to ensure that the updates are made consistently to both structures. Most read operations do not need to be duplexed.
New operator commands are being extended in z/OS to display the status of the new links for problem determination. In addition, the Resource Measurement Facility (RMF) as of z/OS 1.2 is designed to provide the performance management aspects about the new CF-CF connectivity and the duplexed structures. Together, these enable the installation to manage and monitor the CF configuration and the new structure instances resulting from System-Managed CF Structure Duplexing.
Use Priority/Reference Code: YE001 Phone: 800-IBM-CALL Fax: 800-2IBM-FAX Internet: firstname.lastname@example.org Mail: IBM Atlanta Sales Center Dept. YE001 P.O. Box 2690 Atlanta, GA 30301-2690
You can also contact your local IBM Business Partner or IBM representative. To identify them, call 800-IBM-4YOU.
Note: Shipments will begin after the planned availability date.