GDPS and System Complex
- 1. G D P S A N D S Y S T E M C O M P L E X M A I N F R A M E C L U S T E R I N G Najmi Mansoor Ahmed Principal Architect PSS (IBM ALCS v241 under z/OS 2.1) Presented on 23-Nov-2016
- 2. BASICS • A system is made up of hardware products including a central processor (CPU), and software products, with the primary one being an operating system such as z/OS. • The CPU and other system hardware, such as channels and storage (RAM), make up a Central Processor Complex (CPC) or in general terms – mainframe box. Mainframe Disks
- 3. • It is possible to run mainframe with a single processor /uniprocessor (CP) , but this is not a typical system. • When all the CPs share central storage and a single OS image manages the processing, work is assigned to a CP that is available to do the work. If a CP fails, work can be routed to another CP. Mainframe Disks z/OS CP1 Multi and Uniprocessor The ability to partition a large system into multiple smaller systems, called logical partitions or LPARs, is now a core requirement in practically all mainframe installations.
- 4. It allows to build virtual clusters of CPUs, OSs and applications with in a single box Multi and Uniprocessor
- 5. • Mainframe has three major clustering techniques: LPAR Channels z/OS Disk control unit Clustering LPAR Channels z/OS Disk control unit Basic Shared Storage (DASD) It is typically used when operations staff controls which jobs go to which system and ensures that there is no conflict (both system trying to update same data at the same time) A channel is a high-speed data bus. Todays mainframe use FICON (FIber CONnection) channels. • Basic Shared DASD • CTC rings • Parallel Sysplex
- 6. • Channel-to-Channel CTC ring LPAR Channels z/OS Disk control unit Clustering LPAR Channels z/OS Disk control unit Channel-to-Channel (CTC) It simulates an I/O device that can be used by one system to communicate with another and provides data path and synchronization for data transfer When CTC is used to connect two channels a loosely coupled multiprocessing system is established CTC ring
- 7. • A loosely coupled configuration has more than one mainframes managed by more than one z/OS image. • Although a loosely coupled configuration increases system capacity, it is not as easy to manage as either a uniprocessor or a tightly coupled multiprocessor. • Each system must be managed separately, often by a human operator, who monitors product-specific messages on a set of consoles for each system. • Products and applications that need to communicate and are running on separate systems have to create their own communication mechanism. Loosely coupled multiprocessors CP4CP3CP2CP1 z/OS Image CP4CP3CP2CP1 z/OS Image
- 8. • To help solve the difficulties of managing many z/OS systems, IBM introduced the z/OS systems complex or sysplex • A sysplex is a collection of z/OS systems that cooperate, using certain hardware and software products, to process work. Sysplex Mainframe 4 Disks Mainframe 3 Disks Mainframe 2 Disks Mainframe 1
- 9. • SYSPLEX - System Complex - Is clustering more systems for availability, sharing workload, recovery, resource and data sharing. • System complex can be build in same data centre or in two different data centres from 2 to 32 mainframes Sysplex Mainframe 4Mainframe 3Mainframe 2Mainframe 1
- 10. SYSPLEX It is a Clustering technique • Every server (node) / LPAR has access to data resources • Every cloned sysplex enabled application can run on every LPAR • It appears as single large system having single operating interface to control it
- 11. SYSPLEX
- 12. Base Sysplex • Joining systems through Channel to Channel (CTC) connections Types of Sysplex LPAR Channels z/OS Disk control unit LPAR Channels z/OS Disk control unit CTC ring
- 13. PARALLEL SYSPLEX A Parallel Sysplex is a cluster of IBM mainframes acting together as a single system image with z/OS. Used for disaster recovery, Parallel Sysplex combines data sharing and parallel computing to allow a cluster of up to 32 systems to share a workload for high performance and high availability.
- 14. PARALLEL SYSPLEX Parallel Sysplex = Base Sysplex + Coupling Facility (CF) Mainframe 1 Mainframe 2 Site A Site B System Complex - SysPlex
- 15. Parallel Sysplex • An enhancement to Base Sysplex by joining systems through a Facility (CF) Types of Sysplex LPAR Channels z/OS Disk control unit LPAR Channels z/OS Disk control unit CTC ring Coupling Facility CF channels
- 16. Types of Sysplex LPAR Channels z/OS Disk control unit LPAR Channels z/OS Disk control unit CTC ring Coupling Facility CF channels; Parallel Sysplex technology is an enabling technology with two critical capabilities Parallel processing Enabling read/write data sharing across multiple systems with full data integrity. "shared data" (as opposed to "shared nothing") DisksDisks
- 17. A key component in any Parallel Sysplex is the Coupling Facility (CF) infrastructure. Coupling facility = sharing of central memory between two systems. Parallel Sysplex Parallel Sysplex is analogous in concept to a UNIX cluster – allow the customer to operate multiple copies of the operating system as a single system. This allows systems to be added or removed as needed, while applications continue to run. PrimarySecondary System Complex (Clustering) System Complex (Clustering) Standby Production Production Non Production Standby Non Production
- 18. • A coupling facility is a special logical partition that runs the coupling facility control code (CFCC) and provides high-speed caching, list processing, and locking functions in a sysplex. • A CF functions largely as a fast scratch pad. It is used for three purposes: Coupling Facility (CF) structure Locking information that is shared among all attached systems Cache information (such as for a database) that is shared among all attached systems Data list information that is shared among all attached systems
- 19. Characteristics of Parallel Sysplex A common time source to synchronize all Mainframes systems' clocks. Coupling facility (CF) sharing of central memory between two systems for high performance data sharing Cross System Coupling Facility (XCF) allows systems to communicate peer-to- peer Global Resource Serialization (GRS) allows multiple systems to access the same resources concurrently, serializing where necessary to ensure exclusive access to prevents updates to the same data Couple Data Sets (CDS) requires by sysplex to store information about its systems FICON Sysplex Timer Coupling Facility XCF XCF GRS GRS z/OS LPAR z/OS LPAR Couple Data Sets Couple Data Sets CDS CDS
- 20. Characteristics of Parallel Sysplex • The best practice for any data sharing Parallel Sysplex is that there is at least one failure-isolated CF implemented. • It is critical that all Parallel Sysplex have at least two CFs to every member of sysplex FICON Sysplex Timer Coupling Facility XCF XCF GRS GRS z/OS LPAR z/OS LPAR CF CF Couple Data Sets Couple Data Sets CDS CDS
- 21. Characteristics of Parallel Sysplex Timer is a mandatory hardware requirement for a parallel sysplex consisting of more than one z Series servers. It provides synchronization for the time-of-day (TOD) clocks of multiple servers thereby allows events started by different servers to be properly sequenced in time. When multiple server updates same data base , all updates are required to be time stamped in proper sequence. The Server Time Protocol feature is designed to provide the capability for multiple servers and Coupling Facilities to maintain time synchronization with each other Redundancy of timers allows to stay Sysplex if either of has planned /unplanned outage FICON Couple Data Sets Couple Data Sets STP Timer XCF XCF GRS GRS z/OS LPAR z/OS LPAR CF CF Server Time Protocol (STP) is a time synchronization architecture designed to provide the capability for multiple servers (CPCs) to maintain time synchronization with each other and to form a Coordinated Timing Network (CTN) To maintain time accuracy, the STP facility supports connectivity to an External Time Source (ETS) It is IBM’s License Internal Code (LIC) CDS CDS
- 22. Parallel Sysplex Continuous Availability With Parallel Sysplex cluster it is possible to construct a parallel processing environment single points of failure Because of the redundancy in the configuration, there is a significant reduction in the number of single points of failure. Ability to perform hardware and software maintenance and installations in a non- disruptive manner. Through data sharing and dynamic workload management, servers can be dynamically removed from or added to the cluster allowing installation and maintenance activities to be performed while the remaining systems continue to work. Capacity Parallel Sysplex environment can scale near linearly from 2 to 32 systems Dynamic Workload Balancing The entire Parallel Sysplex cluster can be viewed as a single logical resource to end and business applications. - Benefits
- 23. GDPS Geographically Dispersed Parallel Sysplex (GDPS) is an extension of Parallel Sysplex of mainframes located, potentially, in different cities or/and data centres. GDPS is an end to end application availability solution
- 24. Globally Dispersed Parallel Sysplex - GDPS • It is the ultimate disaster recovery and continuous availability solution for a multi-site enterprise • GDPS is combination of storage and Parallel Sysplex technology. • Automates Parallel Sysplex operation tasks and perform failure recovery from a single point of control. • Types of GDPS configurations • GDPS/PPRC based on synchronous data mirroring technology (PPRC) that can be used on mainframes 200 kilometres (120 mi) apart. • GDPS/XRC is an asynchronous Extended Remote Copy (XRC) technology with no restrictions on distance • GDPS/Global Mirror is based on asynchronous IBM Global Mirror technology with no restrictions on distance. • GDPS/active-active is a disaster recovery / continuous availability solution, based on two or more sites, separated by unlimited distances, running the same applications and having the same data to provide cross-site workload balancing.
- 25. GDPS ACTIVE/ACTIVE To achieve GDPS Active/Active configuration : • All critical data must be PPRCed and Hyper-swaped enabled • All critical CF structure must be duplexed • Application must be parallel sysplex enabled
- 26. GDPS/PPRC GDPS/PPRC, is metro area Continuous Availability (CA) and Disaster Recovery (DR) solution, based upon Multi-site Parallel (Sys)tem Com(plex) Synchronous disk replication It supports two configurations Active/Standby or single site workload Active/active or multi-site workload
- 27. Disks Site 1 Active Disks GDPS / PPRC Site 2 Warm PPRC / Metro Mirror • Even with the multi-path and RAID architecture within DASD subsystems the single copy of the data continues to be a single point of failure (SPOF). • A failure of a disk subsystem or even a single disk array failure can take down major applications, the system, or even the sysplex. • GDPS/PPRC is IBM disk replication technology to supplement removing SPOF
- 28. A Parallel Sysplex environment has been designed to reduce outages by replicating hardware, operating systems, and application components. In spite of this redundancy, having only one copy on the data is an exposure. GDPS Hyperswap If there is a problem writing or accessing the primary disk, then there is a need to swap I/O from the primary disks to the secondary disks. HyperSwap, a feature of GDPS, enhances the resilience by facilitating the immediate switching I/O operations from the primary to the secondary disks therefore providing near-continuous access to data
- 29. Secondary Disks Primary Disks PPRC / Metro Mirror GDPS Hyperswap GDPS Controlling System GDPS Controlling System Primary Site Secondary Site Hypersawap provides continuous availability of data by masking disk outages and automates switching between the two copies of the data without causing an application outage In real time. Failure HyperSwap K2K1 CDS
- 30. • In order for GDPS to operate, there must be a separate, isolated, z/OS system known as the Controlling system. • GDPS environments without a Controlling system are not supported. • IBM strongly recommends 2 Controlling systems are setup per Sysplex. • The idea is for one to act as a Primary and the other to be a Backup. GDPS controlling System PPRC / Metro Mirror GDPS Controlling System (K1) GDPS Controlling System(K2) K2 K1 Primary Site Secondary Site
- 31. PPRC / Metro Mirror GDPS controlling system : GDPS controlling system ? GDPS Controlling System (K1) GDPS Controlling System (K2) 1. Performs situation analysis (after the unplanned event) to determine the status of the production system and/or disks. 2. Drives automated recovery actions. The controlling system must be in same sysplex so it can see all the messages from systems in sysplex and communicate with them. K2K1 Primary Site Secondary Site CDSCDS z/OS LPAR (K1) XCF GRS CF z/OS LPAR XCF GRS CF (K2)
- 32. PPRC / Metro Mirror K2K1 Primary Site Secondary Site CDSCDS ALCS (K1) XCF GRS CF ALCS XCF GRS CF (K2) The availability of controlling system is fundamental to GDPS Why does a GDPS configuration need a controlling system ? GDPS controlling system is designed to survive a failure in the opposite site of where primary disks are . Primary disks are normally in Site1 and controlling system in Site2 is designed to survive if Site1 or the disks in Site1 fail.
- 33. Final view - Combining the jigsaw puzzle PPRC / Hyperswap K2 K1 Primary Site CDSCDS ALCS (K1) XCF GRS CF GDPS managed 40 KM Secondary Site ALCS XCF GRS CF (K2) CF links (Timer links) ADVA /DWDM ADVA /DWDM PPRC links , ISL Channels GDPS Site 1 TIBCO Site 2- Tibco Applications ESW Network
- 34. Conclusion Mainframe physical clustering (System complex /Sysplex) between dispersed data centres (GDPS) provides enterprise level disaster recovery, data sharing , parallel computing capability to share workload workload for high performance and high availability.
- 35. G D P S A N D S Y S T E M C O M P L E X N A J M I M A N S O O R A H M E D