Brief Intro to Mainframe and z/OS Administration By Luis F. Bustamante What is a mainframe? What is a mainframe? What is a mainframe? • Developed in 1950s • First mass-produced digital, all-transistorized, business computer that could be afforded by many businesses worldwide. • 1st general purpose computers • Designed with business applications in mind What is a mainframe? • Market dominated by IBM (90%+) – Made in Poughkeepsie, NY • Large-Scale computing • Large Enterprises • z Architecture (not x86 or x64) • Run various Operating Systems – z/OS – z/VM – Linux What is a mainframe? • Runs Multiple OS instances - LPAR • Serves tens of thousands of users • Manages petabytes of data • Very reliable • Used for Mission Critical Applications • Expensive (Cost Savings from Consolidation) • Scalable (After initial investment) • Highly secure • Large Data processing • Central data repository What is a mainframe? Typical Mainframe Workloads Batch Workload •Reports •Data consolidation •Billing •Account statements •Data Analytics Transactions • Quick interactions - Seconds, or fractions of seconds • Millions/billions transactions per day • Thousand of concurrent users • Require high availability • Examples: – Banks: ATM, Tellers, Financial Records – Airline reservations – Inventory control – Government: Tax processing, license issuance and management Transactions • Usually under CICS in z/OS: • CICS – Transaction Server – HTTP (REST, SOAP) – Web – Java – Cobol – C/C++ Roles in the Mainframe World Who uses mainframes? • 80% of fortune 500 companies • Banking • Finance • Health care • Insurance • Public utilities • Government What is z/OS? • Most common mainframe OS • EBCDIC (Extended Binary Coded Decimal Interchange Code) character set as opposed to ASCII • Implements POSIX compliant UNIX kernel to run UNIX type applications. • All kinds of workloads: – COBOL: usually legacy applications – Web services/interfaces. – C/C++, Java, PL/I • Highly Secure – RACF security server • Networking: – TCP/IP - Under Unix System Services – VTAM - legacy communications/networking protocol. Still widely used. • Not Suitable for Complex computational workloads Parallel Sysplex z/OS Clustering technology: • Up to 32 tightly coupled z/OS images • Add and remove dynamically • Distributed applications workload • Network Load Balancing and fail over. • 99.999% availability • Use of coupling facility – Shared communications channel – Resource management and serialization Common z/OS software setup • Security System: Usually RACF • Compilers • Relational Database: DB2 most common • Transaction processing facility: – CICS – IMS – WebSphere Application Server for z/OS • Sort Program • SDSF – System Display and Search Facility • Job Scheduling Software – Batch Management • WebSphere MQ for asynchronous application messaging • Other utilities. Networking on z/OS • IBM Communications Server for z/OS – VTAM /SNA Systems Network Architecture 1969 • IBM proprietary • Being phased out • Hierarchical Network Model. Mainframe Centric • 1 Mainframe owns terminal and other network devices • Not compatible with TCP/IP SNA has evolved, many applications still use it. Enterprise Externder (SNA over IP) allows it to operate over TCP/IP netwoks Networking on z/OS - SNA Networking on z/OS • IBM Communications Server for z/OS – TCP/IP and Networking Related Products • TN3270 • SMTP • BIND • FTP – VIPA and DVIPA – Sysplex Distributor (load balancing) – OSPF Networking on z/OS – TCP/IP in a sysplex Interacting with z/OS • TN3270 emulator – TSO/E – ISPF – z/OS Console • SSH – UNIX System Services Interacting with z/OS • TN3270 emulator – IBM’s terminal emulation software – Runs over telnet (Port 23) – Can be (it usually is) encrypted using SSL • TSO/E – Command line interface – Replaced by ISPF although TSO commands are still used for systems management and REXX scrips Interacting with z/OS • TSO/E Interacting with z/OS • ISPF – Panel driven – Access to multiple utilities and programs for dataset manipulation – ISPF Editor – for editing and viewing datasets Interacting with z/OS • ISPF Interacting with z/OS • z/OS console – Used to interact directly with the operating system • Startup • Shutdown • Task management – There are better ways • Reply to system and application messages – Displays ALL operating system messages and other system related software. – Used mostly by operations personnel Interacting with z/OS • JCL – Job Control Language – In z/OS everything runs as a Job, including users – Used to be entered using punch cards – Used for batch processing – Specifies runtime options – Specifies input and output datasets Interacting with z/OS • JCL – Job Control Language: Interacting with z/OS • SDSF – Job/process management – Operating System log – Job Output Display – Allows for console command entry Interacting with z/OS • SDSF z/OS and UNIX comparison z/OS and UNIX comparison z/OS and UNIX comparison z/OS and UNIX comparison • NO root user – User access is managed according to roles, even under Unix System Services • NO hierarchical file system - z/OS uses catalogs to store dataset information – Master Catalog: Think of it as the root of the file system. It points to multiple user catalogs. UNIX within z/OS • A.K.A UNIX System Services or z/OS UNIX • POSIX and XPG4 compliant • Java • TCP/IP • Other ported utilities • Accessed via: – OMVS: Shell like interface – ISPF Shell: Panel Driven Interface – SSH: tcsh shell interface DEMO YAY!!!! Additional reading Introduction to the New Mainframe series: http//:redbooks.ibm.com Additional reading IBM’s Master the Mainframe Contest: http://www.ibm.com/developerworks/university/students/contests/mainfr ame/details.html IBM’s z/OS Basics infocenter: http://publib.boulder.ibm.com/infocenter/zos/basics/index.jsp IBM’s Academic Initiative Website: http://www-03.ibm.com/ibm/university/academic/pub/page/systemz .