• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
AASites_IMS_Repl -  IMS UG 9.11.13 eMeeting
 

AASites_IMS_Repl - IMS UG 9.11.13 eMeeting

on

  • 290 views

 

Statistics

Views

Total Views
290
Views on SlideShare
290
Embed Views
0

Actions

Likes
0
Downloads
4
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    AASites_IMS_Repl -  IMS UG 9.11.13 eMeeting AASites_IMS_Repl - IMS UG 9.11.13 eMeeting Presentation Transcript

    • IBM GDPS Active-Active and IMS Replication 1 IBM GDPS Active-Active and IMS Replication Greg Vance IMS Development, STSM gvance@us.ibm.com
    • Availability. References in this presentation to IBM products, programs, or services do not imply that they will be available in all countries in which IBM operates. Acknowledgements and Disclaimers The workshops, sessions and materials have been prepared by IBM or the session speakers and reflect their own views. They are provided for informational purposes only, and are neither intended to, nor shall have the effect of being, legal or other guidance or advice to any participant. While efforts were made to verify the completeness and accuracy of the information contained in this presentation, it is provided AS-IS without warranty of any kind, express or implied. IBM shall not be responsible for any damages arising out of the use of, or otherwise related to, this presentation or any other materials. Nothing contained in this presentation is intended to, nor shall have the effect of, creating any warranties or representations from IBM or its suppliers or licensors, or altering the terms and conditions of the applicable license agreement governing the use of IBM software. All customer examples described are presented as illustrations of how those customers have used IBM products and the results they may have achieved. Actual environmental costs and performance characteristics may vary by customer. Nothing contained in these materials is intended to, nor shall have the effect of, stating or implying that any activities undertaken by you will result in any specific sales, revenue growth or other results. 2 © Copyright IBM Corporation 2013. All rights reserved. – U.S. Government Users Restricted Rights - Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. IBM, the IBM logo, ibm.com, IMS, DB2, CICS and WebSphere MQ are trademarks or registered trademarks of International Business Machines Corporation in the United States, other countries, or both. If these and other IBM trademarked terms are marked on their first occurrence in this information with a trademark symbol (® or ™), these symbols indicate U.S. registered or common law trademarks owned by IBM at the time this information was published. Such trademarks may also be registered or common law trademarks in other countries. A current list of IBM trademarks is available on the Web at “Copyright and trademark information” at www.ibm.com/legal/copytrade.shtml Other company, product, or service names may be trademarks or service marks of others.
    • Agenda • Level set • Concepts • Sample Scenarios 3 • IMS Replication • Summary
    • Suite of GDPS service products to meet various business requirements for availability and disaster recovery Continuous Availability of Data within a Data Center GDPS/PPRC HM RPO=0 [RTO secs] for disk only Disaster Recovery Extended Distance GDPS/GM & GDPS/XRC RPO secs, RTO<1h CA Regionally and Disaster Recovery Extended Distance GDPS/MGM & GDPS/MzGM RPO=0,RTO mins/<1h & RPO secs, RTO<1h Continuous Availability with DR within Metropolitan Region GDPS/PPRC RPO=0 RTO mins / RTO<1h (<20km) (>20km) 4 Single Data Center Applications remain active Continuous access to data in the event of a storage outage Two Data Centers Rapid Systems D/R w/ “seconds” of data loss Disaster Recovery for out of region interruptions Three Data Centers High availability for site disasters Disaster recovery for regional disasters RPO – recovery point objective RTO – recovery time objective Two Data Centers Systems remain active Multi-site workloads can withstand site and/or storage failures
    • How Much Interruption can your Business Tolerate? Ensuring Business Continuity: • Disaster Recovery – Restore business after an unplanned outage • High-Availability – Meet Service Availability objectives e.g., 99.9% availability or 8.8 hours of down-time a year • Continuous Availability – No downtime (planned or not) Standby Active/Active 5 Global Enterprises that operate across time- zones no longer have any ‘off-hours’ window. Continuous Availability is required. What is the cost of 1 hour of downtime during core business hours? Active/Active
    • • Shift focus from failover model to near-continuous availability model (RTO near zero) • Access data from any site (unlimited distance between sites) • Multi-sysplex, multi-platform solution – “Recover my business rather than my platform technology” • Ensure successful recovery via automated processes (similar to GDPS technology today) – Can be handled by less-skilled operators Evolving customer requirements 6 – Can be handled by less-skilled operators • Provide workload distribution between sites (route around failed sites, dynamically select sites based on ability of site to handle additional workload) • Provide application level granularity – Some workloads may require immediate access from every site, other workloads may only need to update other sites every 24 hours (less critical data) – Current solutions employ an all-or-nothing approach (complete disk mirroring, requiring extra network capacity)
    • From High Availability to Continuous Availability • GDPS/Active-Active is for mission critical workloads that GDPS/PPRC GDPS/XRC or GDPS/GM GDPS/Active-Active Failover Model Failover Model Near CA model Recovery Time ≈ 2 min Recovery Time < 1 hour Recovery time < 1 minute Distance < 20 km Unlimited distance Unlimited distance 7 • GDPS/Active-Active is for mission critical workloads that have stringent recovery objectives that can not be achieved using existing GDPS solutions – RTO approaching zero, measured in seconds for unplanned outages – RPO approaching zero, measured in seconds for unplanned outages – Non-disruptive site switch of workloads for planned outages – At any distance • Active-Active is NOT intended to substitute for local availability solution such as Parallel Sysplex
    • Agenda • Level set • Concepts • Sample Scenarios 8 • IMS Replication • Summary
    • Terminology • Active/Active Sites – This is the overall concept of the shift from a failover model to a continuous availability model • GDPS active/active continuous availability – This is the formal name of the overall solution under which IBM will deliver capabilities over a period of time 9 – While IBM currently provides the GDPS active-standby configuration, our future road map includes additional configurations that can lead to full active-active function • GDPS/Active-Active – The name of the GDPS product which provides, along with the other products that make up the solution, the capabilities mentioned in this presentation such as workload, replication and routing management and so on. This can be shortened to GDPS/A-A
    • Workload Distributor Active/Active Sites concept Transactions • Two or more sites, separated by unlimited distances, running the same applications and having the same data to provide: – Cross-site Workload Balancing – Continuous Availability – Disaster Recovery • Data at geographically dispersed sites kept in sync via s/w 10 Distributor Replication sites kept in sync via s/w replication Monitoring spans the sites and now becomes an essential element of the solution for site health checks, performance tuning, etc Workloads are managed by a client and routed to one of many replicas, depending upon workload weight and latency constraints; extends workload balancing to SYSPLEXs across multiple sites
    • Active/Active Sites Configurations • Configurations 1. Active/Standby – GA date 30th June 2011 2. Active/Query – statement of direction 3. Active/Active – intended direction • A configuration is specified on a workload basis 11 • A configuration is specified on a workload basis • A workload is the aggregation of these components – Software: user written applications (eg: COBOL programs) and the middleware run time environment (eg: CICS regions, InfoSphere Replication Server instances and DB2 subsystems) – Data: related set of objects that must preserve transactional consistency and optionally referential integrity constraints (eg: DB2 Tables, IMS Databases) – Network connectivity: one or more TCP/IP addresses & ports (eg: 10.10.10.1:80)
    • Application A, B activeWordload A, B standby Active/Standby configuration BBAA Static Routing Automatic Failover Workload A, B active Transactions 12 Workload Distributor Replication IMS DB2 IMSDB2<< >> << queued >> This is a fundamental paradigm shift from a failover model to a continuous availability model site2site1
    • Appl B (grey) is in active/query configuration • using same data as Appl A but read only • active to both site1 & site2, but favor site1 • Appl B query routing according to Appl A latency policy Transactions Active/Query configuration (SOD) BB B B B AAA Workload Distributor Appl A (gold) is in active/standby configuration • performing updates in active site [site2] 13 Replication M IMS DB2 IMSDB2 <<<< site2site1 <<<< [A] latency>5; as “max latency” policy has been exceeded. route all queries to site2 [A] latency<3; as latency is less than “reset latency” policy, route more queries to site1 [A] latency=2; as latency is less than “max latency”, follow policy to skew queries to site1 Read-only or query transactions to be routed to both sites, while update transactions are routed only to the active site All statements regarding IBM's future direction and intent are subject to change or withdrawal without notice, and represent goals and objectives only.
    • What S/W makes up a GDPS/Active-Active environment? • GDPS/Active-Active • IBM Tivoli NetView for z/OS – IBM Tivoli NetView for z/OS Enterprise Management Agent (NetView agent) • IBM Tivoli Monitoring • System Automation for z/OS • Multi-site Workload Lifeline for z/OS (SA z/OS) 14 • Multi-site Workload Lifeline for z/OS (SA z/OS) • Middleware – DB2, IMS, CICS… • Replication Software – IBM InfoSphere Replication Server for z/OS (DB2) – IBM InfoSphere IMS Replication for z/OS • Optionally the Tivoli OMEGAMON XE suite of monitoring products Integration of a number of software products
    • GDPS/A-A configuration Backup Controller NetView Backup LLAdvisor Secondary TEMA LB 2nd Tier Sysplex Distrib LB 2nd Tier Sysplex Distrib AAC2LB 1st Tier CSM Network GDPS Web InterfaceTEP Interface Primary Controller NetView Master LLAdvisor Primary TEMA AAC1 15 A1 Production 1 A1 Production 2 LLAgent LLAgent MQ / TCPIP MQ / TCPIP Workload 1 Active Workload 3 Active Workload 1 Active Workload 3 Active DB2 Rep IMS Rep DB2 Rep IMS Rep CICS/DB2 Appl IMS Appl CICS/DB2 Appl IMS Appl A2 Production 2 A2 Production 1 LLAgent LLAgent MQ / TCPIP MQ / TCPIP Workload 1 Standby Workload 3 Standby Workload 1 Standby Workload 3 Standby DB2 Rep IMS Rep DB2 Rep IMS Rep CICS/DB2 Appl IMS Appl CICS/DB2 Appl IMS Appl TEMA Site 1 Site 2DB2 IMS DB2 IMS A1P2A1P1 A2P1A2P2 S/W Replication TEMA
    • • Automation code is an extension on many of the techniques tried and tested in other GDPS products and with many client environments for management of their mainframe CA & DR requirements • Control code only runs on Controller systems • Workload management - start/stop components of a workload in a given Sysplex • Replication management - start/stop replication for a given workload between sites GDPS/Active-Active (the product) 16 between sites • Routing management - start/stop routing of transactions to a site • System and Server management - STOP (graceful shutdown) of a system, LOAD, RESET, ACTIVATE, DEACTIVATE the LPAR for a system, and capacity on demand actions such as CBU/OOCoD • Monitoring the environment and alerting for unexpected situations • Planned/Unplanned situation management and control - planned or unplanned site or workload switches; automatic actions such as automatic workload switch (policy dependent) • Powerful scripting capability for complex/compound scenario automation
    • Agenda • Level set • Concepts • Sample Scenarios 17 • IMS Replication • Summary
    • AA Controller [AAC1] Primary AA Controller [AAC2] Backup Network LB 2nd Tier Sysplex Distrib LB 1st Tier CSM LB 2nd Tier Sysplex Distrib Sample scenario – all workloads active in one site SASP-compliant Routers Routing for WKLD 1, 2 & 3 18 Site 1 Site 2 A1 Prod-sys [A1P1] wkld-1 active wkld-2 active wkld-3 active A1 Prod-sys [A1P2] wkld-1 active wkld-3 active A2 Prod-sys [A2P1] wkld-1 standby wkld-2 standby wkld-3 standby A2 Prod-sys [A2P2] wkld-1 standby wkld-3 standby S/W ReplicationDB2 DB2 IMS DB2 DB2 IMS Sysplex-A1 [AAPLEX1] Sysplex-A2 [AAPLEX2]
    • AA Controller [AAC1] Primary AA Controller [AAC2] Backup Sample scenario – both sites active for individual workloads Network LB 2nd Tier Sysplex Distrib LB 1st Tier CSM LB 2nd Tier Sysplex Distrib SASP-compliant Routers Routing for WKLD 1 & 3 Routing for WKLD 2 19 Site 1 Site 2 A1 Prod-sys [A1P1] wkld1 active wkld2 standby wkld3 active A1 Prod-sys [A1P2] wkld1 active wkld3 active A2 Prod-sys [A2P1] wkld1 standby wkld2 active wkld3 standby A2 Prod-sys [A2P2] wkld1 standby wkld3 standby Sysplex-A1 [AAPLEX1] Sysplex-A2 [AAPLEX2] S/W ReplicationDB2 DB2 IMS DB2 DB2 IMS
    • LB 1st Tier CSM LB 2nd Tier Sysplex Distrib LB 2nd Tier Sysplex Distrib Planned workload/site switch TEP Interface GDPS Web Interface AAC1 primary AAC2 backup STOP ROUTING START ROUTING all data has been drained continue [click here] Initiate [click here] SS Y Network 20 <<<< >>>> CICS/DB2 Appl [DB2 Rep] WKLD2 WKLD3 AAPLEX1 A1P1 CICS/DB2 Appl DB2 Rep WKLD2 A1P2 WKLD1 WKLD1 standby standbyactive active CICS/DB2 Appl WKLD1 CICS/DB2 Appl WKLD1 WKLD2 [DB2 Rep]DB2 Rep WKLD2 WKLD3 AAPLEX2 A2P2 A2P1 DB2DB2IMS DB2 DB2 IMS >> Site1 Site2 Note: multiple workloads and needed infrastructure resources are not shown for clarity sake >> << active activestandby standby
    • LB 2nd Tier Sysplex Distrib LB 2nd Tier Sysplex Distrib LB 1st Tier CSM Unplanned site failure TEP Interface GDPS Web Interface AAC1 primary AAC2 backup STOP ROUTING START ROUTING Network 21 <<<< CICS/DB2 Appl WKLD1 [DB2 Rep] WKLD2 WKLD3 AAPLEX1 A1P1 CICS/DB2 Appl WKLD1 DB2 Rep WKLD2 A1P2 DB2DB2IMS CICS/DB2 Appl WKLD1 CICS/DB2 Appl WKLD1 WKLD2 [DB2 Rep]DB2 Rep WKLD2 WKLD3 A2P2 A2P1 active active DB2 DB2 IMS Site2 Failure Detection Interval = 60 sec SITE_FAILURE = Automatic AAPLEX2 Site1 Note: multiple workloads and needed infrastructure resources are not shown for clarity sake Automatic switch << active activestandby standby >> queued
    • 20 15 60 0 15 30 45 60 GDPS/A-A planned site switch GDPS/A-A unplanned site switch GDPS/XRC, GDPS/GM site failover SwitchTime(secs) 0 60 120 SiteFailoverTime(mins) GDPS/A-A – testing results* min sec sec 120 min 22 * IBM laboratory results; actual results may vary • Configuration – 9 * CICS/DB2 and 1 * IMS workload – Distance between sites 300 miles (≈500 km) – Site failure detection interval is 60 seconds • Planned site switch – Operations initiated switch of the workloads in a site to the other site took 20 seconds – Current GDPS and disk replication will take ≈1-2 hours • Unplanned site switch – Automatic switch of failed site workloads to the surviving site took 15 seconds – Current GDPS & disk replication will take about ≈1 hour
    • Agenda • Level set • Concepts • Sample Scenarios 23 • IMS Replication • Summary
    • IMS Software-Based Data Mirroring InfoSphere IMS Replication • Unidirectional Replication of IMS data – Subscription Level Replication • Transaction consistency • All or nothing at DB level • Basic replication monitoring • TCP/IP for data transmission • IMS “Capture” – DB/TM, DBCTL, Batch DL/I, FDBR IMS InfoSphere IMS Replication IMS 24 – DB/TM, DBCTL, Batch DL/I, FDBR – Capture x’99’ log records • Increase in log volume due to change data capture records • IMS “Apply” – Uses IMS Database Resource Adapter interface – Parallel Apply – Conflicts will be detected • Manual resolution will be required • Classic Data Architect – Administration (some administration can be done via z/OS console commands) – Basic replication monitoring IMS
    • Classic Data Architect Target IMS Databases Replication Metadata Administration Administration IMSIMS Source IMS Databases Replication Metadata Bookmark Database IMS Replication Architecture 25 SOURCE SERVER TARGET SERVER TCP/IP IMS Logs IMS DRA Interface Administration One Session Per Subscription Log Read/ Merge UOR Capture UOR Analysis IMS UOR Apply
    • IMS IMS Source IMS Databases Multi-Target Configuration IMS IMS Source Server Target Server 26 IMS Logs IMS IMS • Multiple Subscriptions • Each subscription associated with one of the target servers • Single server sends updates to appropriate target Server Target Server
    • IMS IMS Sample Two-way Replication Configuration IMS Source Server Target Server Workload A Update/Query Workload A Query 27 IMS IMS Target Server IMS Source Server Query Workload B Query Workload B Update/Query
    • Source Server Details Replication Metadata IMS IMS TM / DB Partner Product Exit IMS Logs IMS Logs TCP/IP •User exits to notify server of new IMS instance •Merge Waits for Batch DL/I to complete 28 Change Stream Ordering SOURCE SERVERRECON IMS Logger Exit BATCH DL/I IMS DBCTL Partner Product Exit Capture Services IMS Logs Log Info Source IMS Databases TCP/IP TCP/IP DL/I to complete •Idle IMS regions can slow processing
    • Target Server Details Writer Services Staged Unit-of-Recovery Data IMS DRA thread Writer Apply Service Change Messages 29 TARGET SERVER Dependency Analysis Writer Services Service • Parallelism based on dependency analysis within a subscription • Database and root key used for analysis
    • Classic Data Architect – Replication Management 30
    • Classic Data Architect - Monitoring Throughput 31
    • Classic Data Architect - Monitoring Latency 32
    • Adaptive Apply • Adaptive apply error handling is the default behavior – Can be set to standard apply, which does not tolerate conflicts • If a conflict is detected, the action will be to ignore update 33 • If a conflict is detected, the action will be to ignore update • Conflicts are: – Before image mismatch – Unable to locate segment to process update • All conflicts are logged in the event log • Manual resolution will be required
    • Current Restrictions • All segments for a DB must have change capture logging enabled and will be replicated – Must augment the DBD with the EXIT=(…,LOG) specification – IMS change capture restrictions • DEDB FLD calls not supported 34 • Subset Pointers not managed • ISRT HERE -> ISRT FIRST • Workload Restrictions – All logically related DBs must be in the same subscription – Workload with logically related DBs will be serialized – UORs with unkeyed or non-unique keyed segments will be serialized • External load of target DB – Must be a static image copy
    • Performance considerations • Transactional consistency vs. Parallelism – All updates for a given UR processed as a single transaction during apply – All transactions involving the same ‘resource’ will be serially processed in commit order – Running transactions in parallel can have application consistency implications 35 implications • Increase in log data • Multiple source IMSs to 1 Apply Target implications • Internally achieved 53K updates per second – ~116,000 updates per second when deploying two apply servers – sustained <2sec latency – your results may vary
    • Agenda • Level set • Concepts • Sample Scenarios 36 • IMS Replication • Summary
    • Replication Summary • Asynchronous Replication – Allows for unlimited distance support • Low Latency through parallelism – Allows for almost immediate data availability and low RTO 37 – Allows for almost immediate data availability and low RTO • Transaction Consistency – Access with integrity on target system and low RTO • Subscription independence – Switch can be at a workload level vs. system level
    • GDPS Active/Active Summary • Manages availability at a workload level • Provides a central point of monitoring & control • Manages replication between sites • Provides the ability to perform a controlled workload site switch • Provides near-continuous data and systems availability and helps simplify disaster recovery 38 availability and helps simplify disaster recovery with an automated, customized solution • Reduces recovery time and recovery point objectives – measured in seconds • Facilitates regulatory compliance management with a more effective business continuity plan • Simplifies system resource management GDPS/Active-Active is the next generation of GDPS
    • There are multiple GDPS service products under the GDPS solution umbrella to meet various customer requirements for Availability and Disaster Recovery Continuous Availability of Data within a Data Center GDPS/PPRC HM RPO=0 [RTO secs] Disaster Recovery Extended Distance GDPS/GM & GDPS/XRC RPO secs, RTO<1h CA Regionally and Disaster Recovery Extended Distance GDPS/MGM & GDPS/MzGM RPO=0,RTO mins/<1h RPO secs, RTO<1h CA, DR, & Cross- site Workload Balancing Extended Distance GDPS/Active-Active RPO secs, RTO secs Continuous Availability with DR within Metropolitan Region GDPS/PPRC RPO=0 RTO mins / RTO<1h 39 Single Data Center Applications remain active Continuous access to data in the event of a storage outage [RTO secs] for disk only Two Data Centers Rapid Systems D/R w/ “seconds” of data loss Disaster Recovery for out of region interruptions Three Data Centers High availability for site disasters Disaster recovery for regional disasters & RPO secs, RTO<1h Two Active Data Centers Automatic workload switch in seconds; seconds of data loss RPO – recovery point objective RTO – recovery time objective RTO mins / RTO<1h (<20km) (>20km) Two Data Centers Systems remain active Multi-site workloads can withstand site and/or storage failures
    • Thank You 40
    • The following are trademarks of the International Business Machines Corporation in the United States and/or other countries. The following are trademarks or registered trademarks of other companies. * Registered trademarks of IBM Corporation IBM* IBM (logo)* Ibm.com* AIX* DB2* DS6000 DS8000 Dynamic Infrastructure* Adobe, the Adobe logo, PostScript, and the PostScript logo are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States, and/or other countries. Cell Broadband Engine is a trademark of Sony Computer Entertainment, Inc. in the United States, other countries, or both and is used under license there from. ESCON* FlashCopy* GDPS* HyperSwap IBM* IBM logo* Parallel Sysplex* POWER5 Redbooks* Sysplex Timer* System p* System z* Tivoli* z/OS* z/VM* Trademarks 41 * All other products may be trademarks or registered trademarks of their respective companies. Notes: Performance is in Internal Throughput Rate (ITR) ratio based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput that any user will experience will vary depending upon considerations such as the amount of multiprogramming in the user's job stream, the I/O configuration, the storage configuration, and the workload processed. Therefore, no assurance can be given that an individual user will achieve throughput improvements equivalent to the performance ratios stated here. IBM hardware products are manufactured from new parts, or new and serviceable used parts. Regardless, our warranty terms apply. All customer examples cited or described in this presentation are presented as illustrations of the manner in which some customers have used IBM products and the results they may have achieved. Actual environmental costs and performance characteristics will vary depending on individual customer configurations and conditions. This publication was produced in the United States. IBM may not offer the products, services or features discussed in this document in other countries, and the information may be subject to change without notice. Consult your local IBM business contact for information on the product or services available in your area. All statements regarding IBM's future direction and intent are subject to change or withdrawal without notice, and represent goals and objectives only. Information about non-IBM products is obtained from the manufacturers of those products or their published announcements. IBM has not tested those products and cannot confirm the performance, compatibility, or any other claims related to non-IBM products. Questions on the capabilities of non-IBM products should be addressed to the suppliers of those products. Prices subject to change without notice. Contact your IBM representative or Business Partner for the most current pricing in your geography. Cell Broadband Engine is a trademark of Sony Computer Entertainment, Inc. in the United States, other countries, or both and is used under license there from. Java and all Java-based trademarks are trademarks of Sun Microsystems, Inc. in the United States, other countries, or both. Microsoft, Windows, Windows NT, and the Windows logo are trademarks of Microsoft Corporation in the United States, other countries, or both. InfiniBand is a trademark and service mark of the InfiniBand Trade Association. Intel, Intel logo, Intel Inside, Intel Inside logo, Intel Centrino, Intel Centrino logo, Celeron, Intel Xeon, Intel SpeedStep, Itanium, and Pentium are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries. UNIX is a registered trademark of The Open Group in the United States and other countries. Linux is a registered trademark of Linus Torvalds in the United States, other countries, or both. ITIL is a registered trademark, and a registered community trademark of the Office of Government Commerce, and is registered in the U.S. Patent and Trademark Office. IT Infrastructure Library is a registered trademark of the Central Computer and Telecommunications Agency, which is now part of the Office of Government Commerce.