Too Deep Too Wide Using Soft Limits To
















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Too Deep & Too Wide Using Soft Limits To Avoid Hard Crashes NY/NJ Websphere MQ Family User Group IBM 590 Madison Ave, New York City Tuesday March 25, 2003 NY/NJ MQ Family Users’ Group T. Robert Wyatt, Vice President Bank Of America Differentiated Service Websphere MQ Support 1

Objectives • Demonstrate why the default queue depth and message length values pose a potential risk • Discuss one approach to mitigating that risk March 25, 2003 NY/NJ MQ Family Users’ Group 2

Scenario For Disaster Unrealistic requirements: “Need to be able to queue up an entire day’s worth of large XML messages” – Increase MAXDEPTH – Increase MAXMSGL March 25, 2003 NY/NJ MQ Family Users’ Group 3

Whoops! One day the channel goes down and the system performs exactly as designed: – Queues begin to fill up – Underlying filesystem fills – MQ begins to cut FDC files – MQ and possibly the OS are halted March 25, 2003 NY/NJ MQ Family Users’ Group 4

Recovery • Free up disk space any way possible – Move any diagnostic files – Delete non-essential files – Move older MQ logs if linear March 25, 2003 NY/NJ MQ Family Users’ Group 5

Recovery When (or if) QMgr becomes responsive again: • Stop all channels • RCDMQIMG if linear • Shut down the QMgr March 25, 2003 NY/NJ MQ Family Users’ Group 6

Recovery Restarting the QMgr: Delete files or add space – Clean up the file system – Remount the filesystem to larger disk and copy files Results in extended outage, high probability of client impact March 25, 2003 NY/NJ MQ Family Users’ Group 7

What Happened? 5, 000 x 4 mb messages = 20 GB 5 k x 4 mb persistent msgs > 40 GB Def Dead. Q 640, 000 x 4 mb = 2. 5 TB! When the capacity specified by soft limits exceeds the physical limits, then the soft limits do not exist. March 25, 2003 NY/NJ MQ Family Users’ Group 8

Hard Limits Application constrained only by limits of physical disk space – Failure is sudden – Failure may be catastrophic • Affects OS & co-resident apps – Slow manual recovery – High client impact March 25, 2003 NY/NJ MQ Family Users’ Group 9

Soft Limits Application constrained by MQ – System degrades gracefully – Failure isolated to specific apps within MQ – Recovery is automated – normal operation of MQ restores service – Minimal client impact March 25, 2003 NY/NJ MQ Family Users’ Group 10

Tuning Discipline Insure soft limits < physical limits – Reduce MAXDEPTH, MAXMSGL or both – Reduce settings on SYSTEM. DEF* as well as application queues – Reduce Dead. Q Settings! March 25, 2003 NY/NJ MQ Family Users’ Group 11

Tuning Discipline Disk Space Available* MAXMSGL MAXDEPTH DSA = MAXMSGL x MAXDEPTH = DSA / MAXMSGL = DSA / MAXDEPTH *Use ½ DSA for persistent msgs March 25, 2003 NY/NJ MQ Family Users’ Group 12

Tuning Discipline Know your messages! – Soft limits must be appropriate to the business to be enforceable – Standardize, preferably automate – Verify on each machine – No exceptions Too shallow? Too narrow? Buy more disk! March 25, 2003 NY/NJ MQ Family Users’ Group 13

Apply System Wide System-wide tuning parameters – Channel MAXMSGL – QMgr MAXMSGL – Max uncommitted messages – Log file size and extents – Use separate, preferably dedicated, filesystems for /var/mqm/qmgrs and /var/mqm/logs March 25, 2003 NY/NJ MQ Family Users’ Group 14

Resources IBM Websphere MQ Manuals http: //www-3. ibm. com/software/ts/mqseries/library/manualsa/ – Quick Beginnings Guide – System Administration Manual Support Pacs http: //www-3. ibm. com/software/integration/supportpacs/ – Capacity planning pacs – Performance reports March 25, 2003 NY/NJ MQ Family Users’ Group 15

Resources MQSeries. net: http: //www. mqseries. net Vienna List Server: http: //www-3. ibm. com/software/ts/mqseries/support/usergroups/listserver. html Download presentation: http: //www. t-rob. net/Downloads/2 Deep 2 Wide. ppt T. Rob: March 25, 2003 T. [email protected] net NY/NJ MQ Family Users’ Group 16
Deep Levels Deep Levels Deep Centers Deep Traps
Limits I Why limits II What are limits
LIMITS Why limits Methods for upper limits Desirable
Soft Tissue Injuries What are Soft Tissues Soft
Soft Skills Soft Skills Defined Soft skills refer
Soft Tissue Injuries What are Soft Tissues Soft
Deep asleep deep asleep Deep asleep it lies
LIMITS AND DERIVATIVES 2 3 Calculating Limits Using
WIDE AREA NETWORK WAN Wide Area Network merupakan
World Wide Web Prof Boeru Cristina World Wide
WIDE AWAKE HAND SURGERY WALANT WIDE AWAKE LOCAL
World Wide Web Consortium l World Wide Web
Wide Bandgap Semiconductors What is a wide bandgap
World Wide Web Consortium l World Wide Web
WWW World Wide Web Web World Wide Web
Wide Area Networks 1 Wide Area Networks WANs