improving efficiency of i/o bound systems more memory, better caching newer and faster disk drives...
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Improving Efficiency of I/O Bound Systems
Improving Efficiency of I/O Bound Systems
• More Memory, Better Caching• Newer and Faster Disk Drives• Set Object Access (SETOBJACC)
• Reorganize (RGZPFM) w/ Key File• Applications Requesting Less I/O
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Validate That System Is Actually I/O Bound
Validate That System Is Actually I/O Bound
• CPU Is Under Utilized!• Poor Interactive Response Time• Long Running Batch Jobs• High Memory Faulting• High Disk Actuator Arm Activity
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System Navigator
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Identify Files With Highest Physical I/O
Identify Files With Highest Physical I/O
• Set Object Access (SETOBJACC)• Better Blocking of Data• Internal Program Arrays• Purge Old Transaction History• Build Better Logical Files• Stop Full Table Scans
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Tune Database, Avoid Access Path Rebuilds
Tune Database, Avoid Access Path Rebuilds
• Identify Files Most Heavily Hit• Avoid SQL Full Table Scans• Limit Access Path Rebuilds• Small Tables OK, Large – Not!• Basic Database Administration• Dramatic Reduction in I/O Needs
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Identify Specific Culprits & New Logicals
Identify Specific Culprits & New Logicals
• Batch, Interactive or ODBC• Specific Jobs and Users• Actual I/O by File and Program• Skipped Records v.s. Selected• New Permanent Logical Files• Delete Old Ones Not Being Used
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Query Optimizer
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Avoid Simple CL Programming Issues
Avoid Simple CL Programming Issues
• Never CPYF w/ SELECT/OMIT• Use OPNQRYF and CPYFRMQRYF• Easy Technique, Limit I/O Needs• Use RPG, COBOL, SQL, etc..• Prevent I/O From Full Table Scans• Work File in QTEMP w/ Keys
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Prevent Unnecessary Opens and Closes
Prevent Unnecessary Opens and Closes
• Leave Files Open, Reuse Paths• Simply Move Record Pointer• Files Left Open All Day, GOOD!• Better Than Constant Opens/Closes• Share Open Data Paths Correctly• RETRN v.s SETON LR
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Identify Specific Job and User Culprits
Identify Specific Job and User Culprits
• Focus on 80/20 Rule• Get Hardware & Software In Sync• Database Tuning• System Management Changes• Application Optimization Changes• Hardware Upgrades
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Workload Navigator
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Find Specific Operating System Functions
Find Specific Operating System Functions
• QQQIMPLE and QSQROUTE• QDBGETSQ v.s. QDBGETKY• Trace Back to Application Program• Simple Code Changes, No Rewrite• Weigh Cost v.s. Benefit• Find Quick, Easy Code Fixes
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Analyze Application Program Efficiency
Analyze Application Program Efficiency
• 75% Finding Data, Inefficient!• Less Time Searching, Sorting• Free Up I/O Bottleneck• Allow CPU to be Used Effectively• Consume Resource w/ Updates• Process Only Selected Transactions
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Identify Specific Database File I/O Counts
Identify Specific Database File I/O Counts
• Compare Reads to Writes/Updates• Less Time Reading via Indexes• Reduce I/O to Only Selected Records• Avoid Full Table Scans• Prevent Access Path Rebuilds• Use Proper Keyed File Sequences
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Find Procedures within Code Causing Issues
Find Procedures within Code Causing Issues
• Rewrite Just Specific Procedure• Summarize Data More Efficiently• Use Pre-Summarized Data Tables• Avoid Constant Re-Processing• Extract Data Once, Reuse Many• Process Only “OPEN” Transactions
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Q&A
To receive MB Software’s FREE performance evaluation:
1. Register at http://www.mb-software.com 2. Download and install software on AS/400 or iSeries 3. Call (800) 713-5034 to schedule your free performance review session
What To Expect:
After allowing performance data to accumulate for one full business day, you will log into a secure area of MB Software’s web site. We will then have a conference call to discuss our findings and how you can gain performance improvements with your existing applications. It’s that easy!
Questions & Answers