Transcript Validate That System Is Actually I/O Bound

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
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
System Navigator
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
Physical Reads
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
Access Path Rebuilds
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
Query Optimizer
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
Copy File Operations
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
Opens and Closes
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
Workload Navigator
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
Operating System Program
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
Application Program
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
Database File
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
Procedure Name
Q&A
Questions & Answers
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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!