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Problem Analysis andTroubleshooting
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Module Overview
Types of problems that affect IIS
How to identify them
What can cause them
How to troubleshoot themLots of hands on!
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Section 1: Common IIS-Related Problems
Application Crash
100% CPU Hang
0% CPU Hang
Performance IssuesMemory Leaks
Startup Problems
Access Issues
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Application Crash - How to Identify
Browser errors The connection with the server was reset
The remote procedure call failed
The RPC server is unavailable
ASP 0115 / HTTP 500
Event logs
IIS logs
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Application Crash - Possible Causes
Stack overflow
Stack corruption
Heap corruption
Divide by ZeroNull pointer dereference
Any other unhandled exception
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Application Crash - How to Troubleshoot
Review event logs
Review IIS logs for HTTP 500/ASP 0115 errors
Switch off all proactive recycling
Run ADPlus or DebugDiag in crash modeAnalyze memory dump in WinDBG
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100% CPU Hang - How to Identify
Browser shows only blank page or times out
Pages take a long time to load on browser
Check CPU usage in Task Manager or PerformanceMonitor
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100% CPU Hang - Possible Causes
Long loops
Infinite loops
Memory leaks
String manipulationGarbage collection
Insufficient hardware
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100% CPU Hang - How to Troubleshoot
Switch off all proactive recycling
Wait for problem to occur again
Gather Perfmon data
Run ADPlus or DebugDiag in hang modeAnalyze Perfmon data
Analyze memory dump in WinDBG
Perform live debug to identify the root cause, if required
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0% CPU Hang - How to Identify
Browser shows only blank page or times out
Create simple .htm, .asp, .aspx pages
Attempt to browse to each test page
Does process recover if load is removed?Easy to confuse with performance issues
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0% CPU Hang - Possible Causes
Serialization
Deadlocks
Orphaned critical sections or monitors
Microsoft Visual Basic (VB) RIM/UE issuesFailing COM/database/remoting calls
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0% CPU Hang - How to Troubleshoot
Switch off all proactive recycling
Enable process orphaning
Run DebugDiag or ADPlus in hang mode
Analyze memory dump in WinDBG
!locks
!critsec
!syncblk
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Performance Issues - How to Identify
Users report application is running slowly
Application appears to hang
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Performance Issues - Possible Causes
Too many to mention!
Serialization
Long COM/database/remoting calls
Insufficient hardware
Network congestion
Poor quality application code
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Performance Issues - How to Troubleshoot
Performance Monitor
Perfmon baseline logs
Stress testing tools
Application Center Test
WCAT
Log Parser
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Memory Leaks - How to Identify
Popup message stating "System out of virtual memoryRandom problems associated with a lack of virtualmemory
Degrading system performance and excessive swapping
Failed memory allocations
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Memory Leaks - Possible Causes
Application failing to free private memory or resourceallocations
Includes memory, user and gdi objects, handles, threads,etc.
Abnormal code paths which bypass free logic
Logic errors
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Memory Leaks - How to Troubleshoot
Performance MonitorPMON.EXE
DebugDiag (LeakTrack)
UMDH.exe
LeakDiag (Microsoft PSS Tool)
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Startup Problems - How to Identify
IIS fails to startIIS starts very slowly
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Startup Problems - Possible Causes
Large metabase filesPermissions
Corrupt/missing Machine Keys
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Access Issues - How to Identify
Users receive unexpected authentication promptsUsers get Access Denied messages
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Access Issues - Possible Causes
Incorrect authentication schemes configuredDC comms issues
Incorrect user or process identity permissions
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Access Issues - How to Troubleshoot
Network Monitor (NetMon)WFetch
AuthDiag
Log Parser
ASPNET_regiis
Permissions Verifier
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Section 2: Labs - Troubleshooting Scenarios
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Action Planning Exercise
Think about how youll apply the concepts and/or
practices youve learned when you return to your
workplace.
1.Summarize your action items
2.Questions for your trainer?3.Class discussion
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