Website Problem

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Website Problem by Mind Map: Website Problem

1. Site slow

1.1. Check Web server

1.1.1. CPU > 80% w3wp.exe is taking high CPU Check IIS log for long running pages Some other process is taking high CPU SQL Server and IIS on same box Some other app is taking CPU

1.1.2. High Memory Usage Certain .NET Process is consuming high memory If Virtual Memory significantly high compared to Working Set? Non .NET process consuming high memory Find out who is the vendor and ask for suport

1.1.3. High Disk usage Counter: Memory: Pages/Sec > 0 Check from task bar which process is taking most RAM Is Page file size is smaller than 1.5 times the RAM? Then set it 1.5 times the RAM

1.1.4. Counter: Requests in Application Queue > 0

1.1.5. Counter: Request Execution Time is > 20 sec You have some very slow pages or webservices that are consuming threads. Increase threads in processModel in machine.config if CPU consumption is low. If CPU consumption is high, then fix the code or get more servers and scale out

1.2. Check Database Server

1.2.1. Counter: SQL Server: Locks: Lock Timeout/Sec > 0 See Standard Reports: Top Transactions By Transaction Locks Count. Find the transaction that's blocking most of the transactions. Analyze the query and see why it takes so long.

1.2.2. Counter: SQL Server: Access Methods: Full Scans/Sec > 100 Bad queries, not hitting index. Find them from Standard Reports: Top Transactions by Average IO.

1.2.3. Counter: SQL Server: Access Methods: Table Lock Escalation/Sec > 20 Bad Queries, trying to read large amount of data and missing index. See from Standard Reports: Top Transactions by Average IO.

1.2.4. SQL Server: Memory Manager: Target Server Memory > Total Server Memory SQL Server needs more RAM. Add more RAM

1.2.5. SQL Server: Buffer Manager: Buffer Cache hit ratio < 85% SQL Server needs more RAM. Add more RAM You have queries that's reading data from random distant places from the database and SQL server has no clue what to cache

1.2.6. Memory: Pages/Sec > 4 You need to have at 40% RAM of the total database size. If your database size is 10 GB, have 4 GB RAM given to SQL Server You have some other process running on database server that's taking RAM. Find such process and uninstall them.

1.2.7. Processor: % Processor Time > 70% You have queries that's CPU intensive.

1.3. Check Firewall and Load Balancer

2. Site down

2.1. Check Web server

2.1.1. CPU over 90%

2.1.2. Check IIS Website stopped Starting Web site fails to start Application Pool Disabled Check Error in Event Log entries in System Category IIS Stopped Start IIS fails Check Event Log Entry

2.1.3. Check ASP.NET Performance Counters Error: Too many unhandled exceptions Bug in code, fix it! Implement custom error handler Too many Application Restarts Exception being thrown from background thread. High number of Requests in Application Queue Outbound calls are taking too long to finish. Lower down timeout or implement async pattern: Database calls are taking too long to complete. Optimize queries to execute faster.

2.2. Check Database Server

2.2.1. SQL Server service stopped

2.2.2. Database offline

2.2.3. SQL Server connection failing

2.2.4. SQL Server not executing query

2.3. Check Firewall and Load Balancer

3. Site sometimes comes

3.1. Check Web Server

3.1.1. High CPU

3.1.2. Check ASP.NET Perf Counters

3.2. Check Database Server

3.3. Check Firewall and Load Balancer

4. Randomly Requests fail