Threshold of Performance counter values to be considered as ideal

Performance monitor has a set of counters that can be monitored over a given period of time to see if the Windows server that is hosting the Sql Server is in good health.

A general question for a SQL Server DBA while monitoring counters in performance monitor is 'What is the threshold for each of the counters that can be considered as alarm bells for further investigation?'

The below table summarizes the counters and their ideal values. It was given to me by a Microsoft Engineer who works at our client place. All the values have been put together by his team at Microsoft.

The below should be a very good starting point for a DBA to either zoom in or rule out OS as the culprit.

PerformanceObject	Counter	Observed value	Threshold
Memory	Available MBytes		<10mb>
Memory	Cache Bytes
Memory	Commit Limit
Memory	Committed Bytes		> Physical Bytes is bad
Memory	Free System Page Table Entries		<5,000>very bad; <7,000>
Memory	Page Faults/sec		<>
Memory	Pages/sec		>2500/s bad for modern servers; less for older servers
Memory	Pool NonPaged Bytes		32-bit: 100MB-260MB; 64-bit: 1GB-128GB (depends on total physical RAM; is it close to being consumed)
Memory	Pool Paged Bytes		32-bit: 120MB-480MB; 64-bit: 1GB-128GB (depends on total physical RAM; is it close to being consumed)
Memory	System Cache Resident Bytes
Network Interface	Bytes total/sec	*	look for descending numbers to indicate network problems (kk)
Paging File	% Usage	*	>70% is a cause for concern
Paging File	% Usage Peak	*
PhysicalDisk/LogicalDisk	% Disk Time	*	>85% (consider spindle count)
PhysicalDisk/LogicalDisk	% Free Space	*	10-30%
PhysicalDisk/LogicalDisk	% Idle Time	*
PhysicalDisk/LogicalDisk	Avg. Disk Bytes/Read	*
PhysicalDisk/LogicalDisk	Avg. Disk Bytes/Transfer	*	Avg. I/O size; theoretical ~90-100MB/s sequential; reality significantly less
PhysicalDisk/LogicalDisk	Avg. Disk Bytes/Write	*
PhysicalDisk/LogicalDisk	Avg. Disk Queue Length	*	1.5 x # of spindles
PhysicalDisk/LogicalDisk	Avg. Disk Read Queue Length	*	1.5 x # of spindles
PhysicalDisk/LogicalDisk	Avg. Disk sec/Read	*	Disk Latency > 50ms POOR
PhysicalDisk/LogicalDisk	Avg. Disk sec/Transfer	*	Disk Latency > 50ms POOR
PhysicalDisk/LogicalDisk	Avg. Disk sec/Write	*	Disk Latency > 50ms POOR
PhysicalDisk/LogicalDisk	Avg. Disk Queue/sec	*	Disk Latency
PhysicalDisk/LogicalDisk	Avg. Disk Write Queue Length	*	1.5 x # of spindles
PhysicalDisk/LogicalDisk	Current Disk Queue Length	*	1.5 x # of spindles
PhysicalDisk/LogicalDisk	Disk Bytes/sec	*
PhysicalDisk/LogicalDisk	Disk Read Bytes/sec	*
PhysicalDisk/LogicalDisk	Disk Write Bytes/sec	*
PhysicalDisk/LogicalDisk	Disk Reads/sec	*	}~150 (for random)
PhysicalDisk/LogicalDisk	Disk Transfers/sec	*	}
PhysicalDisk/LogicalDisk	Disk Writes/sec	*	}
PhysicalDisk/LogicalDisk	Split IO/sec	*	Fewer the better
Process	% Processor Time	_Total,
Process	Page Faults/sec	_Total,	<>
Process	Handle Count	_Total,
Process	IO Data Operations/sec	_Total,
Process	IO Other Operations/sec	_Total,
Process	Private Bytes	_Total,
Process	Virtual Bytes	_Total,
Process	Working Set	_Total,
Processor	% Idle
Processor	% Privileged Time
Processor	% Processor Time
Processor	% User		User+Priv>80% CPU bottleneck
Processor	Interrupts/sec
System	Context Switches/sec		5,000/s x # of CPUs; somewhat flexible if other CPU-related counters are good--including low SQL compiles/s
System	Processor Queue Length		2 x # of CPUs; threads waiting to be executed; >2 means CPU bottleneck
Access Methods	Full Scans/sec		(Index Searches/sec)/(Full Scans/sec) > 1000
Access Methods	Index Searches/sec		(Index Searches/sec)/(Full Scans/sec) > 1000
Access Methods	Mixed Page Allocations/sec		baseline
Access Methods	Page Splits/sec		baseline or <>
Access Methods	Mixed Page Allocations/sec		baseline
Access Methods	Workfiles Created/sec		baseline
Access Methods	Worktables Created/sec		baseline
Access Methods	Worktables from Cache Ratio		baseline
General Statistics	Temp Tables Creation Rate		baseline
General Statistics	Temp Tables for Destruction		baseline
Buffer Manager	Buffer Cache Hit Ratio		98% OK, 99% better, 99.8% desirable
Buffer Manager	Checkpoint pages/sec		baseline
Buffer Manager	Database Pages		<>
Buffer Manager	Lazy writes/sec		baseline
Buffer Manager	Page Life Expectancy		<300s>1,000 or >10,000s much better
Buffer Manager	Procedure Cache Pages		(2000) prefer stable values, otherwise cache thrash may be occurring
Plan Cache	Cache Pages		(2005) prefer stable values, otherwise cache thrash may be occurring
Buffer Manager	Total pages		baseline
Cache Manager	Cache Hit Ratio		<99.9>98 not optimal
Databases	Data File(s) Size (kb)
Databases	Log Flushes/sec		baseline
Databases	Percent Log Used
Databases	Transactions/sec		baseline
General Statistics	Logins/sec & Logouts/sec		baseline; >2/sec suggests app's implementation of connection pooling may be flawed
General Statistics	User Connections		~
Latches	Average Latch Wait Time (ms)		~
Latches	Latch Waits/sec		(Total Latch Wait Time) / (Latch Waits/Sec) <>
Latches	Total Latch Wait Time (ms)		(Total Latch Wait Time) / (Latch Waits/Sec) <>
Locks	Avg. Wait Time (ms)		~
Locks	Lock Timeouts/sec		> 0
Locks	Lock Wait Time (ms)
Locks	Lock Waits/sec		> 0
Locks	Number of Deadlocks/sec		> 0
Memory Manager	Granted Workspace Memory (KB)		baseline
Memory Manager	Memory Grants Pending		>0 is cause for concern
Memory Manager	Memory Grants Outstanding
Memory Manager	Target Server Memory		high or rising value indicates insufficient memory
Memory Manager	Total Server Memory		~=Physical Ram
SQL Statistics	Batch Requests/sec		OLTP workloads: server should support ~2,500/s/core
SQL Statistics	SQL Compilations/sec		if compiles > 10% of Batch Requests, then app may not be caching effectively
SQL Statistics	SQL Recompilations/sec		Recompiles > 10% of Compilations should be investigated
SQL Server:Buffer Manager	Free list stalls/sec		<>
SQL Server:Buffer Manager	Free pages		> 640
SQL Server:Buffer Manager	Lazy Writes/Sec		<>
SQLServer:Buffer Manager	Page lookups/sec		(Page lookups/sec) / (Batch Requests/sec) <>
SQL Server:Buffer Manager	Page reads/sec		<>
SQL Server:Buffer Manager	Page writes/sec		<>