Bài giảng Cơ sở dữ liệu nâng cao Chapter 8 Monitoring SQL server

Bài giảng Cơ sở dữ liệu nâng cao Chapter 8 Monitoring SQL server Bài giảng Cơ sở dữ liệu nâng cao Chapter 8 Monitoring SQL server. Chương này trình bày một số nội dung The goal of monitoring, performance monitor, dynamic management views, monitoring events, event notifications,...

Monitoring SQL Server

The Goal of Monitoring

 The goal of monitoring databases is to see:

What’s going on inside SQL Server,

How effectively SQL Server is using the server resources (CPU, Memory, I/O)

 The information enables DBA identify

abnormal activities

The Goal of Monitoring

 Once you define your monitoring goals you should select the appropriate tools for

SQL Profiler: a graphical application that

enables you to capture a trace of events that occurred in SQL Server.

The Goal of Monitoring

 The following list describes the basic

monitoring tools:

SQL Trace: the T-SQL stored procedure way to invoke a SQL Server trace without having to

start up the SQL Profiler application It requires

a little more work to set up, but it’s a lightweight way to capture a trace

It’s scriptable  enables the automation of trace capture

Default trace: a light weight trace that runs in a continuous loop and captures a small set of key database and server events

useful in diagnosing events that may have occurred when no other monitoring was in place

The Goal of Monitoring

The following list describes the basic monitoring

Dynamic management views: return server state

information that can be used to monitor the health of a server instance, diagnose problems, and tune

performance

Transact-SQL: Some system stored procedures provide useful information for SQL Server monitoring, such as sp_who,sp_who2,sp_lock, and several others

Performance Monitor

 Performance Monitor is an important tool because it enables to know:

How SQL Server is performing

How Windows is performing.

 Three server resources needs to be

monitored:

CPU

Memory

I/O

Performance Monitor

 CPU Resource Counters:

Several counters show the state of the

available CPU resources.

Bottlenecks due to CPU resource shortages are frequently caused by problems such as:

More users than expected

One or more users running very expensive queries

Routine operational activities such as index rebuilding

Performance Monitor

 CPU Resource Counters:

The following counters will help to find the cause

of the bottleneck so that to identify that the

bottleneck is a CPU resource issue:

Processor: % Processor Time: displays the total percentage of time spent processing non-idle threads On a multiple-processor machine, each individual processor can be monitored

independently

Process: % Processor Time (sqlservr): can be used

to determine how much of the total processing time can be attributed to SQL Server

System: Processor Queue Length: displays the number of threads waiting to be processed by a CPU

Performance Monitor

 Disk Activity:

SQL Server relies on the Windows operating

system to perform I/O operations

The disk system handles the storage and

movement of data on your system Disk I/O is frequently the cause of bottlenecks in a system

Need to observe many factors in determining the performance of the disk system

Several disk counters return disk Read and

Write performance information, as well as data transfer information, for each physical disk or all disks

These are some Memory counters:

 Memory: Pages/Sec: measures the number of pages per second that re paged out of memory to disk or paged into memory from disk

 Memory: Available Bytes: indicates how much memory

is available to processes.

 Process: Working Set (sqlservr) - The SQL Server instance of the Working Set counter shows how much memory is in use by SQLServer.

Performance Monitor

 Memory Counters:

 SQL Server: Buffer Manager: Buffer Cache Hit Ratio - measures the percentage of time that data was found

in the buffer without having to be read from disk.

 This counter should be very high, optimally 90% or better When it is less than 90%, disk I/O will be too high, putting an added burden on the disk subsystem.

 SQL Server: Buffer Manager: Page Life Expectancy - returns the number of seconds a data page will stay in the buffer without being referenced by a data

Performance Monitor

 SQL Server Counters:

After installing SQL Server, a plethora of SQL Server performance objects and counters are configured to assist in the performance monitoring and

optimization of SQL Server

These are some SQL Server–specific counters:

 SQL Server: General Statistics: User Connections – displays the number of user connections that are currently connected to SQL Server

 This counter is useful in monitoring and tracking connection trends to ensure that the server is configured to adequately handle all connections

 SQL Server: Locks: Average Wait Time - monitor and track the average amount of time that user requests for data resources have to wait because of concurrent blocks

to the data.

Dynamic Management Views

 SQL Server 2008 provides many Dynamic

Management Views (DMVs) that can be used

in the gathering of baseline information and for diagnosing performance problems

 These views offer the same information as

Performance counters

Specific database performance information

Dynamic Management Views

sys.dm_os_performance_counters : this view provides the information such as Performance Monitor, except that the information is returned in a relational format and the values returned are instantaneous

sys.dm_db_index_physical_stats: returns information

about the indexes on a table, including:

 The amount of data on each data page

 The amount of fragmentation at the leaf and non-leaf level

of the indexes

 The average size of records in an index.

sys.dm_db_index_usage_stats: collects cumulative index usage data This view can be used to identify which

indexes are seldom referenced and, thus, may be

increasing overhead without improving Read

performance

Monitoring Events

 The following list describes the different

features you can use to monitor events that

happened in the Database Engine:

Monitoring Events

 SQL Server Profiler:

It’s a graphical tool that lets system

administrators monitor and record database and server activities.

Users can monitor the following events using SQL Server Profiler:

Login connections, attempts, failures, and disconnections

CPU use of a batch

Monitoring Events

 Working with SQL Server Profiler:

Defining a Trace:

Launch SQL Server Profiler

Connect to the SQL Server instance

Define how you want to see the trace data in the Trace Definition dialog box

Click the Events Selection tab to select the trace events and data columns to capture

After the trace is fully defined, click Run to launch the trace

Monitoring Events

 SQL Server Profiler:

Monitoring Events

 SQL Server Profiler:

Monitoring Events

 Working with SQL Server Profiler:

Starting, Pausing, and Stopping a Trace: After

a trace is running, you can control it from

within Profiler.

When you click Pause, the data gathering is suspended at the server level Any events that occur while the trace is paused are not captured

Stopping a trace closes the trace session

Monitoring Events

 Working with SQL Server Profiler:

Saving a Trace Log: There are a variety of ways

to save a trace definition or the data it

generates.

Saving a Trace Definition:

 After you create a new trace inside Profiler that contains the events, data columns, and filters that you want, click Run and then immediately stop the trace

 Under the File menu, go to the option Export, Script Trace Definition to generate a Transact- SQL batch to create a trace.

 Use this batch as the basis for a stored procedure that SQL Server Agent calls to manage the trace.

Event Notifications

 Event Notifications are database objects that send information about server and database events to a Service Broker

 Unlike creating traces, event notifications

can be used to perform an action inside an

instance of SQL Server in response to events.

Event Notifications

 The following steps are used to subscribe to

an event

Create the Service Broker queue that will

receive the details regarding the event In

addition, a queue requires the Service Broker service in order to receive the message.

Create an event notification You can create a stored procedure and activate it when the

event message is in the queue to take a certain action.

Troubleshooting SQL Server

 Management Studio: This tool enables you to perform most of your management tasks and

to run queries

 Some of the more common and advanced

features can be used for administration:

You must have access to each database you wish

to report on, or your login must have enough

rights to run the server-level report.

selecting Reports from the menu

A report favorite at the server level is the Server Dashboard

Troubleshooting SQL Server

 Reports:

Server Reports:

Troubleshooting SQL Server

 Reports:

Server Reports:

The Server Dashboard report gives user a wealth

of information about your SQL Server 2008 instance:

 What edition and version of SQL Server

 Anything for that instance that is not configured

to the default SQL Server settings

 The I/O and CPU statistics by type of activity (e.g., ad hoc queries, Reporting Services, and soon)

 High-level configuration information such as whether the instance is clustered or using AWE

against a database, users being blocked, or disk utilization for a given database

Troubleshooting SQL Server

 Reports:

Database Reports:

Troubleshooting SQL Server

 Configuring SQL Server:

2 ways for SQL Server configuration:

SQL Configuration Manager

The sp_configure stored procedure

2 ways for the Database Engine configuration:

The sp_configure stored procedure

The Server Properties screen

To filter the objects in Management Studio:

Select the node of the tree that you wish to filter and click the Filter icon in the Object Explorer

In the Object Explorer Filter Settings dialog, filter

by name, schema, or when the object was created The Operator drop-down box enables to select

how wish to filter, and then type the name in the Value column

Troubleshooting SQL Server

 Filtering objects

Troubleshooting SQL Server

 Error log:

When something goes wrong with an application, the first thing should be done is connecting to the server and looking at the SQL Server instance

error logs and the Windows event logs.

To view the logs, right-click SQL Server Logs

under the Management tree and select View  SQL Server and Windows Log to open “Log File Viewer” screen

From this screen, user can check and uncheck

log files that you want to bring into the view or

can consolidate logs from SQL Server, Agent,

Database Mail, and the Windows Event Files.

Troubleshooting SQL Server

 Error log:

 Data File I/O

 Recent Expensive Queries

Troubleshooting SQL Server

 Activity monitoring:

 To see all the connections to your server, run sp_who2

without any parameters.

 To see only the active connections to your server, execute this command:

sp_who2 ‘active’

sys.dm_exec_connections: gives more information

to help to troubleshoot the Database Engine.

Troubleshooting SQL Server

 Process monitoring:

DBCC INPUTBUFFER: is a great DBCC

command that enables to see what SQL

command an individual process ID is running

The command accepts only a single input parameter, which is the process id for the connection that you’d like to diagnose

Ex: DBCC INPUTBUFFER (55)

Performance Tuning

 The goal of monitoring databases is to

assess how a server is performing

 Effective monitoring current performance

is go isolate processes that are causing

problems, and gathering data continuously over time to track performance trends

 Evaluate user activity.

 Troubleshoot any problems or debug application components, such as stored procedures.

Performance Tuning

 Monitoring lets administrators

identify performance trends to

determine if changes are necessary

Performance Tuning

 To monitor SQL Server effectively 

should clearly identify your reason for monitoring

 Establish a baseline for performance.

 Identify performance changes over time.

 Diagnose specific performance problems.

 Identify components or processes to

Performance Tuning

 To monitor SQL Server effectively  should clearly identify your reason

for monitoring

 Test a server under different loads

Test database architecture.

 Test maintenance schedules.

 Test backup and restore plans.

 Determining when to modify your

hardware configuration.

Performance Tuning

 The performance of enterprise

database systems depends on:

 A effective configuration of physical design strunctures in the databases that compose those systems

 These physical design structures

include indexes, clustered indexes, indexed views, and partitions, whose purpose is to enhance performance and manageability of databases

Performance Tuning

 SQL Server provides Database

Engine Tuning Advisor - a tool that analyzes the performance effects of workloads (a set of Transact-SQL

statements that executes against

databases you want to tune) on one

or more databases.