Iostat is one of the most useful command when troubleshooting a disk I/O performance issue. It can also be used to troubleshoot a CPU performance issue as well. The iostat command can be run in various ways.

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Summary since boot

By default if you run iostat without any options it will show the summary since boot which is very useful to compare the system performance in a bottleneck vs average system performance.
Example 1

The output shows all the device instances as well as terminal and cpu statistics. Below are the parameter being displayed :

Current statistics

The current disk I/O statistics need to be analyzed, which can be done by running iostat over some period of time. The syntax to run iostat at some interval with some optional count is :

Example 2
To run iostat at 1 seconds interval with a count of 5 :

Display Only disk statistics

Classic style
The default iostat also shows the CPU statistics. To display only the disk statistics use the -d otion. This would print disk statistics in a classic way with kps, tps and serv values.

Example 3

I actually have 5 disks in my system, but the above output only shows disk statistics for 4 disk only. That’s because the default iostat command shows disk statistics only for first 4 disks. To print disk statistics for more than 4 disk we can use -l option ( we can provide number of disks for which we want disk statistics with l )

Example 4

In the example above 5 is number of disk to print the statistics for and (1 3) is the interval and count respectively.

New style
In the latest style of iostat command with option -D, we get rps (reads per second), wps (write per second), and util (% utilization).

Example 5

Statistics for a specific disk(s)

We can also get disk I/O statistics only for a specific disk or set of disk using iostat :

Example 6

Remember to limit the disks shown in output with l, otherwise it would print all disk anyways.

To print logical disk names

Most of the times we understand logical disk names. So to print disk I/O statistics using the logical disk names use the option -n :

Example 7

Extended Device statistics

The option -x displays the extended device statistics.

Example 8

The extended statistics shows some extra info such as reads/sec (r/s), writes/sec (w/s), kilobytes read and kilobytes write per sec (kr/s and kw/s), avg. active transactions (actv), average service time (svc_t) etc.

Per partition statistics

with the -p option we can also print the per partition io statistics if we want.

Example 9

Error Statistics

To check for hard and soft errors on disk use the -e option with iostat command :
Example 10

The various errors are :

The various errors statistics can also be displayed with -E option :

Example 11

Combining multiple options

Now when using iostat, we usually combine 3 or 4 options to give you only the output in which we are interested. As show in below example we would only get non-zero lines, with logical disk name, extended statistics etc by combining various options in iostat example.

Example 12

Use powercfg.exe to control power plans - also called power schemes - to use the available sleep states, to control the power states of individual devices, and to analyze the system for common energy-efficiency and battery-life problems.

Syntax

Powercfg command lines use the following syntax:

powercfg /option [arguments] [/?]

where option is one of the options listed in the following table, and arguments is one or more arguments that apply to the selected option. Including /? in a command line displays help for the specified option. Options and arguments are described in more detail later in this topic.

Command-line options

Command-line option descriptions

The following sections describe Powercfg command-line options and arguments.

-help or /?

Displays information about command-line parameters.

Syntax:

powercfg /?

/list or /L

Lists all power schemes.

Syntax:

powercfg /list

/query or /Q

Displays the contents of the specified power scheme.

Syntax:

powercfg /query [scheme_GUID] [sub_GUID]

If neither the parameter scheme_GUID or sub_GUID are provided, the settings of the current active power scheme are displayed. If the parameter sub_GUID is not specified, all settings in the specified power scheme are displayed.

Arguments:

scheme_GUID

Specifies a power scheme GUID. Running powercfg /list returns a power scheme GUID.

sub_GUID

Specifies a power-setting subgroup GUID. A power setting subgroup GUID is returned by running powercfg /query.

Examples:

/change or /X

Modifies a setting value in the current power scheme.

Syntax:

 /change settingvalue

Arguments:

setting

Specifies one of the following options:

• monitor-timeout-ac
• monitor-timeout-dc
• disk-timeout-ac
• disk-timeout-dc
• standby-timeout-ac
• standby-timeout-dc
• hibernate-timeout-ac
• hibernate-timeout-dc

value

Specifies the new value, in minutes.

Examples:

/changename

Modifies the name of a power scheme and optionally its description.

Syntax:

 powercfg /changename *scheme_GUID * name [description]

Arguments:

scheme_GUID

Specifies a power scheme GUID. Running powercfg /list returns a power scheme GUID.

name

Specifies the power scheme's new name.

description

Specifies the power scheme's new description. If no description is specified, only the name is changed.

Examples:

/duplicatescheme

Duplicates the specified power scheme. The resulting GUID which represents the new scheme is displayed.

Syntax:

 powercfg /duplicatescheme scheme_GUID [destination_GUID]

Arguments:

scheme_GUID

Specifies a power scheme GUID. A power scheme GUID is returned by running powercfg /list.

destination_GUID

Specifies the new power scheme's GUID. If no GUID is specified, a new GUID is created.

Examples:

/delete or /D

Deletes the power scheme with the specified GUID.

Syntax:

 powercfg /delete scheme_GUID

Arguments:

scheme_GUID

Specifies a power scheme GUID. A power scheme GUID is returned by running powercfg /list.

Examples:

/deletesetting

Deletes a power setting.

Syntax:

 powercfg /deletesetting sub_GUIDsetting_GUID

Arguments:

sub_GUID

Specifies a power setting subgroup GUID. A power setting subgroup GUID is returned by running powercfg /query.

setting_GUID

Specifies a power setting GUID. A power setting GUID is returned by running powercfg /query.

Examples:

/setactive or /S

Makes the specified power scheme active on the system.

Syntax:

 powercfg /setactive scheme_GUID

Arguments:

scheme_GUID

Specifies a power scheme GUID. A power scheme GUID is returned by running powercfg /list.

Examples:

/getactivescheme

Retrieves the currently active power scheme.

Syntax:

 powercfg /getactivescheme

/setacvalueindex

Sets the value associated with a specified power setting while the system is powered by AC power.

Syntax:

 powercfg /setacvalueindex scheme_GUIDsub_GUIDsetting_GUIDsetting_index

Arguments:

scheme_GUID

Specifies a power scheme GUID. A power scheme GUID is returned by running powercfg /list.

sub_GUID

Specifies a power setting subgroup GUID. Running powercfg /query returns a power setting subgroup GUID.

setting_GUID

Specifies a power setting GUID. A power setting GUID is returned by running powercfg /query.

setting_index

Specifies which possible value this setting is set to. A list of possible values is returned by running powercfg /query.

Examples:

/setdcvalueindex

Sets the value associated with a specified power setting while the system is powered by DC power.

Syntax:

 powercfg /setdcvalueindex scheme_GUIDsub_GUIDsetting_GUIDsetting_index

Arguments:

scheme_GUID

Specifies a power scheme GUID. A power scheme GUID is returned by running powercfg /list.

sub_GUID

Specifies a power setting subgroup GUID. A power setting subgroup GUID is returned by running powercfg /query.

setting_GUID

Specifies a power setting GUID. A power setting GUID is returned by running powercfg /query.

setting_index

Specifies which possible value this setting is set to. A list of possible values is returned by running powercfg /query.

Examples:

/import

Imports a power scheme from the specified file.

Syntax:

 powercfg /import file_name [GUID]

Arguments:

file_name

Specifies a fully-qualified path to a file returned by running powercfg /export.

GUID

Specifies the GUID for the imported scheme. If no GUID is specified, a new GUID is created.

Examples:

/export

Exports a power scheme, represented by the specified GUID, to the specified file.

Syntax:

 powercfg /export file_nameGUID

Arguments:

file_name

Specifies a fully-qualified path to a destination file.

GUID

Specifies a power scheme GUID. A power scheme GUID is returned by running powercfg /list.

Examples:

/aliases

Displays a list of aliases and their corresponding GUIDs. These aliases may be used instead of a GUID in any command.

Syntax:

 powercfg /aliases

Note

Some settings do not contain aliases. For a full list of GUIDs, use powercfg /query.

/getsecuritydescriptor

Gets the security descriptor associated with the specified power setting, power scheme, or action.

Syntax:

 powercfg /getsecuritydescriptor GUIDaction

Arguments:

GUID

Specifies a power scheme or a power setting GUID. A power scheme GUID is returned by running powercfg /list. A power setting GUID is returned by running powercfg /query.

action

Specifies one of the following actions:

• ActionSetActive
• ActionCreate
• ActionDefault

Examples:

/setsecuritydescriptor

Sets a security descriptor associated with the specified power setting, power scheme, or action.

Syntax:

 powercfg /setsecuritydescriptor GUIDactionSDDL

Arguments:

GUID

Specifies a power scheme or a power setting GUID. A power scheme GUID is returned by running powercfg /list. A power setting GUID is returned by running powercfg /query.

action

Specifies one of the following actions:

• ActionSetActive
• ActionCreate
• ActionDefault

SDDL

Specifies a valid security descriptor string in SDDL format. An example SDDL string can be obtained by running powercfg /getsecuritydescriptor.

Examples:

/hibernate or /H

Enables or disables the hibernate feature; also, sets the hiberfile size.

Syntax:

 powercfg /hibernate

 powercfg /hibernate [ onoff ]

 powercfg /hibernate [ /size percent_size]

 powercfg /hibernate [ /type reducedfull ]

Arguments:

On

Enables the hibernate feature.

 Off

Disables the hibernate feature.

 /size percent_size

Specifies the desired hiberfile size as a percentage of the total memory size. The default size cannot be smaller than 50. This parameter also causes hibernation to be enabled.

 /type reducedfull

Specifies the desired hiberfile type. A reduced hiberfile only supports hiberboot.

Note

A hiberfile that has a custom default size, or HiberFileSizePercent >= 40, is considered as a full hiberfile. HiberFileSizePercent is set in the registry in HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlPower.

To change the hiberfile type to reduced, the OS has to manage the default hiberfile size. To do this, run the following commands:

powercfg /hibernate /size 0

powercfg /hibernate /type reduced

Examples:

/availablesleepstates or /A

Reports the sleep states available on the system. Attempts to report reasons why sleep states are unavailable.

Syntax:

 powercfg /availablesleepstates

/devicequery

Returns a list of devices that meet the specified criteria.

Syntax:

 powercfg /devicequery query_flag

Arguments:

query_flag

Specifies one of the following criteria:

wake_from_S1_supported Returns all devices that support waking the system from a light sleep state.

wake_from_S2_supported Returns all devices that support waking the system from a deeper sleep state.

wake_from_S3_supported Returns all devices that support waking the system from the deepest sleep state.

wake_from_any Returns all devices that support waking the system from any sleep state.

S1_supported Lists devices supporting light sleep.

S2_supported Lists devices supporting deeper sleep.

S3_supported Lists devices supporting deepest sleep.

S4_supported List devices supporting hibernation.

wake_programmable Lists devices that are user-configurable to wake the system from a sleep state.

wake_armed Lists devices that are currently configured to wake the system from any sleep state.

all_devices Returns all devices present in the system.

Examples:

/deviceenableawake

Enables the specified device to wake the system from a sleep state.

Syntax:

 powercfg /deviceenableawake device_name

Arguments:

device_name

Specifies a device. This device name may be retrieved using powercfg /devicequery wake_programmable.

Examples:

/devicedisablewake

Disables the specified device from waking the system from a sleep state.

Syntax:

 powercfg /devicedisablewake device_name

Arguments:

device_name

Specifies a device. This device name may be retrieved using powercfg /devicequery wake_armed.

Examples:

/lastwake

Reports information about what woke the system from the last sleep transition.

Syntax:

 powercfg /lastwake

/waketimers

Enumerates the active wake timers. If enabled, the expiration of a wake timer wakes the system from sleep and hibernate states.

Syntax:

 powercfg /waketimers

/requests

Enumerates application and driver Power Requests. Power Requests prevent the computer from automatically powering off the display or entering a low-power sleep mode.

Syntax:

 powercfg /requests

/requestsoverride

Sets a Power Request override for a particular process, service, or driver. If no parameters are specified, this command displays the current list of Power Request overrides.

Syntax:

 powercfg /requestsoverride [caller_typenamerequest]

Arguments:

Caller_type

Specifies one of the following caller types: process, service, driver. This is obtained by running powercfg /requests.

name

Specifies the caller name. This is the name returned by running powercfg /requests.

request

Specifies one or more of the following Power Request types:

• Display
• System
• Awaymode

Examples:

/energy

Analyzes the system for common energy-efficiency and battery-life problems and generates a report, an HTML file, in the current path.

Syntax:

 powercfg /energy [ /output file_name] [ /xml ] [ /duration seconds ]

 powercfg /energy /trace [ /d file_path] [ /xml ] [ /duration seconds]

 The /energy option should be used when the computer is idle and has no open programs or documents.

Arguments:

 /output file_name

Specify the path and file name to store the energy report HTML or XML file.

 /xml

Formats the report file as XML.

 /duration seconds

Specifies the number of seconds to observe system behavior. Default is 60 seconds.

 /trace

Records system behavior and does not perform analysis. Trace files are generated in the current path unless the /D parameter is specified.

 /d file_path

Specify the directory to store trace data. May only be used with the /trace parameter.

Examples:

/batteryreport

Generates a report of battery usage characteristics over the lifetime of the system. Running powercfg /batteryreport generates an HTML report file in the current path.

Syntax:

 powercfg /batteryreport [ /output file_name ] [ /xml ]

 powercfg /batteryreport [ /duration days ]

Arguments:

 /output file_name

Specify the path and file name to store the battery report HTML.

 /output file_name /xml

Formats the battery report file as XML.

 /duration days

Specifies the number of days to analyze for the report.

Examples:

/sleepstudy

Generates a diagnostic report of modern standby quality over the last three days on the system. The report is a file that is saved in the current path.

Syntax:

 powercfg /sleepstudy [ /output file_name ] [ /xml ]

 powercfg /sleepstudy [ /duration days]

 powercfg /sleepstudy [ /transformxmL file_name.xml ] [ /output file_name.html ]

Arguments:

 /output file_name

Specify the path and file name to store the Sleepstudy report HTML.

 /output file_name /xml

Formats the Sleepstudy report file as XML.

 /duration days

Specifies the number of days to analyze for the report.

 /transformxml file_name.xml /output file_name.html

Transforms the Sleepstudy report from XML to HTML.

Examples:

/srumutil

Enumerates the entire Energy Estimation data from the System Resource Usage Monitor (SRUM) in an XML or CSV file.

Syntax:

 powercfg /srumutil [ /output file_name ] [ /xml ] [ /csv ]

Arguments:

 /output file_name

Specify the path and file name to store the SRUM data.

 /output file_name /xml

Formats the file as XML.

 /output file_name /csv

Formats the file as CSV.

Examples:

/systemsleepdiagnostics

Generates a report of intervals when the user was not present over the last three days on the system, and if the system went to sleep. This option generates a report, an HTML file, in the current path.

This command requires administrator privileges and must be executed from an elevated command prompt.

Syntax:

 powercfg /systemsleepdiagnostics [ /output file_name ] [ /xml ]

Arguments:

 /output file_name

Specifies the path and file name of the diagnostics report.

 /xml

Save the report as an XML file.

 /duration days

Specifies the number of days to analyze for the report.

 /transformxml file_name

Produces a report in HTML from a report that was previously created in XML.

Examples:

/systempowerreport or /spr

Generates a report of system power transitions over the last three days on the system, including connected standby power efficiency. This option generates a report, an HTML file, in the current path.

This command requires administrator privileges and must be executed from an elevated command prompt.

Syntax:

 powercfg /getsecuritydescriptor GUIDaction

Arguments:

 /output file_name

Specifies the path and file name of the diagnostics report.

 /xml

Save the report as an XML file.

 /duration days

Specifies the number of days to analyze for the report.

 /transformxml file_name

Produces a report in HTML from a report that was previously created in XML.

Examples: