How do I interpret iostat output?

To interpret the output of iostat, you need to know a little performance terminology:

1. Throughput is the rate at which a system completes operations, in units of operations per second.
2. Concurrency is the number of operations in progress at a time, either as an instantaneous measure or an average over an interval of time.

What is iostat describe its output and log files?

The iostat command in Linux is used for monitoring system input/output statistics for devices and partitions. It monitors system input/output by observing the time the devices are active in relation to their average transfer rates. iostat is being included in sysstat package.

How do I check iostat history in Linux?

How to Monitor Linux Systems Performance with iostat command

1. /proc/diskstats for disk stats.
2. /proc/stat for system stats.
3. /sys for block device stats.
4. /proc/devices for persistent device names.
5. /proc/self/mountstats for all the network filesystems.
6. /proc/uptime for information regarding system uptime.

What is await in iostat?

On linux iostat , the await column (average wait) is showing the average time spent by an I/O request computed from its very beginning toward its end. The svctm column (service time) should display the average time spent servicing the request, i.e. the time spent “outside” the OS.

What is %Util in iostat?

When iostat says %util, it means “Percentage of CPU time during which I/O requests were issued to the device”. The percentage of the time the drive was doing at least one thing. The iostat man page does provide a warning: Device saturation occurs when this value is close to 100% for devices serving requests serially.

What is use of Vmstat and explain its output and log files?

vmstat (virtual memory statistics) is a valuable monitoring utility, which also provides information about block IO and CPU activity in addition to memory. vmstat Basics. vmstat provides a number of values and will typically be called using two numerical parameters.

What is the use of iostat?

iostat (input/output statistics) is a computer system monitor tool used to collect and show operating system storage input and output statistics. It is often used to identify performance issues with storage devices, including local disks, or remote disks accessed over network file systems such as NFS.

How do I check iostat?

The command to display only a specific device is iostat -p DEVICE (Where DEVICE is the name of the drive–such as sda or sdb). You can combine that option with the -m option, as in iostat -m -p sdb, to display the statistics of a single drive in a more readable format (Figure C). Easy to read stats for a single device.

What does iostat mean in Linux?

monitoring system input/output device loading
The iostat command is used for monitoring system input/output device loading by observing the time the devices are active in relation to their average transfer rates. The iostat command generates reports that can be used to change system configuration to better balance the input/output load between physical disks.

How load is calculated in Linux?

On Linux, load averages are (or try to be) “system load averages”, for the system as a whole, measuring the number of threads that are working and waiting to work (CPU, disk, uninterruptible locks). Put differently, it measures the number of threads that aren’t completely idle.

How is the iostat command used in Linux?

The iostat command is used for monitoring system input/output device loading by observing the time the devices are active in relation to their average transfer rates. The iostat command generates reports that can be used to change system configuration to better balance the input/output load between physical disks.

What are the two main statistics in iostat?

From iostat there are two summary statistics which are Input/Output CPU wait time (iowait) and device utilization which are both expressed in terms of percentages. iowait is from the CPU’s perspective and it is the percentage of time that the CPU spent waiting for a IO device to be ready.

How to omit the current locale in iostat?

Tell iostat to omit output for any devices for which there was no activity during the sample period. If this variable exists and its value is ISO then the current locale will be ignored when printing the date in the report header. The iostat command will use the ISO 8601 format (YYYY-MM-DD) instead.

When does device saturation occur in iostat ( 1 )?

Note: In previous versions, this field was known as avgqu-sz. %util Percentage of elapsed time during which I/O requests were issued to the device (bandwidth utilization for the device). Device saturation occurs when this value is close to 100% for devices serving requests serially.