Iotop monitor linux disk io activity and usage perprocess basis. One way to track disk usage on a linux system is by using the vmstat tool. Swap space if you find more than 30%40% utilization, disk io may slowing you. This is our ongoing series of commands and performance monitoring in linux. Its more difficult to detect an io bottleneck if the disk isnt on your desktop. Ive been facing disk io bottleneck on one of my streaming server, but couldnt identify the limiting factor. How do i determine my linux boxs performance bottleneck. Disk performance is one of the complex issues and this blog neither attempts nor can solve all issues. Tips to check and improve your storage io performance with. There some tools like iostat, sar, vmstat very useful to troubleshoot the performance issues and these tools are commonly available in all unix linux operating systems.
To calculate the available memory add the value in free and cache columns. Disk io includes read or write or inputoutput operations defined in kbs. But what if your program is slower than it should be because it waits for io disk operations. One of the common causes of this condition is disk io bottleneck. I wrote a comprehensive guide to tracking down performance bottlenecks on linux. Disk io is input output writeread operations on a physical disk or other.
Therefore it is possible to see linux systems with gigabytes of memory but only have few megabytes of memory free. Here we are going to see the logical approach of problem solving. Lets take a look at some useful techniques, and some of the easier solutions to each area if you find problems. You can check your io wait percentage via top, a command available on every flavor of linux. First of all, the command to show io statistics on linux is iostat. In the example above, disk access took 700 ms, so io wait is 70%. There are a number of benchmarking applications software that can be used as hard disk storage stress testing. The stress test of hardware hard drive benchmarks is a simplistic test. Performance monitoring iostat identify io bottlenecks. Disk io is inputoutput writeread operations on a physical disk or other. Performance monitoring iostat identify io bottlenecks by ramdev march 22, 2011 generally a problem is identified when an application is not performing as expected. Identify performance bottlenecks in linux system techsquids.
Discussing about using various builtin performance monitoring tools like iostat, prstat, vmstat etc. Linux handle free memory differently to that of other os. Vmstat and iostat both commands are available on all major unixlike operating systems. If there is less amount of memory available in the system, it may start swapping and the performance will get impacted. To begin, lets looks at how we can confirm if disk io is slowing down application performance by using a few terminal command line tools top, atop and iotop on a lemp installed dedicated server. Handy for answering the question why is my disk churning so much. The app administrator wants to know how much iops a certain lun can provide. The default configuration is to allocate all available free memory space as disk space.
Linux offers a huge collection of tools for collecting and viewing information about each. How to monitor its utilization for windows and linux. When we know the problem exists, then we should proceed for the identification of bottleneck by collecting data when a disk issue found it will need to be investigated and the following data collected. Disk io encompasses the inputoutput operations on a physical disk. The available memory in linux systems is used for caching and is governed by internal memory management system. Io wait, more about that below is the percentage of time the cpu has to wait on disk. Troubleshooting io performance issues on linux youtube. Monitor disk io utilization on servers with linux and windows os. Linux performance monitoring with vmstat and iostat commands.