- Author: [[znetlive.com]] - Full Title: How to Monitor Utilization of Disk I/O for Windows & Linux? - Tags:: [[Software Testing]] [[Load Testing]] [[Software Development]] [[Software Engineering]] [[Monitoring]] [[Server metrics]] - URL: https://www.znetlive.com/blog/monitor-disk-io-windows-linux/ - ### Highlights first synced by [[Readwise]] [[2020-09-17]] - When a user clicks to access any information, a request is shot to the web hosting server. Now, in the server, the data resides on files that are stored in Hard Disk Drives (HDDs) or more commonly, disks. To read the user requested data, the disk rotates to reach the required disk sector. This leads to waiting time, although of a few milliseconds, when the processor waits for that file to be read. (Similar thing happens during the write operation). This access time gradually adds up as the data-heavy servers process innumerable data requests and thus, retrieving the data from the storage device becomes a performance bottleneck. Thus, to prevent application performance hiccups from disk latency, it is important to monitor disk usage and disk I/O for possible performance issues, so that you can see which application is using the disk as an important part of its core functionality. - `Disk I/O includes read or write or input/output operations (defined in KB/s) involving a physical disk. In simple words, it is the speed with which the data transfer takes place between the hard disk drive and RAM, or basically it measures active disk I/O time. ` - Writes/sec – write operations rate. - Reads/sec – read operations rate. - Busy time – the % of the elapsed time when your particular disk drive was busy in servicing write or read requests. - Queue length – the number of requests on the disk that are in the queue. - Monitoring Linux Disk I/O activity using IOTOP and IOSTAT commands First of all, type top command in the terminal to check the load on your server. If the output is not satisfactory, then look into wa status to know the status of Reading and Write IOPS on the hard disk. If it is high, then we need to check I/O activity in Linux box using the iotop or iostat commands. By using iotop command, you can monitor the disk utilization by individual processes. - By typing the iotop command with o option, you will get the actual I/O activity. - With the help of iostat command, you will get the individual hard disk I/O activity. The below screenshot shows 28 and 17 percent of the utilization of disks. - With the help of the Windows Performance Monitor tool which is available in all versions of Windows, you can easily monitor the Windows disk usage. - Tap +sign and select the “Physical Disk” from the various “Performance Objects”. - Here, we select the below four counters. Don’t forget to click on Add after selecting each one. Avg. Disk sec/Transfer Disk Bytes/sec Disk Transfers/sec Avg. Disk Bytes/Transfer - Here, the Avg. Disk Bytes/Transfer provides the IO Size, Avg. Disk sec/Transfer is related to Average Latency, Disk Bytes/sec is equal to Throughput and last Disk Transfers/sec is IOPS. - IOPS is expressed in MB/sec, Windows 2003 displays values in Bytes/second. Convert them as 1Byte/sec = 1e-6 MB/sec.