- Tags:: [[Software Testing]] [[Load Testing]] [[Software Development]] [[Software Engineering]] [[Monitoring]] [[Server metrics]] - Date Created: [[2020-09-14]] - Last Updated: [[2020-09-29]] - Source: - [[Performance Testing Basics What Is Resource Utilization]] [[Joe Colantonio]] - [[How to Monitor Utilization of Disk IO for Windows and Linux]] - This is often confused with memory, particularly Read-Only Memory (ROM), but the disk actually refers to the hard drive storage of a server. For load testing, the important aspect of disk is not the storage __space__ that is available but how it is managed. - This group of metrics is sometimes called "Disk I/O" for Disk input and output, because they measure how quickly information is read from the disk. - "`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. `" - Here are the most important Disk metrics: - Average Disk Queue Length - Average Disk Read Queue Length - Average Disk Write Queue Length - Average Disk sec/Read - Average Disk sec/Transfer - Disk Reads/sec - Disk Writes/sec - "Busy time – the % of the elapsed time when your particular disk drive was busy in servicing write or read requests." - Disk bottlenecks can occur in an application when there are too many read and write operations for a disk. - "`How to Find a Disk bottleneck formula: I/Os per Disk = [Read + (4xWrites)] / Number of Disk (To see a step-by-step example of how to use this formula, take a look at pg. 84 & 85 of the Microsoft book I mentioned earlier) `" - [[Getting Disk Metrics on Linux]] - [[Getting Disk Metrics on Windows]]