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. It can also be used to provide information about terminal (TTY) input and output, and also includes some basic CPU information. Syntax and availability iostat -x displays output where each line (row) gives numerical data for one device. The first column lists the device name, and subsequent columns show various statistics for that device. Columns include the average service time (svc_t, which includes not only the time a request is in the service queue, but also the seek time and transfer time), the average busy percentage (%b, essentially the proportion of time that the device is in use), and the percentage of time that the queue is not empty (%w, which means the proportion of time in which requests from the device have not yet been fulfilled). It is best to run iostat specifying a time interval in seconds (for example iostat -x 30) in order to see the results over time. This is