Please refer the script for monitoring the disk activity.
This script will display Disktranferpersec, Disk KBytes/sec(Throughput), Disk Reads/sec, Disk Writes/sec, PercentDisktime, DISK IDLE TIME, Avg.Disk Bytes/Transfer(Io Size), Avg.DiskSec/transfer(Average Latency)seconds.
Please run the script as the System Administrator.
here in the script, threshold=10, you can replace threshold value based upon your requirement.
Please refer the wiki guide for how to use the custom monitoring scripts: