What is I/O usage?
I/O (input/output is measured in KB/s) is just the “throughput” or speed of data transfer between the hard disk and the RAM. On a server, a disk I/O describes every process that involves writing to or reading from a storage device which on a shared web hosting server will be the hard disk drive or HDD. I/O processes to an HDD are particularly slow when compared with solid-state memory such as RAM, HDD I/O is, on average, 2,000 times slower.
Why is I/O usage is increased?
Mainly the I/O is caused due to the increase in Data output and input or you can say increased in reading speed and writing speed in the disc. If you are the owner of a VPS or Dedicated server and while creating a ZIP file from the files of 20 and each file is having 10 GB then it will take a lot of time and hence increase in I/O usage.
Another reason is due to high-resolution images. If you are having high-resolution images, either reduce their size or upload those photos to flicker or any website like that which will give a hotlink to that image. Then use it on your website. So i/o usage from your server will be reduced.
Disk I/O may be referred to as simply IO, but in either case, is short for input/output. This limit refers to the maximum number of interactions your server can have (whether inbound or outbound) with the outside world at the same time. This might be such things as serving website pages to visitors, or uploading/downloading files etc.
Input/Output Per Second
Sometimes referred to as IOPS, this is the total number of individual read/write operations per second that your server can do. This is directly related to Disk I/O and servers with SSD storage drives are much more capable of a high IOPS limit than HDDs (spin-up) storage drives.
