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You can also run iotop with multiple iterations.

The following command accomplishes iotop -btoqq -iter=1ġ7:53:54 Total DISK READ : 0.00 B/s | Total DISK WRITE : 0.00 B/sġ7:53:54 Actual DISK READ: 0.00 B/s | Actual DISK WRITE: 0.00 B/s For instance, maybe you only want global disk usage data. If the current iotop display is too coarse, there are ways to run it that display more precise details. While it would still be writing to disk, letting a process persist storage using its own mechanisms is likely faster than having it page memory in and out of swap. This may be an indication that the process’s memory use should be reduced somehow. The SwapIn column lets you determine how much a given process is hitting swap. If a program is behaving badly, there may be configuration tweaks that can be made to reduce its disk use, perhaps making it rely more on RAM.

You can use the IO percentage value to determine a program’s disk access as it relates to total drive bandwidth.

If an application is performing many disk reads or writes, you’ll notice it at the top of the list. If you’ve followed this guide’s recommendation, you’ve installed it on a server that is mostly idle. Now we run the newly-installed iotop command, at which point we’ll get regularly updated statistics on disk use.Īt the moment the iotop results aren’t terribly interesting. The iotop package is included in the official CentOS 7 package repositories, so we only need to install it. While it will work on a production server, it is recommended that you familiarize yourself with iotop on an instance that isn’t critical to your operations before using this knowledge on a live system.

In this guide, we’ll install iotop on CentOS 7, and will introduce its use so you’ll know how to instrument production servers. Regardless of the cause, iotop is a critical tool in determining if excessive disk access is degrading server resources. Maybe a program is performing lots of writes, or numerous swap hits are causing performance to degrade. Hard drive performance is often a bottleneck when diagnosing why a server may be running more slowly.