RFi: FileSystem Performance

Description

This visualization shows the speed of your computer’s filesystem (aka disk).

Your computer needs somewhere to keep information permanently. This is called disk or filesystem. It is different to the memory where it keeps things temporarily.

This filesystem/disk space is used to save your files like spreadsheets and documents but it is also used to store programs and other system information. It is also used to temporarily store the contents of memory when your computer needs to free up some memory space for a while.

Memory is super fast but disk is relatively slow so the process of reading and writing to disk can really slow down your computer if your disks are performing too slowly.

Real-world impacts

If you are suffering from poor performance on your computer it could be because of external things like the network being slow or busy or it could be because of things on your computer being busy – slow disks can be a cause of this.

Slow disk/filesystem performance could result in slow application startup times or slow load times for spreadsheets and documents. It can also slow down the process of memory paging which has an overall slowing effect on your machine.

Poor disk/filesystem performance is a “slow down” issue – your computer is working but just taking too long to do certain things.

What to look for

In this visualization a lower number means slower disk/filesystem performance.

Look for dips in disk/filesystem performance that coincide with you experiencing slow performance on your computer.

It is hard to put a number on good and bad throughput but to give an example a 2012 MacBook laptop with a 480Gb SSD disk is getting an average of 10MBytes/s of write throughput and about 500MBytes/s of read throughput. The peaks are much higher.

Different disk types (hard disks vs SSD disks), interfaces and other techie stuff can cause huge differences in the expected throughput so rather than looking for good and bad numbers, focus on comparing the performance of your disks when your computer is slow and fast to see if disk/filesystem performance is a factor.

Bear in mind that this visualization is measured on a logarithmic scale, not a linear one – look carefully at the scale/numbers on the left vertical axis and you will see what we mean.

How do we test

We periodically write and then read (and then remove) a temporary test file to your disk/filesystem.

We measure how long it takes to write the file and then how long it takes to read the file. This gives us a write and read throughput measured in megabytes per second or gigabytes per second.

As mentioned above, be sure to read the scale carefully in the visualization as it is logarithmic and the values can change from MBytes/s to GBytes/s as you go up the scale.

What could cause poor filesystem/disk performance

A disk with errors can cause retries when writing so it is worth checking this out.

A badly fragmented disk can also slow things down as it needs to do more work to find space for a file or to gather all of the scattered bits of a file. Defragmenting your disk may help.

It is possible that old age (well old technology) can cause slow disk performance but don’t rush to this conclusion.

Finally, a process constantly writing to, or reading from the disk can cause a slowdown for other applications. take a look at the real-time overall read and write rates for your filesystem/disks when you experience slowdowns in case this is happening.

Next steps to diagnose or repair for Residential Trial Customers

Firstly have a think about whether you feel your computer is running slow – just because the visualization shows your disk performance has highs and lows does not mean your computer is slow.

If you feel the computer is sometimes ‘slow’ and the visualization shows your disk performance is not dipping at the times slowness is experienced then look elsewhere – CPU or memory performance are worth a look. If it is slow when doing things that use the network, look at the network-based visualizations (Throughput, Loss, Latency, DNS etc) for performance issues.

If the slowness is not related to network activities take a look at the other computer platform related visualizations such as CPU and Memory performance.

If your computer is slow and the filesystem/disk visualization looks like filesystem/disk dips when you experience slowness then you will need to troubleshoot what is causing these dips.

Start by looking for disk errors and fix those – google is your friend here but be sure to do lots of backups before you go too far!

Then assess whether your disk is heavily fragmented – most platforms have a built-in defragmentation regime and worst case you can take a backup and then restore it to get things sorted out.

Also look at your Task manager, Activity monitor or ‘top’ utility to see if there is a process or application doing lots of filesystem/disk activity at the time you experience slowdowns.

You can also look to see if the disk is nearly full (or has been nearly full when you experience slowness) as this can cause issues with finding space for writing files and can impact the overall filesystem/disk performance. Take a look at the disk space visualization for this information

Finally, see if you can compare the performance of your disk with a similar machine using similar disk technology and running the same kind of operating system. If they are performing about the same and the other machine is not experiencing the same performance issues then you might be able to assume the filesystem/disk is not the culprit and start looking elsewhere.