Why does my virtual machine get so slow?

Question

What could cause a virtual machine to get really slow? I'm running vmware workstation with ubuntu 14.04 on a computer with quad core i7 processor, 8 GB of RAM and a decent hard drive (not ssd). I allocated 2 cores (4 logical processors) and 3GB RAM to the VM so it should have plenty of power. sometimes it's fine and other times it gets unusably slow for extended periods of time. i'm running a few browser tabs, text editor, postman, db server, http server and terminal tabs but i think this shouldn't be too much load for it given the hardware i allocated. i checked the task manager and sometimes it's just at 100% disk usage from the vm for minutes at a time. sometimes it gets stuck and just keeps reading without cooling down. does this happen to anyone else? it seems to only affect the vm. native OS remains relatively responsive during these high load periods.

Solution

I agree with Keltari. I think you are at the point where you have identified the issue, and perhaps it is disk related (as you mentioned the 100% usage) but you still need to do a bit more digging to find the culprit. This will be an exploration to find the issue so it is difficult to provide a step by step for where to go. I recommend reviewing all options for identifying the cause of the slowdown.

Take a look at some tools such as the ones presented here: http://www.tecmint.com/command-line-tools-to-monitor-linux-performance/

If it is disk based, tools such as lsof and iotop sound like a good place to start (assuming top and ps are not able to help you find the cause).