Fairly recently I came across this error message on one of my hosts “esx.problem.visorfs.ramdisk.full”
While trying to address the issue I had the following problems when the ramdisk did indeed “fill up”
- PSOD (worst case happened only once in my experience)
- VM’s struggling to vMotion from the affected host when putting into maintenance mode.
A reboot of the host would clear the problem (clear out the ramdisk) for a short while but the problem will return if not addressed properly.
- Clustered ESXi hosts (version 5.1)
- vCenter 5.1
First of all I had to see just how bad things were so I connected to the affected host via SSH ( you may need to start the SSH service on the host as by default it is usually stopped)
Using the following command I could determine what used state the ramdisk was in.
(using an example output)
It was clear the root was full so now to find out what was filling it up so I searched KB articles for answers below were more the more helpful ones.
Unlike many of the other articles I had read which all seemed to point to /var/log being the cause the culprit in this instance was the /scratch disk
After doing some quick reading it was clear I could set a separate persistent location for the /scratch disk. So I followed the VMware KB article on this process and rebooted the host to apply the changes.
Even though I had followed the article to the letter and rebooted the host the changes did not apply on this host as when I double checked the ramdisk and this was the output as you can see the used space was already growing and when I put the console window side by side with the other hosts it was growing rapidly whereas the other hosts were quite static in used space.
It was not until I rebooted the host again did the changes I made apply, I will point out that this was the only time this little issue occurred the other hosts only required one reboot after changing the /scratch location.
After the second reboot I could see the host was as it should be