Impact of RAMDisk when ESXi host goes down

[WillemDH]

Hello,

What would be the impact on Nagios XI if we would use a RAMDisk following http://assets.nagios.com/downloads/nagi ... giosXI.pdf and the ESXi host goes down (no power)?

Grtz

Willem

[ssax]

You will lose all the data in the RAMDisk when you power it off/on but it will be rebuilt.

Edit: If you were trying to store things that don't get rebuilt like say your nagios.cfg file then that would not be recoverable.

[WillemDH]

So no perfdata or any Nagios config would be lost?

[ssax]

At most it will lose 15 seconds of perfdata depending on how you have it configured.

[ssax]

No Nagios config would be lost if you followed the guide.

You could technically store anything you wanted on there but because it is volatile it will be lost on a reboot, that's why the guide shows the files that will get rebuilt.

[WillemDH]

Thanks, I will try the procedure begining next week. Please leave this thread open for a week or so.

[jdalrymple]

Be aware that in a VMware environment you may have to do some tuning to guarantee that your RAMDISK is indeed on physical memory. In a memory constrained host your guest's memory could end up being placed in the vswp file, which to your guest still appears to be physical memory but in reality it's physical disk. VMware does a very good job of placing most frequently used data where it should be and least recently used data where it should be, however on a deeply overcommitted host there is only so much it can do.

For tuning information review this dated but still very applicable white paper:

http://www.vmware.com/files/pdf/perf-vs ... gement.pdf