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How to tell if a RamDisk is being used as expected
Posted: Thu Jan 09, 2020 4:00 pm
by Matthew.Cary
My Org is running XI on a single node with 1000 Hosts & 9500 Services and want to make sure we are following all the performance optimization best practices.
We have setup a RAMDisk per the XI Documentation and set it to 500M, but when we look out at the RamDisk from the OS it only shows it using 25M of space.
Is this expected? How much space should we expect files to take up on this disk?
Re: How to tell if a RamDisk is being used as expected
Posted: Thu Jan 09, 2020 5:59 pm
by Box293
Normally a ramdisk shouldn't use that much space as the intended use is for temporary files to be written / deleted very quickly.
Exactly how much space being used totally depends on many factors.
If you look at the documentation
https://assets.nagios.com/downloads/nag ... giosXI.pdf it lists the directories / files that should exist in specific locations. Check these files to asses their sizes and make a judgement from there.
Once you have a baseline on "normal usage" then you could implement a disk space check to ensure the ramdisk doesn't exceed this usage. If it does then something is wrong and hopefully you'll catch it before it becomes an issue.
Does this help?
Re: How to tell if a RamDisk is being used as expected
Posted: Fri Jan 10, 2020 12:33 pm
by Matthew.Cary
I'm not sure.
So if I understand you the file usage is transient & it may be normal for us to only be using 5% of our Ramdisk?
I'll take your advice and set a disk monitor to try to get some history on this. That may help me understand this better.
Does it make sense to move MRTG files to the Ramdisk? or is that a bad idea?
Re: How to tell if a RamDisk is being used as expected
Posted: Fri Jan 10, 2020 1:25 pm
by tacolover101
yes, it is all pending how much files are in the folders @Box293 mentioned.
you could move mrtg files - a better question is, do you need to.
moving files to ramdisk will help by improving performance. typically, files that are accessed a lot with r/w make good candidates as the IO performance will improve greatly.
Re: How to tell if a RamDisk is being used as expected
Posted: Fri Jan 10, 2020 3:08 pm
by tgriep
That is correct, files are created on the Ramdisk, processes and removed very quickly and it is not used to store files on a permanent basis.
The largest files on the ramdisk are the objects.cache and the status.dat and the size of those are determined by the number of checks.
I would not move the MRTG files to the ramdisk as they are used in the Bandwidth Usage report.
By nature, the files are stored in ram so if you reboot, they are gone forever.