cm_processes question

[#1]

My understanding of the cm_processes tmpfs is that it is for issues on systems where /var is a no ext mount. We are running on RHEL 6.5 and /var is ext4. Is there a way to prevent CM from mounting this filesystem or, if not, adjusting its size? 

Thanks

[#2 · Accepted solution]

Hi Greg,

It's required for distros where /var/run is mounted noexec but we use it unconditonally so that the Agent is operating in a consistent environment across all distros, and certain bits of agent functionality take advantage of this (such as our logic for cleaning out /var/run/cloudera-scm-agent, which unmounts and remounts the tmpfs).

What is your concern? Do you have a particular problem you are trying to solve?

Thanks,

[#3]

Our OS team was asking about this because they saw the tmpfs filesystem allocated to 50% of memory. We weren't able to find a lot of documentation on it and were trying to determine if it was necessary and if so why. This has not caused any issues. I will pass the information along. Thanks.

[#4]

A tmpfs will default to a max size of 50% of physical RAM but this space is not allocated until its used, and tmpfs will be paged out to swap if there is memory pressure.

[#5]

you could also resize the mountpoint if you think it is oversized.

sudo mount -o size=10G -o remount cm_processes.

After I resize from 71GB to 10GB, I don't find any different in "free -h". So I feel the tmpfs doesn't really block the physical memory ahead.

Taken from following reference.

http://man7.org/linux/man-pages/man5/tmpfs.5.html

rgds,
Rama.