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cm_processes question

Explorer

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

1 ACCEPTED SOLUTION

Cloudera Employee

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,

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4 REPLIES 4

Cloudera Employee

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,

Explorer

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.

Cloudera Employee

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.

Explorer

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.

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