validate free memory on minions

[jschmid1]

librados will return 1, can't fill zero pages, if your machine has not enough(<= 50mb) memory left.

ran into this on a VM setup some time back. Implementing a validation as part of a (custom)grain could be helpful

[BlaineEXE]

Is there a way we can not hardcode the 50mb number? Can Ceph output the amount of memory it needs to fulfill librados requests that we could store that as a grain?

Even if we do have to hardcode, it would be nice to warn the user that they are getting low on memory before they get critically low.

[jschmid1]

I think this doesn't limit to librados calls, but to all commands that will be executed on minions.
So having salt telling the user that minions are short on memory would be a benefit

[tserong]

How much RAM was allocated to the VM in total? I tend to run into trouble with anything less than 2GB. Also, this is probably more an issue for dev/test, where we might be using tiny machines, than for "real" deployments, right?

[jschmid1]

How much RAM was allocated to the VM in total?

2GB

I think this is not only limited to dev/test env. That is just one of these checks we should do before executing certain tasks in order to avoid undefined behavior. The ideal solution would be ofc to passthrough the exception that librados throws, but imho we can't solely rely on salt here.

[swiftgist]

To address this issue, maybe a man page for odd, cryptic errors.