[Ovirt-devel] Enumerating node information to the WUI

[Perry N. Myers]

Chris Lalancette wrote:
> Darryl L. Pierce wrote:
>> MEM: We currently return the total system memory reported but should 
>> probably also grab the free memory after the managed node image is loaded.
> 
> Unfortunately, the free memory number is basically useless, since Linux is going
> to be using lots of memory for page cache pages in the future.  Not something I
> think we need to track.  We *do* need to track (in the database) how much memory
> we have given to VMs over on a particular machine so we don't load it up too
> much, but free memory on the machine itself is not this number.

I agree that reporting free memory is not so good.  But it might be useful 
to detect how much memory the managed node is taking and subtract that 
from the total memory of the system.  i.e. Box has 2GB RAM.  Managed Node 
is taking approx 200MB.  Leaving a system with 1.8GB free for starting VMs.

As you work with systems that have larger amounts of RAM, the 200MB 
footprint of the Managed Node becomes less of a concern, but I'm sure 
there will be people running on 2 and 4GB systems.

This also might be important for when we support Xen/dom0.  The box might 
have XGB of RAM, but dom0 needs at least XMB to run properly.  So we 
should take that into account right?

>> DISK: Returning the physical and logical partitions with free space 
>> available.
> 
> Hard to say.  We've been going with the idea of totally diskless machines until
> now, with totally remote storage.  That being said, if we are going to support
> other things in the future (like Xen), we will need some sort of stuff for
> disks.  This needs more thought; I would punt on this one for now until we
> better understand our requirements for local disks.

Agreed.  We can punt for now, but the use case in the future would be 
something like...

Detect all mounted partitions (mount point, total size, free space... 
basically df).  Send that information and the WUI user can use this to 
determine where to put a file based image on the filesystem.  In addition, 
reporting of LVM volumes would be useful as well so VMs could be created 
with local LVM.  I don't think we want to go into partitioning up LVM 
volumes or new ext3 partitions via the WUI.  That is a task best left to 
other interfaces/tools.

Perry

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