[one-dev] Scheduler decisions regarding storage

[Stuart Longland]

On 05/06/14 12:32, Stuart Longland wrote:
> What I observe though, is that the disk storage always returns 0.  My
> plan was to expand on this by adding an extra parameter (int& cache),
> and I'd use whatever code is present to calculate disk requirements to
> figure out how much to cache and thus, calculate the cache output.

I've gone digging further back into the git repository to see if there
was previously code that calculated the disk requirements.

It seems not.  The file in question was added back in 2008, "Initial
commit of ONE code", and those lines are largely unchanged today
according to `git blame`.  So I guess it was a place-holder that never
got filled in, perhaps because it hasn't been needed until now.

The data needed on the host is going to largely depend on what kind of
datastore is being used.  Plain files using SSH for transfer is going to
require space for full images on the hosts, whereas datastores using
centralised storage won't require any (unless cached).

I think it makes sense to have the system work out an estimate for how
much storage might be needed on the host to run the VM.  Now it's a
question of do I re-use the "disk" parameter, meaning required "local
disk on host" including cache, or do I create another variable as I was
planning?

Regards,
-- 
Stuart Longland
Systems Engineer
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