[one-users] Local system datastores and free space monitoring

[Carlos Martín Sánchez]

Hi,

On Mon, Sep 22, 2014 at 12:18 PM, Pentium100 <pentium100 at gmail.com> wrote:

> Hello,
>
> I am testing OpenNebula with local storage (local SSDs are faster than
> shared storage), however, I do not understand how (and if) OpenNebula
> monitors the available free space in each hypervisor.
>
> Let's say I add "filesystem" datastore with "ssh" TM. It looks to me like
> only the free space on the control node is monitored, while hoping the the
> hypervisors have enough space on them. So, if one HV has some resources
> left but the storage is full how will it know not to create new VMs there?
>
> Now, I could add each hypervisor as a separate datastore, but I do not see
> a way to associate "data store X is dedicated to hypervisor X", or
> OpenNebula would try to create VMs on HV1 with storage on HV2.
>
> Is there a way to make OpenNebula monitor each hypervisor and its free
> space?
>

OpenNebula is already monitoring the ssh (local) datastores. The
information is gathered by the host monitoring probes (IM drivers), and is
stored inside each host resource. What may be a bit confusing is that you
need to go to the individual host information (through sunstone or with
onehost show) to see the local datastore free space. And, of course, the
scheduler uses this information to determine if a VM will fit in a host
before deploying it.

There is one more detail worth mentioning. Before the datastore dir is
created (e.g. /var/lib/one/datastores/100), the monitorization will provide
information for the parent directory. So it may happen that you won't see
the free space of a local datastore until the first VM is deployed there.
During this time, the scheduler also uses the parent dir free space to
determine the VM storage placement.

Best regards.
--
Carlos Martín, MSc
Project Engineer
OpenNebula - Flexible Enterprise Cloud Made Simple
www.OpenNebula.org <http://www.opennebula.org/> | cmartin at opennebula.org |
@OpenNebula <http://twitter.com/opennebula> <cmartin at opennebula.org>
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