[one-users] if two system datastore are assigned to one cluster, is it working?

Carlos Martín Sánchez cmartin at opennebula.org
Mon Jul 28 03:22:15 PDT 2014


On Wed, Jul 23, 2014 at 5:49 AM, cmcc.dylan <dx10years at 126.com> wrote:

> Hi everyone!
>    if  i have two system datastore with different type, for example, one
> is ssh and the other is shared.  As i known, one cluster is allowed to
> configure multipule system datastore.  so in my case, I assign a ssh system
> datastore(id is 100) and a shared system datastore(id is 101) to one
> cluster.  when  i chose a image of one datastore to create vm instance, how
> does opennebula to chose which datastore?  Can someone show me the code in
> opennebula?

This is explained in the scheduler docs [1]:

The match-making algorithm works as follows:
> - Each disk of a running VM consumes storage from an Image Datastore. The
> VMs that require more storage than there is currently available are
> filtered out, and will remain in the ‘pending’ state.

- Those hosts that do not meet the VM requirements (see the
> SCHED_REQUIREMENTS attribute) or do not have enough resources (available
> CPU and memory) to run the VM are filtered out (see below for more
> information).
> - The same happens for System Datastores: the ones that do not meet the DS
> requirements (see the SCHED_DS_REQUIREMENTS attribute) or do not have
> enough free storage are filtered out.
> - The SCHED_RANK and SCHED_DS_RANK expressions are evaluated upon the Host
> and Datastore list using the information gathered by the monitor drivers.
> Any variable reported by the monitor driver (or manually set in the Host or
> Datastore template) can be included in the rank expressions.
> - Those resources with a higher rank are used first to allocate VMs.

By default, the sched.conf file comes with DEFAULT_DS_SCHED set to 1,
striping. The VMs are sent to the DS with more free storage.


[1] http://docs.opennebula.org/4.6/administration/references/schg.html

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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