How does the scheduler allocate drive space on compute nodes?

asked 2013-05-16 14:47:43 -0600

quicksilvercapps gravatar image

I am new to Openstack and am trying to determine how the compute node serves local block storage to the service. For example, in hadoop, you would add locations to which you drives were mounted to the configuration files. They would then be added to the available hadoop resources for that node. In openstack the only way I see doing this is by adding all available space to the partition mounted at "/". If this is the case how would I use network storage to augment the available openstack resource pool?

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HI, how is your OpenStack cloud configured? Are you using Cinder for Block Storage/Virtual Volumes, or is it just a standard Nova/OpenStack Compute installation?

fifieldt gravatar imagefifieldt ( 2013-05-30 05:25:12 -0600 )edit

I am running Cinder, but again does that not take from the same resource pool on the compute nodes?

quicksilvercapps gravatar imagequicksilvercapps ( 2013-05-30 05:55:21 -0600 )edit

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answered 2013-06-08 22:51:12 -0600

fifieldt gravatar image


You might be interested in reading Chapter 5 Storage Decisions of the OpenStack Operations Guide:

In there, it explains the different types of storage and ways of provisioning them.

Essentially, you have:

  • /dev/vda - the expanded image, from which the operating system of the VM runs, sourced from wherever the compute node running the VM gets its /var/lib/nova/instances from
  • /dev/vdb - the ephemeral storage, which comes from /var/lib/nova/instances, like the expanded image. Size is based on VM flavor.
  • /dev/vd{c-z} - volumes that you can mount from cinder, via the API or dashboard. These come from wherever your cinder service is running - be in on the same compute node disk as the ephemeral storage, or some other external storage. You choose the size based on your quota. The actual storage used will depend on the decision in the cinder scheduler.

Hope that helps!

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Asked: 2013-05-16 14:47:43 -0600

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Last updated: Jun 08 '13