SCM can be used to run virtual machines for Scyld ClusterWare, Penguin Computing’s cluster management software suite. ClusterWare is traditionally run on physical nodes, often with one single node acting as the master node. Running ClusterWare on virtual nodes presents a lot of advantages:
- Ability to “right-size” the head node. No wasted capacity or propensity to over-provision.
- Ability to live-migrate the head node when the host needs maintenance. Less down time.
- Ability to easily snap-shot the head node disk. Backups can be exported and stored, or snapshots can be rolled back to.
- Easier to run multiple head nodes in “multi-master” mode. No need to purchase additional hardware for a second head node.
In addition to running multiple head nodes, SCM makes it easier to provision additional management nodes for things like schedulers (i.e. Maui or MOAB). Here is a figure that shows a typical SCM deployment with ClusterWare:
This diagram does not show the SCM controller nodes, only the VM hosts. In order to protect the head nodes against VM host failure, it is important to ensure that each head node is on a different VM host.