This page lists best practices, grouped by area, for combining different node hardware in a cluster.
| Area | Guidance |
|---|---|
| RAM | Adding a single node with a larger RAM footprint than the rest of the cluster can create undesirable scenarios for VM failover and rolling software upgrades. |
| CPU | Mixing CPU generations in a cluster (e.g., adding Broadwell nodes to a Skylake cluster) causes the cluster to present the lowest common denominator CPU feature set for workload migration and failover compatibility. VMs typically need to be shut down and restarted to recognize a different CPU model after a node addition, so failover and live migration work correctly. |
| Networking | Match networking capabilities across all nodes. 1GbE ports are disabled for system use on all 10GbE SFP+ node models and cannot be enabled. 10GbE SFP+ connections are not supported with transceivers used to convert them to any other speed. |
| Tiering | Tiered nodes with fewer than 3 SSDs are unsupported for use as an SNS (see Single Node Systems (SNS)). |
| Edge | The HE100 and HE200 series cannot be combined with any other node type. |
| GPU | GPU nodes support single-node or clustered configurations, but cannot be combined with any other node type or any GPU node outside their exact line. |
| Capacity | Each storage pool (SSD and HDD) on a single node being added to a cluster must not exceed the entire cluster’s existing storage pool capacity for that same pool. For example, adding a single 12 TB HDD / 960 GB SSD node to a 3-node cluster of 9 TB HDD / 1.4 TB SSD nodes is not recommended, due to the HDD pool size mismatch — even though the SSD pool size would meet the recommendation. |
| Mixing Capacity Storage Pools | 30% of the SSD tier is reserved by default for write bursts (new system writes). Factor this into capacity planning. For large data migrations, Scale Computing Support can temporarily disable tiering behavior that might otherwise cause performance issues. VM snapshots and VM imports are sent directly to the HDD tier for capacity and performance reasons. |
| Performance | HDD pool performance is roughly determined by the capacity and speed of the available drives. Mixing drive speeds and capacities within a tier is supported but inadvisable — performance issues can be compounded when higher-capacity, slower drives are added to a 10K or 15K speed system. Contact your Sales Engineer with questions about a specific use case. |
See Node Lifecycle Management for the steps to add or remove a node once you’ve confirmed compatibility.