We recommend a minimum cluster size of five nodes for all single node chassis, and four nodes for all quad node chassis, even if you are not writing to all of them. For example, if you are implementing a four-node Recorder solution, implement a five -node cluster. This also meets the recommended best practices for data protection.
To estimate the ideal number of nodes in a cluster, you need to consider cluster bandwidth and capacity.
- Sizing by bandwidth
- We recommend a cluster size with one or more additional nodes than calculated in bandwidth sizing. This ensures that failover of a node allows for redistribution of NAS connections and avoids any frame loss.
- Sizing by aggregate capacity
- We recommend a cluster size with enough usable capacity to handle 110 percent of the calculated space requirement, with a minimum added capacity of one full node plus 10 percent. The values are based on camera bit rate.
The Isilon sizing tool can use both the sizing by bandwidth and sizing by aggregate capacity methods when calculating ideal cluster size.