As a general guideline, plan to have one HADB node for each CPU in the system. For example, use two HADB nodes for a machine that has two CPUs.
If you have more than one HADB node per machine (for example, if you are using bigger machines), then you must ensure that there is enough redundancy and scalability on the machines; for example multiple uninterruptible power supplies and independent disk controllers.
Alternatively, use the following procedure.
Determine the following parameters:
Maximum number of concurrent users, n_{users}.
Average BLOB size, s.
Maximum transaction rate per user, referred to as NTPS.
Determine the size in Gigabytes of the maximum primary data volume, V _{data}.
Use the following formula:
V_{data} = n_{users}^{ .} s
Determine the maximum HADB data transfer rate, R _{dt}.
This reflects the data volume shipped into HADB from the application side. Use the following formula:
R_{dt} = n_{users}^{ .} s ^{ .} NTPS
Determine the number of nodes, N _{NODES,}.
Use the following formula:
N_{NODES} = V_{data} /5GB
Round this value up to an even number, since nodes work in pairs.