A fan-out ratio is the relationship in quantity between a single port on a storage device and the
number of servers
that are attached to it.
It is important to know the fan-out ratio in a storage area network (SAN ) design so
that each server gets optimal access to storage resources. When the fan-out ratio is high and the
storage array becomes
performance will be affected negatively. Too low a low fan-out ratio, however, results in an
uneconomic use of storage.
Key factors in deciding the optimum fan-out ratio are server host bus adapter (HBA) queue depth,
storage device input/output (IOPS)
and port throughput.
This was last updated in March 2012
Contributor(s): Antony Adshead