Size LDAP directory load: query rate, cache offload, result bandwidth and per-connection query rate.
Directory load is a product of client count and per-client query rate, reduced by whatever the application caches locally. Result bandwidth matters separately because broad searches returning many entries move far more data than the query count suggests. Unbounded LDAP searches are a classic outage cause: a query returning thousands of entries at hundreds of queries per second saturates both the directory's CPU and the link, even though the query rate looks modest.
LDAP Query
total qps = clients × queries per client per second; directory qps = total × (1 − cache hit ratio).
Result set bandwidth
result bandwidth = qps × entries per query × bytes per entry × 8
total qps = clients × queries per client per second; directory qps = total × (1 − cache hit ratio). Directory load is a product of client count and per-client query rate, reduced by whatever the application caches locally. Result bandwidth matters separately because broad searches returning many entries move far more data than the query count suggests.
Unbounded LDAP searches are a classic outage cause: a query returning thousands of entries at hundreds of queries per second saturates both the directory's CPU and the link, even though the query rate looks modest.
This calculator takes 6 inputs: Application clients, Queries per client per second, Entries returned per query, Bytes per returned entry, Client-side cache hit ratio, Pooled LDAP connections. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.