nsslapd-counters attribute enabled counters to run. However, running counters can affect performance, so it also possible to turn off counters. If counters are off, they all have a value of zero (0).
By default, counters are already enabled. To enable or disable performance counters, use
ldapmodify -D "cn=directory manager" -W -p 389 -h server.example.com -x
Regardless of the whether the Directory Server is run on a 32-bit or 64-bit platform, the server itself records many counter values using 64-bit integers. For high-traffic sites, 32-bit counters turn over too quickly, which leads to quirky ratios and counts. Using 64-bit integers (on all platforms) improves performance and enables administrators to gather long-term statistics accurately.