They are usually more widely distributed than databases. Data distribution is a fundamental factor in designing directories, thereby allowing flexibility in designing centralized or completely distributed management solutions. Compared with databases, which only support a very small number of replicas, directories support replication on a much larger scale. Replication can be used to provide system fault tolerance and to design a large-scale CNM service. By locating replicas close to customers accessing the service, network latency of directory requests is decreased while the number of users supported by the system is amplified.
Directories usually have very different performance characteristics than databases.
Databases typically handle hundreds of transactions per second while directories typically handle thousands or tens of thousands of queries per second. Support for standards is important in directories, less so in databases. For example, LDAP allows the decoupling of directory clients from directory servers. It allows an LDAP client, embedded in an IP services switch, to speak with any LDAP directory server. The LDAP directory not only stores customer, provisioning and configuration information, but also contains a registry of all system components and distributed processes.