slapd.backends - backends for slapd, the stand-alone LDAP daemon
The slapd(8) daemon can use a variety of different backends for serving
LDAP requests. Backends may be compiled statically into slapd, or when
module support is enabled, they may be dynamically loaded. Multiple
instances of a backend can be configured, to serve separate databases
from the same slapd server.
Configuration options for each backend are documented separately in the
corresponding slapd-<backend>(5) manual pages.
bdb This was the recommended primary backend through OpenLDAP 2.3,
but it has since been superseded by the hdb backend. It takes
care to configure it properly. It uses the transactional data-
base interface of the Oracle Berkeley DB (BDB) package to store
config This backend is used to manage the configuration of slapd at
run-time. Unlike other backends, only a single instance of the
config backend may be defined. It also instantiates itself auto-
matically, so it is always present even if not explicitly
defined in the slapd.conf(5) file.
dnssrv This backend is experimental. It serves up referrals based upon
SRV resource records held in the Domain Name System.
hdb This is the recommended primary backend for a normal slapd data-
base. hdb is a variant of the bdb backend that uses a hierar-
chical database layout. This layout stores entry DNs more effi-
ciently than the bdb backend, using less space and requiring
less work to create, delete, and rename entries. It is also one
of the few backends to support subtree renames.
ldap This backend acts as a proxy to forward incoming requests to
another LDAP server.
ldif This database uses the filesystem to build the tree structure of
the database, using plain ascii files to store data. Its usage
should be limited to very simple databases, where performance is
not a requirement. This backend also supports subtree renames.
mdb This will soon be the recommended primary backend, superseding
hdb. This backend uses OpenLDAP's own MDB transactional data-
base library. It is extremely compact and extremely efficient,
delivering much higher performance than the Berkeley DB backends
while using significantly less memory. Also, unlike Berkeley
DB, MDB is crash proof, and requires no special tuning or main-
tenance. This backend also supports subtree renames.
meta This backend performs basic LDAP proxying with respect to a set
of remote LDAP servers. It is an enhancement of the ldap back-
This backend provides information about the running status of
the slapd daemon. Only a single instance of the monitor backend
may be defined.
ndb This backend is experimental. It uses the transactional data-
base interface of the MySQL Cluster Engine (NDB) to store data.
Note that Oracle, which now owns MySQL, has withdrawn support
for NDB and this backend is unlikely to be developed any fur-
null Operations in this backend succeed but do nothing.
passwd This backend is provided for demonstration purposes only. It
serves up user account information from the system passwd(5)
perl This backend embeds a perl(1) interpreter into slapd. It runs
Perl subroutines to implement LDAP operations.
relay This backend is experimental. It redirects LDAP operations to
another database in the same server, based on the naming context
of the request. Its use requires the rwm overlay (see
slapo-rwm(5) for details) to rewrite the naming context of the
request. It is primarily intended to implement virtual views on
databases that actually store data.
shell This backend executes external programs to implement LDAP opera-
tions. It is primarily intended to be used in prototypes.
sql This backend is experimental. It services LDAP requests from an
default slapd configuration file
default slapd configuration directory
ldap(3), slapd-bdb(5), slapd-config(5), slapd-dnssrv(5), slapd-hdb(5),
slapd-ldap(5), slapd-ldif(5), slapd-mdb(5), slapd-meta(5), slapd-moni-
tor(5), slapd-ndb(5), slapd-null(5), slapd-passwd(5), slapd-perl(5),
slapd-relay(5), slapd-shell(5), slapd-sql(5), slapd.conf(5),
slapd.overlays(5), slapd(8). "OpenLDAP Administrator's Guide"
OpenLDAP Software is developed and maintained by The OpenLDAP Project
<http://www.openldap.org/>. OpenLDAP Software is derived from Univer-
sity of Michigan LDAP 3.3 Release.
OpenLDAP 2.4.36 2013/08/17 SLAPD.BACKENDS(5)
Man(1) output converted with