Hello to the list, I'm trying to configure the slapd-meta OpenLDAP backend on an online cn=config configuration with no luck. Slapd version is 2.4.39 (the maximum I can achieve on the target machines building from vanilla source). The documentation is clear but too concise for me so I will try to explain what I'm trying to do to see if there is anybody that can help me. Currently I have 3 slapd servers that share a common root for the DIT, i.e.: dc=loc1,dc=root dc=loc2,dc=root dc=loc3,dc=root What I would like to achieve is to obtain a fourth server that contains the previous trees, along with its own tree, i.e. a server that contains: dc=loc0,dc=root (locally hosted data) dc=loc1,dc=root (coming from the first server, chasing referrals) dc=loc2,dc=root (coming from the second server, chasing referrals) dc=loc3,dc=root (coming from the third server, chasing referrals) this way, all the clients connecting to this server will be able to retrieve data also from the other three remote servers. As far as I understood, I only need to configure the "loc0" server to access the other three servers and get the data to serve to clients. I have already configured the fourth server with its local DIT and this is the configuration: # cat 'cn=config.ldif' dn: cn=config objectClass: olcGlobal cn: config olcArgsFile: /var/run/slapd/slapd.args olcPidFile: /var/run/slapd/slapd.pid structuralObjectClass: olcGlobal creatorsName: cn=config olcServerID: 1 olcThreads: 32 olcToolThreads: 8 olcRequires: LDAPv3 olcConnMaxPendingAuth: 100 olcTLSCACertificateFile: /etc/ssl/certs/my_ca_cert.pem olcTLSCertificateFile: /etc/ssl/certs/this-host_x509_cert.pem olcTLSCertificateKeyFile: /etc/ssl/private/this-host_x509_key.key olcTLSVerifyClient: try olcTimeLimit: 600 olcLogLevel: stats2 sync [...] # cat 'cn=module{0}.ldif' dn: cn=module{0} objectClass: olcModuleList cn: module{0} olcModulePath: /usr/lib/ldap olcModuleLoad: {0}back_hdb olcModuleLoad: {1}syncprov olcModuleLoad: {2}accesslog structuralObjectClass: olcModuleList [...] Schema files are the following: cn={0}core.ldif cn={1}cosine.ldif cn={2}nis.ldif cn={3}inetorgperson.ldif cn={4}dyngroup.ldif cn={5}kerberos.ldif # cat 'olcDatabase={1}hdb.ldif' dn: olcDatabase={1}hdb objectClass: olcDatabaseConfig objectClass: olcHdbConfig olcDatabase: {1}hdb olcDbDirectory: /var/lib/ldap olcSuffix: dc=loc0,dc=root olcAccess: {0}to attrs=userPassword,shadowLastChange,krbPrincipalKey by dn="cn =admin,dc=loc0,dc=root" write by anonymous auth by self write by * none olcAccess: {1}to dn.base="" by * read olcAccess: {2}to * by dn="cn=admin,dc=loc0,dc=root" write by * read olcLastMod: TRUE olcRootDN: cn=admin,dc=loc0,dc=root olcRootPW:: xxxxxxxxxxxxxxxxxxxx olcDbCacheSize: 10000 olcDbCheckpoint: 512 10 olcDbConfig: {0}set_cachesize 0 524288000 1 olcDbConfig: {1}set_lk_max_objects 1500 olcDbConfig: {2}set_lk_max_locks 1500 olcDbConfig: {3}set_lk_max_lockers 1500 olcDbConfig: {4}set_flags DB_LOG_AUTOREMOVE olcDbIDLcacheSize: 30000 olcDbIndex: default pres,eq [...] structuralObjectClass: olcHdbConfig olcSyncrepl: {0}rid=0 provider=ldap://second-host.loc0.root bindmethod=s imple binddn="cn=admin,dc=loc0,dc=root" credentials=xxxxxx searchbase="dc=loc0,dc=root" logbase="cn=accesslog" logfilter="(&(objectClass=auditWriteObj ect)(reqResult=0))" schemachecking=on type=refreshAndPersist retry="60 +" syn cdata=accesslog starttls=yes olcMirrorMode: TRUE [...] On top of this DB I have the "syncprov" and the "accesslog" overlays configured (these are two servers in "MirrorMode", configured following the OpenLDAP admin documentation). I believe this DB is the ones containing the actual "loc0" DIT data... Then I have the accesslog DB for the replica (with the syncprov overlay on top): # cat 'olcDatabase={2}hdb.ldif' dn: olcDatabase={2}hdb objectClass: olcDatabaseConfig objectClass: olcHdbConfig olcDatabase: {2}hdb olcDbDirectory: /var/lib/ldap/accesslog olcSuffix: cn=accesslog olcRootDN: cn=admin,dc=loc0,dc=root olcDbConfig: {0}set_cachesize 0 524288000 1 olcDbConfig: {1}set_lk_max_objects 1500 olcDbConfig: {2}set_lk_max_locks 1500 olcDbConfig: {3}set_lk_max_lockers 1500 olcDbConfig: {4}set_flags DB_LOG_AUTOREMOVE olcDbIndex: default eq olcDbIndex: entryCSN,objectClass,reqEnd,reqResult,reqStart [...] On top of this environment I start loading the needed modules with this LDIF file: version: 1 dn: cn=module{0},cn=config changetype: modify add: olcModuleLoad olcModuleLoad: back_ldap - add: olcModuleLoad olcModuleLoad: back_meta - add: olcModuleLoad olcModuleLoad: rwm and it seems I'm able to load the new modules without errors into the configuration, thus I obtain: # cat 'cn=module{0}.ldif' dn: cn=module{0} structuralObjectClass: olcModuleList objectClass: olcModuleList cn: module{0} olcModulePath: /usr/lib/ldap olcModuleLoad: {0}back_hdb olcModuleLoad: {1}syncprov olcModuleLoad: {2}accesslog olcModuleLoad: {3}back_ldap olcModuleLoad: {4}back_meta olcModuleLoad: {5}rwm [...] Now I try to load the slapd-meta directives into a new database using this LDIF: version: 1 dn: olcDatabase={3}meta,cn=config objectClass: olcDatabaseConfig objectClass: olcMetaConfig olcDatabase: {3}meta olcSuffix: dc=root olcDbURI: "ldap://server-loc1.loc1.root/dc=loc1,dc=root" olcDbIdAssertBind: bindmethod=simple binddn="cn=admin,dc=loc1,dc=root" credentials=xxxxxx starttls=yes tls_reqcert=demand olcDbURI: "ldap://server-loc2.loc2.root/dc=loc2,dc=root" olcDbIdAssertBind: bindmethod=simple binddn="cn=admin,dc=loc2,dc=root" credentials=xxxxxx starttls=yes tls_reqcert=demand olcDbURI: "ldap://server-loc3.loc3.root/dc=loc3,dc=root" olcDbIdAssertBind: bindmethod=simple binddn="cn=admin,dc=loc3,dc=root" credentials=xxxxxx starttls=yes tls_reqcert=demand but I obtain an error that sticks me trying various combinations without success: # ldapadd -Y EXTERNAL -H ldapi:/// -f slapd-META-DB-CREATION.ldif SASL/EXTERNAL authentication started SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth SASL SSF: 0 adding new entry "olcDatabase={3}meta,cn=config" ldap_add: Object class violation (65) additional info: attribute 'olcDbURI' not allowed and: # tail /var/log/openldap/slapd.log Nov 9 19:47:17 server01 slapd[32392]: conn=1025 op=2 ENTRY dn="dc=loc0,dc=root" Nov 9 19:47:29 server01 slapd[32392]: conn=1052 op=2 INTERM oid=1.3.6.1.4.1.4203.1.9.1.4 Nov 9 19:49:47 server01 slapd[32392]: conn=1327 op=2 ENTRY dn="dc=loc0,dc=root" Nov 9 19:52:17 server01 slapd[32392]: conn=1628 op=2 ENTRY dn="dc=loc0,dc=root" Nov 9 19:54:46 server01 slapd[32392]: conn=1929 op=2 ENTRY dn="dc=loc0,dc=root" Nov 9 19:57:07 server01 slapd[32392]: Entry (olcDatabase={3}meta,cn=config), attribute 'olcDbURI' not allowed Into the slapd-meta documentation the "URI" directive is mentioned but the "DbURI" seems to raise a "better error", in fact if I try to modify the above LDIF file using "URI" I obtain: SASL/EXTERNAL authentication started SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth SASL SSF: 0 adding new entry "olcDatabase={3}meta,cn=config" ldap_add: Undefined attribute type (17) additional info: olcUri: attribute type undefined Moreover, it is not stated into the slapd-meta docs that the slapd-ldap backend is needed by slapd-meta but, anyway, I think its needed because if I try to load the slapd-meta alone it raises an error (I don't remember exactly which one). At this point I'm stuck to this error and I wasn't able to find any hint on the web to solve this :( The examples I was able to find were related with the static slapd.conf configuration, I counldn't find any "full" configuration example using the cn=config. I'm wondering if I should create a "cn=root" actual DB first and then link the sub-DITs to it, or, maybe, add some other overlay... I really can't understand how it should work :( Can please anybody help me? Thank you very much