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Re: Syncrepl of portions of glued database - problems (in HEAD)

Pierangelo Masarati wrote:

I'm trying to set up a tutorial about syncreplication of portions of glued databases, and I found it very tricky to determine what sequence each brick must be stacked to get it work. I'm working with HEAD, so there might some issue with syncrepl provider features being provided by the syncprov overlay, and with the glue feature being provided by the glue overlay.

The setup is (without non-essential details; mostly cut'n'pasted from tests 012 and 018):

<DSA1 slapd.conf>
database bdb
suffix "ou=Information Technology Division,ou=People,dc=example,dc=com"
directory ./testrun/db.1.a
rootdn "cn=Manager 1,dc=example,dc=com"
index objectclass eq
overlay syncprov

database        bdb
suffix          "ou=Groups,dc=example,dc=com"
directory       ./testrun/db.1.b
rootdn          "cn=Manager 1,dc=example,dc=com"
index           objectclass     eq
syncrepl        rid=1
               provider=ldap://:9012
               binddn="cn=Manager 2,dc=example,dc=com"
               bindmethod=simple
               credentials=secret
               searchbase="ou=Groups,dc=example,dc=com"
               filter="(objectClass=*)"
               attrs="*,+"
               schemachecking=off
               scope=sub
               type=refreshAndPersist
               retry="10 3 300 +"
updateref       ldap://:9012
overlay         syncprov

database bdb
suffix "dc=example,dc=com"
directory ./testrun/db.1.c
rootdn "cn=Manager 1,dc=example,dc=com"
rootpw secret
index objectclass eq
overlay syncprov
overlay glue
glue-sub "ou=Information Technology Division,ou=People,dc=example,dc=com"
glue-sub "ou=Groups,dc=example,dc=com"
</DSA1 slapd.conf>

<DSA2 slapd.conf>
database bdb
suffix "ou=Information Technology Division,ou=People,dc=example,dc=com"
directory ./testrun/db.2.a
rootdn "cn=Manager 2,dc=example,dc=com"
index objectclass eq
syncrepl rid=1
provider=ldap://:9011
binddn="cn=Manager 1,dc=example,dc=com"
bindmethod=simple
credentials=secret
searchbase="ou=Information Technology Division,ou=People,dc=example,dc=com"
filter="(objectClass=*)"
attrs="*,+"
schemachecking=off
scope=sub
type=refreshAndPersist
retry="10 3 300 +"
updateref ldap://:9011
overlay syncprov

database        bdb
suffix          "ou=Groups,dc=example,dc=com"
directory       ./testrun/db.2.b
rootdn          "cn=Manager 2,dc=example,dc=com"
index           objectclass     eq
overlay         syncprov

database bdb
suffix "dc=example,dc=com"
directory ./testrun/db.2.c
rootdn "cn=Manager 2,dc=example,dc=com"
rootpw secret
index objectclass eq
overlay syncprov
overlay glue
glue-sub "ou=Information Technology Division,ou=People,dc=example,dc=com"
glue-sub "ou=Groups,dc=example,dc=com"
</DSA2 slapd.conf>

All databases need to have the syncprov overlay installed to recognize the LDAP Sync control; however, it appears that the presence of the glue overlay prohibits the replication to occur as expected (there's also a chicken and egg problem of what server is starting first; for the purpose I had to add the retry statement to the syncrepl).

The "overlay syncprov" in the glue database must appear __before__ the "overlay glue", otherwise I get "findbase failed! 32". If there is no "overlay syncprov" in the glue database, it fails because the control appears to be unsupported by the glue database. With this configuration, if the system starts with the glue database set up, and with the shadow databases empty, the synchronization occurs as expected. Owever, further updates are not sync'ed; same with refreshOnly.

Since this setup is very important for us (it allows to implement detached updates in a context in which each DSA is master for its own data and resync as soon as connection is back), I think this feature should always be available regardless of the software development. As such, I think I should commit a test for it, which is likely to be a rather transversal case, i.e. it requires the simultaneous availability of different features.

I had this working when I first wrote the glue overlay, but that was before the backend control handling was modified. Should be an easy enough fix...

--
 -- Howard Chu
 Chief Architect, Symas Corp.       Director, Highland Sun
 http://www.symas.com               http://highlandsun.com/hyc
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