Syncrepl connections failing

["John Kane" <john.kane@prodeasystems.com>]

I am having a problem with what appears (to me) to be 'stale' TCP
connections for syncrepl between the master and a pair of slaves.  After
restarting all, I see changes on the master replicated to both slaves.
BUT, if I wait about 30 minutes or more, then make a change, the
replication fails (most of the time).  netstat on the LDAP port show the
connections still established, but queued packets at the master server.
After about 15 minutes, the master server drops the connection.  An
overnight tcpdump on the master showed LDAP occasionally sending a
keep-alive, with 2hrs between the keep-alive messages (these keep-alives
are inconsistent, though, some nights I see none).   

I am running Red Hat EL5 and Openldap 2.3.43 on all servers with no TLS
or SASL (in our integration/test facility). 

I don't see anything in the documentation pertaining to keep-alives,
other than ITS#4708 for 2.3.38.

Here's the syncrepl for one slave:

syncrepl        rid=004
                type=refreshAndPersist
                provider=ldap://172.24.1.191
                retry="30 10 300 3"
                searchbase="o=partner_x,dc=ourcompany-int,dc=net"
                filter="(objectClass=*)"
                scope=sub
                schemachecking=off
                bindmethod=simple
                binddn="cn=syncRepl,o=partner_x,dc=ourcompany-int,dc=net
"
                credentials="secret"
updateref       ldap://172.24.1.191


The other slave's slapd.conf is indentical except rid=002. 

On the master I have:

overlay syncprov
syncprov-checkpoint 100 30
syncprov-sessionlog 100


Note:  The 2 slaves are running on blades in an IBM chassis, and the
master is on a 1U Linux server, just 'one-hop' away.   Prior to this,
when I had a master/slave pair running on the blades, syncRepl was
working fine for several months.  It was not until I moved the master to
the another server did the failures start. 

Thanks in advance for any help or info.

John Kane



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