--On Thursday, October 22, 2009 4:34 PM -0400 Sam Tran stlist@gmail.com wrote:

Hi All,

I am looking to upgrade our OL 2.3 platform to OL 2.4.

For all write operations, I'd like to have two masters in Mirror Mode configuration and behind a load balancer with a virtual IP (VIP) address. All read operations will be performed on a set of replicas. The replication mode would be delta-syncrepl. I am trying to figure out how to configure replication between the replicas and the masters. I came across those two threads that seem to address this issue:

http://www.openldap.org/lists/openldap-devel/200903/msg00085.html http://www.openldap.org/lists/openldap-software/200903/msg00127.html

If I understand correctly, there are two possible configurations:

1. On each replica, create a single syncrepl stanza that points to the

load balancer VIP.

2. On each replica, creates two syncrepl stanzas, each one pointing to

a different master.

Could you please confirm that both configurations would work? Should the second configuration be favored over the first for it does not depend on the load balancer?

I don't know the answer, but let me know when you figure it out. ;) I'd guess the first option would be best, since only one master will be receiving the writes as well, since you'll be using mirror mode.

--Quanah

--

Quanah Gibson-Mount Principal Software Engineer Zimbra, Inc -------------------- Zimbra :: the leader in open source messaging and collaboration

On Thu, Oct 22, 2009 at 4:34 PM, Sam Tran stlist@gmail.com wrote:

Hi All,

I am looking to upgrade our OL 2.3 platform to OL 2.4.

For all write operations, I'd like to have two masters in Mirror Mode configuration and behind a load balancer with a virtual IP (VIP) address. All read operations will be performed on a set of replicas. The replication mode would be delta-syncrepl. I am trying to figure out how to configure replication between the replicas and the masters. I came across those two threads that seem to address this issue:

http://www.openldap.org/lists/openldap-devel/200903/msg00085.html http://www.openldap.org/lists/openldap-software/200903/msg00127.html

If I understand correctly, there are two possible configurations:

1. On each replica, create a single syncrepl stanza that points to the

load balancer VIP.

[snip]

I have started replication using the first configuration where the consumer has a single syncrepl stanza pointing to the load balancer Virtual IP address (VIP):

syncrepl rid=012 provider=ldaps://vip.example.com:636 bindmethod=simple binddn="cn=syncrepl,ou=Accounts,ou=Apps,dc=example,dc=com" credentials=xxxxxxxxxxxxxxxxx type=refreshAndPersist retry="5 +" searchbase="dc=example,dc=com" logbase="cn=accesslog" logfilter="(&(objectClass=auditWriteObject)(reqResult=0))" schemachecking=on syncdata=accesslog

I have two providers, A and B, configured in Mirror Mode behind the VIP (vip.example.com). Write operations are performed on the provider that hold the VIP at a given time.

The consumer got its initial content load when provider A had the VIP. Any subsequent updates on the provider that holds the VIP were replicated to the consumer.

I then manually migrated the VIP from provider A to provider B to simulate a failover. Any updates on the provider that holds the VIP were not replicated to the consumer unless I manually restarted the consumer. Here are the resulting logs on the consumer:

Oct 28 11:35:22 info-ldap-012 slapd[12157]: slapd starting Oct 28 11:35:22 info-ldap-012 slapd[12157]: do_syncrep2: rid=012 LDAP_RES_SEARCH_RESULT Oct 28 11:35:22 info-ldap-012 slapd[12157]: do_syncrep2: rid=012 (4096) Content Sync Refresh Required Oct 28 11:35:22 info-ldap-012 slapd[12157]: do_syncrep2: rid=012 LDAP_RES_INTERMEDIATE - SYNC_ID_SET Oct 28 11:35:22 info-ldap-012 last message repeated 16 times Oct 28 11:35:22 info-ldap-012 slapd[12157]: syncrepl_entry: rid=012 LDAP_RES_SEARCH_ENTRY(LDAP_SYNC_ADD) Oct 28 11:35:22 info-ldap-012 slapd[12157]: syncrepl_entry: rid=012 be_search (0) Oct 28 11:35:22 info-ldap-012 slapd[12157]: syncrepl_entry: rid=012 uid=st,ou=People,dc=example,dc=com Oct 28 11:35:22 info-ldap-012 slapd[12157]: syncrepl_entry: rid=012 be_modify uid=st,ou=People,dc=example,dc=com (0) Oct 28 11:35:22 info-ldap-012 slapd[12157]: do_syncrep2: rid=012 LDAP_RES_SEARCH_RESULT Oct 28 11:35:22 info-ldap-012 slapd[12157]: do_syncrep2: cookie=rid=012,sid=00b,csn=20090721190743.568481Z#000000#000#000000;20091028153356.906 892Z#000000#00a#000000;20091028153507.836516Z#000000#00b#000000 Oct 28 11:35:22 info-ldap-012 slapd[12157]: nonpresent_callback: rid=012 present UUID edbbfcd6-c629-1029-9d11-9eba13a1da21, dn dc=example,dc=com Oct 28 11:35:22 info-ldap-012 slapd[12157]: nonpresent_callback: rid=012 present UUID edda076c-c629-1029-9d12-9eba13a1da21, dn cn=manager,dc=example,dc=com [snip] Oct 28 11:35:22 info-ldap-012 slapd[12157]: slap_queue_csn: queing 0x12c1fb20 20091028153507.836516Z#000000#00b#000000 Oct 28 11:35:22 info-ldap-012 slapd[12157]: slap_graduate_commit_csn: removing 0x12d959f0 20091028153507.836516Z#000000#00b#000000 Oct 28 11:35:22 info-ldap-012 slapd[12157]: do_syncrep2: rid=012 LDAP_RES_INTERMEDIATE - REFRESH_DELETE

However if I perform an update on provider A (even though it doesn't hold the VIP), the change is replicated to the consumer. Here are the resulting logs on the consumer:

Oct 28 11:33:56 info-ldap-012 slapd[22967]: do_syncrep2: cookie=rid=012,sid=00b,csn=20091028153356.906892Z#000000#00a#000000 Oct 28 11:33:56 info-ldap-012 slapd[22967]: slap_queue_csn: queing 0x1e7eea84 20091028153356.906892Z#000000#00a#000000 Oct 28 11:33:56 info-ldap-012 slapd[22967]: slap_graduate_commit_csn: removing 0x1e803500 20091028153356.906892Z#000000#00a#000000 Oct 28 11:33:56 info-ldap-012 slapd[22967]: syncrepl_message_to_op: rid=012 be_modify uid=st,ou=People,dc=example,dc=com (0) Oct 28 11:33:56 info-ldap-012 slapd[22967]: slap_queue_csn: queing 0x1e7eeff0 20091028153356.906892Z#000000#00a#000000 Oct 28 11:33:56 info-ldap-012 slapd[22967]: slap_graduate_commit_csn: removing 0x1e7f0170 20091028153356.906892Z#000000#00a#000000

Is this the expected behaviour? Should I infer that delta-syncrepl does not work when the consumer is pointing to a load balancer fronting two providers in Mirror Mode configuration?

Thanks. -- Sam