From ee41994407609f03e58b66d4a353681602873d23 Mon Sep 17 00:00:00 2001 From: Gavin Henry Date: Thu, 29 Nov 2007 17:52:30 +0000 Subject: [PATCH] MMR intro complete. Example to come. --- doc/guide/admin/replication.sdf | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) diff --git a/doc/guide/admin/replication.sdf b/doc/guide/admin/replication.sdf index c0ece9b758..6bd3a9cf5c 100644 --- a/doc/guide/admin/replication.sdf +++ b/doc/guide/admin/replication.sdf @@ -156,16 +156,27 @@ data to multiple Master Directory servers. * Advantages of Multi-Master replication: -- If any master fails, other masters will continue to accept updates. +- If any master fails, other masters will continue to accept updates +- Avoids a single point of failure - Masters can be located in several physical sites i.e. distributed across the network/globe. -- Good for Disaster Recovery +- Good for Automatic failover/High Availability -* Disadvantages of Multi-Master replication : +* Disadvantages of Multi-Master replication: + +- It has {{B:NOTHING}} to do with load balancing +- {{URL:http://www.openldap.org/faq/data/cache/1240.html}} +- If connectivity with a master is lost because of a network partition, then +"automatic failover" can just compound the problem +- Typically, a particular machine cannot distinguish between losing contact + with a peer because that peer crashed, or because the network link has failed +- If a network is partitioned and multiple clients start writing to each of the +"masters" then reconciliation will be a pain; it may be best to simply deny +writes to the clients that are partitioned from the single master +- Masters {{B:must}} propagate writes to {{B:all}} the other servers, which +means the network traffic and write load is constant and spreads across all +of the servers -http://www.connexitor.com/blog/pivot/entry.php?id=105#body -http://www.openldap.org/lists/openldap-software/200702/msg00006.html -http://www.openldap.org/lists/openldap-software/200602/msg00064.html This is discussed in full in the {{SECT:N-Way Multi-Master}} section below @@ -588,6 +599,9 @@ cookie stored in the consumer replica database. H2: N-Way Multi-Master +Import and expand from link: + +{{URL:http://blog.suretecsystems.com/archives/40-OpenLDAP-Weekly-News-Issue-5.html#extended}} H2: MirrorMode -- 2.39.5