diff --git a/doc/filelist.sgml b/doc/filelist.sgml index ae980054..90fc8810 100644 --- a/doc/filelist.sgml +++ b/doc/filelist.sgml @@ -54,7 +54,6 @@ - diff --git a/doc/repmgr.sgml b/doc/repmgr.sgml index a4daf9db..16cac2b9 100644 --- a/doc/repmgr.sgml +++ b/doc/repmgr.sgml @@ -84,7 +84,6 @@ &repmgrd-automatic-failover; &repmgrd-configuration; &repmgrd-operation; - &repmgrd-witness-server; &repmgrd-bdr; diff --git a/doc/repmgrd-automatic-failover.sgml b/doc/repmgrd-automatic-failover.sgml index 1521fe5d..d89b6de5 100644 --- a/doc/repmgrd-automatic-failover.sgml +++ b/doc/repmgrd-automatic-failover.sgml @@ -13,36 +13,45 @@ providing monitoring information about the state of each standby. - + repmgrd - cascading replication + witness server - cascading replication + witness server repmgrd - repmgrd and cascading replication + Using a witness server with repmgrd - Cascading replication - where a standby can connect to an upstream node and not - the primary server itself - was introduced in PostgreSQL 9.2. &repmgr; and - repmgrd support cascading replication by keeping track of the relationship - between standby servers - each node record is stored with the node id of its - upstream ("parent") server (except of course the primary server). + In a situation caused e.g. by a network interruption between two + data centres, it's important to avoid a "split-brain" situation where + both sides of the network assume they are the active segment and the + side without an active primary unilaterally promotes one of its standbys. - In a failover situation where the primary node fails and a top-level standby - is promoted, a standby connected to another standby will not be affected - and continue working as normal (even if the upstream standby it's connected - to becomes the primary node). If however the node's direct upstream fails, - the "cascaded standby" will attempt to reconnect to that node's parent - (unless failover is set to manual in - repmgr.conf). + To prevent this situation happening, it's essential to ensure that one + network segment has a "voting majority", so other segments will know + they're in the minority and not attempt to promote a new primary. Where + an odd number of servers exists, this is not an issue. However, if each + network has an even number of nodes, it's necessary to provide some way + of ensuring a majority, which is where the witness server becomes useful. + + + This is not a fully-fledged standby node and is not integrated into + replication, but it effectively represents the "casting vote" when + deciding which network segment has a majority. A witness server can + be set up using . Note that it only + makes sense to create a witness server in conjunction with running + repmgrd; the witness server will require its own + repmgrd instance. - + + + repmgrd @@ -96,4 +105,36 @@ + + + repmgrd + cascading replication + + + + cascading replication + repmgrd + + + repmgrd and cascading replication + + Cascading replication - where a standby can connect to an upstream node and not + the primary server itself - was introduced in PostgreSQL 9.2. &repmgr; and + repmgrd support cascading replication by keeping track of the relationship + between standby servers - each node record is stored with the node id of its + upstream ("parent") server (except of course the primary server). + + + In a failover situation where the primary node fails and a top-level standby + is promoted, a standby connected to another standby will not be affected + and continue working as normal (even if the upstream standby it's connected + to becomes the primary node). If however the node's direct upstream fails, + the "cascaded standby" will attempt to reconnect to that node's parent + (unless failover is set to manual in + repmgr.conf). + + + + + diff --git a/doc/repmgrd-witness-server.sgml b/doc/repmgrd-witness-server.sgml deleted file mode 100644 index 3bebca43..00000000 --- a/doc/repmgrd-witness-server.sgml +++ /dev/null @@ -1,31 +0,0 @@ - - - repmgrd - witness server - - - Using a witness server with repmgrd - - In a situation caused e.g. by a network interruption between two - data centres, it's important to avoid a "split-brain" situation where - both sides of the network assume they are the active segment and the - side without an active primary unilaterally promotes one of its standbys. - - - To prevent this situation happening, it's essential to ensure that one - network segment has a "voting majority", so other segments will know - they're in the minority and not attempt to promote a new primary. Where - an odd number of servers exists, this is not an issue. However, if each - network has an even number of nodes, it's necessary to provide some way - of ensuring a majority, which is where the witness server becomes useful. - - - This is not a fully-fledged standby node and is not integrated into - replication, but it effectively represents the "casting vote" when - deciding which network segment has a majority. A witness server can - be set up using . Note that it only - makes sense to create a witness server in conjunction with running - repmgrd; the witness server will require its own - repmgrd instance. - -