On Sun, 21 Mar 2010, Philippe Clérié wrote:
So I cannot just restart Node1, restart Slony on both nodes and do MOVE SET?
If I get the docs correctly, FAILOVER assumes the original node is not
coming back up. Actually it's up but I haven't reconnected it to the
internet pending a solution to the replication problem.
Since you are restoring node 1 to a backup from three weeks ago you can't
issue a move set. Slony won't have a complete record of the changes made to
your database between your last backup (three weeks ago) and the time your
server went down.
You want to issue a failover command, then re-add node 1 to your cluster as
a new node and have slony copy the data from node 2 to node 1 as part of
the set subscription.
Once node 1 is caught up you could use 'move set' to move the set from node
2 back to node 1 but you first have to use failover to make node 2 the
provider and re add+subscribe node 1.
Steve
--
Philippe
------
The trouble with common sense is that it is so uncommon.
<Anonymous>
On Sunday 21 March 2010 11:15:00 Guillaume Lelarge wrote:
Le 21/03/2010 15:37, Philippe Clérié a écrit :
I am trying to recover from a catastrophe and I am about to do
something new and I need some reassurance that it's the correct
procedure.
I have a Slony replication set with two nodes in a master/slave
configuration, Postgresql 8.1, Slony 1.2.1 on Debian Etch. Node1
(master) was taken out of commission (think a rm -rf * type error).
I've recovered from a previous backup that's about 3 weeks out of date,
but Node2 is up to date. I want Node2 to update Node1 and then I want
to go back to normal.
If I understood correctly, according to the docs, the MOVE SET command
is the appropriate saviour. So I want to execute the following script
on Node1:
cluster name = mycluster;
node 1 admin conninfo='host=xxxxxxx';
node 2 admin conninfo='host=yyyyyyy';
execute script (
lock set (id = 1, origin = 1);
wait for event (origin = 1, confirmed = 2);
move set (id = 1, old origin = 1, new origin = 2);
wait for event (origin = 1, confirmed = 2);
);
Taken right out of the book.
Nope, if Node 1 is unavailable, you should do a failover (and not a
switchover). See failover slonik command
(http://www.slony.info/documentation/stmtfailover.html).
I'll a reasonable amount of time (an hour should suffice), then again
on Node1 I would execute the same script but reversing the origins:
cluster name = mycluster;
node 1 admin conninfo='host=xxxxxxx';
node 2 admin conninfo='host=yyyyyyy';
execute script (
lock set (id = 1, origin = 2);
wait for event (origin = 2, confirmed = 1);
move set (id = 1, old origin = 2, new origin = 1);
wait for event (origin = 2, confirmed = 1);
);
This one is good. But you need to wait until they are synchronized.
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