Thanks for your reply.<br><br>if the orig master is down say due to some hardware issue (for few hours/days say), we have to get the system on the slave up (we accept the loss of some N txn)<br><br>In this case, Is the following pseudcode correct. Assuming before crash of master, my master was node:1 and slave node:2<br>
On the slave (node 2), <br> a) i run failover command (failover (id=1, backup node = 2)<br> b) Run drop node command of node (1)<br> When the orig master is ready to be brought back in service can i re-use the node (1) for it?<br>
if so , is it enough to run just the following 2 commands on the original master<br> store node (id = 1, event node = 2);<br> store path (server=2, client=1, conninfo='connection info to node2')<br>
<br><div class="gmail_quote">On Tue, Feb 15, 2011 at 2:52 PM, Jan Wieck <span dir="ltr"><<a href="mailto:JanWieck@yahoo.com">JanWieck@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div class="im">On 2/15/2011 2:44 PM, Jan Wieck wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
This is NOT possible given the Slony-I design.<br>
<br>
Slony-I is an asynchronous replication system. That means that changes<br>
to the origin are replicated some time AFTER they have been committed.<br>
That means that if the origin goes down unexpectedly, you have no chance<br>
of knowing what changes did not propagate to the replica before it crashed.<br>
<br>
The only way to solve this situation is to actually do a hard FAILOVER,<br>
abandoning the old origin and rebuilding it from scratch.<br>
<br>
To illustrate, think about a simple foreign key constraint, <a href="http://t2.fk" target="_blank">t2.fk</a><br>
references <a href="http://t1.pk" target="_blank">t1.pk</a>. There currently are no rows in t2 referencing a<br>
certain <a href="http://t1.pk" target="_blank">t1.pk</a>, so node:1 will allow to DELETE it. Node:1 crashes before<br>
the DELETE can propagate to node:2. You failover to node:2 and since it<br>
still has the t1 row, it will happily allow you to INSERT references to<br>
it into t1. Now you bring back node:1 and ... how exactly do you get the<br>
</blockquote>
<br></div>
into t2, of course.<div><div></div><div class="h5"><br>
<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
two to agree what is right? Will you forcefully remove the rows, node:2<br>
inserted into t2 or will you recreate the t1 row in node:1 so that the<br>
INSERT's can propagate from node:2 to node:1?<br>
<br>
<br>
Jan<br>
<br>
</blockquote>
<br>
<br>
-- <br>
Anyone who trades liberty for security deserves neither<br>
liberty nor security. -- Benjamin Franklin<br>
</div></div></blockquote></div><br>