12.02.2013 02:35, Takatoshi MATSUO пишет:
Hi
2013/2/9 Andrew <ni...@seti.kr.ua>:
Hi all.
For what reason is implemented PGSQL.lock in RA, and what pbs may happen if
it'll be removed from RA code?
It may cause data inconsistency.
If the file exists in a node, you need to copy data from new master.
I noticed that during master migration lock still remains and postgresql
isn't started on old master; demote also will fail with lock file. Also,
if cluster fails (for ex., power failure occurs), old master will not
start, and slave after startup will be promoted to master - it's OK when
both nodes are crashed simultaneously, and it's really bad when old
slave was crashed earlier. If postgres crashed/killed by OOM/etc - it
also will not be restarted...
Maybe it'll be better to watch log files on slave that tries to sync
with master/to check slave timeline, and if slave can't sync with error
that timeline differs - to fail it with error (or even to sync with
master with pg_basebackup - it supports connection to remote server and
works quick:
http://sharingtechknowledge.blogspot.com/2011/12/postgresql-pgbasebackup-forget-about.html
- example)?
Also, 2nd question: how I can prevent pgsql RA from promoting master before
both nodes will brings up OR before timeout is reached (for ex., if 2nd node
is dead)?
You can use xlog_check_count parameter set up with a large number.
RA retries comparing data with specified number of times in Slave.
Thanks; I'll try this.
Or you can use "target-role" such as below too.
----
ms msPostgresql pgsql \
meta master-max="1" master-node-max="1" clone-max="2"
clone-node-max="1" notify="true" target-role="Slave"
---
In that case, how can I choose on what node I should promote resource to
master (which has fresher WAL position) - I should do this manually, or
I can just run promote?
I think that clone of Delay RA for both nodes (to avoid switching
delay on node with Delay resource failure) will do this - but I can't find
how I should write such rule, it seems like rules in Pacemaker are too
simple (or too bad described). I expect something like this (in <> braces I
included rules that I don't know how to write):
location pgsql_master_location ms_Postgresql \
rule $role="master" -inf: <Delay RA is not running> and <ms_Postgresql
count eq 1>
Is this possible?
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_______________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
http://oss.clusterlabs.org/mailman/listinfo/pacemaker
Project Home: http://www.clusterlabs.org
Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
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