lol... How many large databases have you managed? Once evicted, MySQL
will be restarted by Pacemaker so all the caches will be cold. On a
128GB db server with an InnoDB buffer pool of >100 GB, warming the cache
takes hours and during that time the db is much slower. Since the slave
has been evicted because it was lagging, restarting it will not help at all.
Regards,
Yves
On 11-11-12 12:24 PM, Michael Marrotte wrote:
Why's evicted terrible? It optional and simply removes the slave node
from the cluster if it's lagging too far behind the master. The
collocation IP can float to another slave in the cluster or go
offline. I thought that's what you're looking for. I can post a
config if you're interested.
Sent from my iPhone
On Nov 12, 2011, at 11:51 AM, Yves Trudeau <y.trud...@videotron.ca
<mailto:y.trud...@videotron.ca>> wrote:
Hi,
Setting evict_outdated_slaves is terrible but then how do you
remove the read VIPs from slaves that are outdated. If there is a
way to do it, tell me :) I am always open to do things in a simpler
way. This solution works without evicting outdated slaves. The
current mysql RA does behave correctly HA wise but it is less than
optimal database wise. I mean in small installations it is probably
ok, but at Percona, I hit many high end installations where the
current behavior is not adequate. I consider myself more as a
database specialist than an HA one so I may be more sensitive to
these problems.
Regards,
Yves
On 11-11-12 09:19 AM, Michael Marrotte wrote:
Are you using evict_outdated_slaves?
<parameter name="evict_outdated_slaves" unique="0" required="0">
<longdesc lang="en">
If set to true, any slave which is more than max_slave_lag seconds
behind the master has its MySQL instance shut down. If this parameter
is set to false in a primitive or clone resource, it is simply
ignored. If set to false in a master/slave resource, then exceeding
the maximum slave lag will merely push down the master preference so
the lagging slave is never promoted to the new master.
</longdesc>
<shortdesc lang="en">Determines whether to shut down badly lagging
slaves</shortdesc>
<content type="boolean"
default="${OCF_RESKEY_evict_outdated_slaves_default}" />
</parameter>
On Fri, Nov 11, 2011 at 9:57 PM, Yves Trudeau
<y.trud...@videotron.ca <mailto:y.trud...@videotron.ca>> wrote:
Because that's not enough, if a slave lags behind too much, I
want to remove the vip but not stop the slave.
On 11-11-11 06:12 PM, Michael Marrotte wrote:
Why don't you simply colocate VIP's with the master/slave roles?
On Fri, Nov 11, 2011 at 5:18 PM, Yves Trudeau
<y.trud...@videotron.ca <mailto:y.trud...@videotron.ca>> wrote:
Hi,
I created a fork of the resource-agents and modified the
mysql RA to supports VIP. The support for read/write VIPs
is something that currently limits the use of pacemaker to
manage mysql replication. I ran some basic tests on the
modified agent and it seems behaving sanely so far but more
tests will be needed (next week). I also modified a few
things in the RA that were not optimal in my view. Here's
the URL for my fork:
git://github.com/y-trudeau/resource-agents.git
<http://github.com/y-trudeau/resource-agents.git>
https://y-trud...@github.com/y-trudeau/resource-agents.git
In order to use it, you need to adapt the pacemaker
configuration, here's the one I am using:
http://pastebin.com/QPJPWDhx
Next, apart from running more tests, I want to do the
following:
- review user privileges used, need to lower the ones of
replication_user
- add support for MHA
(http://code.google.com/p/mysql-master-ha/)
- run a beautifier for more uniformity in style
Reviews and comments are of course welcome.
Regards,
Yves
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