Re: n-way multi master and mirror mode

[Quanah Gibson-Mount <quanah@symas.com>]

--On Sunday, December 04, 2016 3:42 PM -0500 Brendan Kearney 
<bpk678@gmail.com> wrote:

> my line of thinking was that if mirror mode was not appropriate for multi
> master replication, then i would remove the setting and eliminate the
> item from my list of potential contributing factors.  if mirror mode is
> not needed, there are potential efforts and cpu cycles being spent on
> doing work that is unnecessary or even detrimental to the performance of
> slapd.  i am looking make sure mirror mode is safe to remove from my
> configs, so i can test the theory.

Hi Brendan,

Again, Mirror Mode is a concept, not a setting.  The setting you refer to, 
is, as I previously noted, misnamed.  Either your servers are configured to 
do multimaster replication, or they aren't.

The only time /any/ type of replication, whether it is multimaster or 
provider/consumer, is really going to have an impact is if you have a 
significant amount of sustained writes happening.  So far, it sounds like 
your traffic is almost entirely reads.


> ReceivedAt                    SysLogtag        Message
> 2016-11-15 20:35:05    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:05    slapd[1514]:     connection_input: conn=6836
> deferring operation: pending operations
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing
> 2016-11-15 20:35:11    slapd[1514]:     connection_input: conn=6836
> deferring operation: too many executing

Yes, you'd need stats logging, and it appears that all of those were only 
deferred for fractions of a second, which is why you see multiple messages 
per second.  So there's not really any indication here of a problem that I 
can see.


> i am running OpenLDAP: slapd 2.4.44 on fedora 24 using lmdb.


> listener threads are the default of 1, and the value is not set.

I was asking about "threads/olcThreads", not the listener threads value. 
That default is 16.


Regards,
Quanah

--

Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>