Hello everybody, 

 

We would like to know if there is a way to simplify the management of
SLONY in the case of a simple master-to-slave replication process.

 

Here is our structure: we have one master and 10 slaves, running
properly. We do not expect any of the slaves to become a master some
day. Everything is running well, except that there is a tremendous
activity on the master server due to the numerous SLONY processes. The
activity on each slave node is also far from being null even when there
is nothing to replicate.

 

Considering that the relationships between slave nodes were of no use in
our situation, we have decided, on a test configuration, to suppress all
the listen paths which seemed unuseful and to keep only the 20 obviously
useful listen paths. On the same way, we have kept only the 20 minimum
paths between the master and each slave. Under this new test
configuration, everything continued to run properly, the slave nodes had
there CPU activity being reduced. However, the master CPU activity
continued to be tremendous.

 

On a second step, we noticed first that the table sl_listen continued to
have 110 lines even if we had specified 20 listen paths. Consequently,
we cleaned each sl_listen table of each node of the SLONY cluster in
order to have a consistent situation. After a couple of hours, we have
noted that the CPU activity of the master node as well as the CPU
activity of the slave nodes have been considerably reduced, despite the
big number of SLONY processes remaining on each node (55 on the master
and 15 on each slave).

 

Our questions are: 

1- Is there a way to configure SLONY so that we can obtain the same good
results in terms of CPU use without cleaning manually the SL_LISTEN
tables?

2- Is there a way to minimize the number of SLONY processes on the
master and slave nodes?

3- Which parameters is it possible to change in order to minimize the
activity of the master and slaves?

4- Is it possible to configure the system so that the replication is
decided by the master node whenever necessary?

 

Thanks for your help.

 

Philippe Brinon & Philippe Daniels

 

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