[Pgpool-general] pgpool-II and online recovery process

[Marcelo Martins]

Hi,

I have recently setup a VM environment to test out an online recovery  
process which works great. Basically I have the following.

pgpool-II 2.1 server:
1 - pgpool

3 postgresql 8.3.3 servers:
1 - db1  (backend_node0)
2 - db2  (backend_node1)
3 - db3  (backend_node2)

The 3rd PG server is kept in detached status so that I can use it for  
online recovery tests.
I have created the scripts for 1st/2nd stage and also the  
pg_remote_start script.
I can use pcp_recovery_node to bring a new node online (3rd PG server)  
or recover one of the existing ones without any issues.

Now, until today all my previous tests on performing online recovery  
involved calling pcp_recovery_node and during that time no clients  
were using the database servers through pgpool of course. There was no  
activity  going on on the database servers at all. So everything  
worked great, pgpool went through 1st and 2nd stage and then called  
the remote start and finished the recovery process. So server got  
online and sync'd.

Then, today I tried to do the same but right before calling  
pcp_recovery_node I started a pgbench process pointing to the pgpool  
server to create some activity on the database. I was under the  
impression that during 2nd stage pgpool would perhaps start to queue  
some of the transactions along with not allowing new clients to  
connect to it. Allowing the 2nd stage to occur and then bring the new  
node online. Once the online recovery was finished, pgpool would go  
through its queue and send those transactions to all nodes.
Is that not the case ? Cause basically it went through 1st stage and  
then pcp_recovery_node timed out.

Thanks,
Any input appreciated


Marcelo
Linux/Solaris System Administrator
http://www.zeroaccess.org