Re: [Postgres-xc-general] pgbench suggestion

[Tatsuo I. <is...@po...>]

> On Fri, Nov 16, 2012 at 2:12 PM, Tatsuo Ishii <is...@po...> wrote:
> 
>> >> >> We have up to 8 servers, where each server has data
>> >> >> node/coorrdinator/GTM proxy. We have GTM on a seprate server. Then we
>> >> >> execute multiple pgbench -k -S against the servers(each pgbench
>> >> >> connect to different server).
>> >> >>
>> >> > OK, this should not happen...
>> >> > How many max connections are you using per Coordinator
>> >>
>> >> 100.
>> >>
>> >> > and how many
>> >> > Coordinators do you have?
>> >>
>> >> Up to 4.
>> >> The number of coordinators are same as data nodes. So when we test 4
>> >> data nodes(suppose they are d1 to d4), we are doing something like
>> >> this:
>> >>
>> >> on host c1: pgbench -c 100 -S -h d1
>> >> on host c2: pgbench -c 100 -S -h d2
>> >> on host c3: pgbench -c 100 -S -h d3
>> >> on host c4: pgbench -c 100 -S -h d4
>> >>
>> > That looks OK. I was wondering if the maximum active transactions
>> possible
>> > on GTM (1024) was reached, leading to your error.
>> > The warning "Cannot connect to GTM..." "Xid is invalid." only happens
>> when
>> > a node tries to get a connection from GTM but it cannot, making me think
>> > that GTM is not online or you have some firewall/network problems between
>> > the node and GTM.
>>
>> The error seems not depending on number of node. We did the similar
>> way as 4 nodes above against 8 nodes configuration. Sometimes we saw
>> the error, sometimes not. Also we saw the error when the number of
>> nodes less than 4, for example 2 or 1.
>>
> I believe here in a configuration mistake. I work here with clusters up to
> 10 servers and do not see that if connection to GTM is made correctly even
> with a huge load.
> Please double-check gtm_host and gtm_port in each node's postgresql.conf,
> then check what is the port open on GTM.

Each server has data node, coordinator, and GTM proxy. Every
postgresql.conf has gtm_host = 'localhost' and gtm_port = 6666.  We
double checked all postgresql.conf has same value and also GTM proxy
is up and running.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp