Hello, Thank you to head me the previous discussion. I'll consider them from now.
> > I want the standby to start to serve as soon as possible even by > > a few seconds on failover in a HA cluster. > > Please implement a prototype and measure how many seconds we > are discussing. I'm sorry to have omitted measurement data. (But it might be shown in previous discussion.) Our previous measurement of failover of PostgreSQL 9.1 + Pacemaker on some workload showed that shutdown snapshot takes 8 seconds out of 42 seconds of total failover time (about 20%). OS : RHEL6.1-64 DBMS : PostgeSQL 9.1.1 HA : pacemaker-1.0.11-1.2.2 x64 Repl : sync Workload : master : pgbench / scale factor = 100 (aprx. 1.5GB) standby: none (warm-standby) shared_buffers = 2.5GB wal_buffers = 4MB checkpoint_segments = 300 checkpoint_timeout = 15min checpoint_completion_target = 0.7 archive_mode = on WAL segment comsumption was about 310 segments / 15 mins under the condition above. > This proposal is for a performance enhancement. We normally require > some proof that the enhancement is real and that it doesn't have a > poor effect on people not using it. Please make measurements. On the benchmark above, extra load by more frequent (but the same to the its master) checkpoint is not a problem. On the other hand, failover time is expected to be shortened to 34 seconds from 42 seconds by omitting the shutdown checkpoint. (But I have not measured that..) > Discussion on a patch submitted to me to the Januray 2012 CommitFest > to reduce failover time. Thank you and I'm sorry for missing it. I've found that discussions and read them from now. regards, -- Kyotaro Horiguchi NTT Open Source Software Center == My e-mail address has been changed since Apr. 1, 2012. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers