[Bucardo-general] Swap replication latency
Alex Balashov
abalashov at evaristesys.com
Sun May 1 10:30:33 UTC 2011
Greetings,
I apologise if this is a poorly researched question; I looked through
the list archived extensively and wasn't able to find anything that
addressed my issue specifically.
I've got a simple swap replication setup between two servers,
consisting of a single sync of a single herd of a single database
consisting of about 50 tables and about as many sequences. Right now,
it's kind of an active-passive setup, it's just that the slave needs
to be writable in principle.
Compared to the setups that I'm sure some users of Bucardo are
running, I wouldn't say it's under a demanding load--maybe 5-6 writes
transactions/sec at most? Yet, I am seeing a lag of about 15-20
minutes until changes on the primary server show up on the secondary.
According to 'bucardo_ctl status <sync name>', I'm getting a "Last
good" run time between 10 and 12 minutes, and typically involving
~250/2349/10 Ins/Upd/Del ops. Ping is on. Obviously, my logs are
full of kicks and this message:
May 1 06:26:59 db Bucardo[28374]: CTL Could not add to q
sync=xxxxxxx_sync,source=xxxxxxx,target=xxxxxxxx_remote,count=1.
Sending manual notification
Is this normal (not the message, the 15-20 minute lag)? Is there
anything I can do to speed it up and make the replication process a
little more timely, if not necessarily real-time? I have tinkered
with a few of the options in the config table (i.e. 'bucardo_ctl show
all'), but without much luck. They aren't documented anywhere that I
can find, so I'm reluctant to mess with them too much.
I'm guessing that if there is a solution, it probably involves
squeezing more out of each sync through increased statement
length/value tuples, or by somehow further parallelising the sync
process when it runs.
Any light that can be shed would be deeply appreciated!
Thanks,
-- Alex
--
Alex Balashov - Principal
Evariste Systems LLC
260 Peachtree Street NW
Suite 2200
Atlanta, GA 30303
Tel: +1-678-954-0670
Fax: +1-404-961-1892
Web: http://www.evaristesys.com/
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