Comments on: Three ways to know when a MySQL slave is about to start lagging http://www.mysqlperformanceblog.com/2008/10/08/three-ways-to-know-when-a-mysql-slave-is-about-to-start-lagging/ Percona's MySQL & InnoDB performance and scalability blog Sat, 11 Feb 2012 16:45:54 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Baron Schwartz http://www.mysqlperformanceblog.com/2008/10/08/three-ways-to-know-when-a-mysql-slave-is-about-to-start-lagging/comment-page-1/#comment-361315 Baron Schwartz Sat, 11 Oct 2008 17:37:43 +0000 http://www.mysqlperformanceblog.com/?p=511#comment-361315 Sean, describe what you'd like them to graph. Oh, and if you want commit rights to the SVN repository, just say yes :) Sean, describe what you’d like them to graph. Oh, and if you want commit rights to the SVN repository, just say yes :)

]]> By: peter http://www.mysqlperformanceblog.com/2008/10/08/three-ways-to-know-when-a-mysql-slave-is-about-to-start-lagging/comment-page-1/#comment-361127 peter Fri, 10 Oct 2008 19:41:32 +0000 http://www.mysqlperformanceblog.com/?p=511#comment-361127 Baron, I would note "Bumpy" Lag graphs can also start happening in case you have some long executing queries being passed to the slave which is bad thing on itself. I would recommend avoiding queries longer than 1/3rd of accepted lag in the replication. Ie if you want to be within 60sec you should ensure no queries going through replication take more than 20sec to execute. Speaking about slave load I'd like to see slave to have at least 5x capacity when it is idle and at least 3x when it is operating during normal load this means you can take some spikes without lagging, though it is very application dependent. Considering how much it takes to do roll forward recovery from backup is another important thing to keep in mind. Baron,

I would note “Bumpy” Lag graphs can also start happening in case you have some long executing queries being passed to the slave which is bad thing on itself.

I would recommend avoiding queries longer than 1/3rd of accepted lag in the replication. Ie if you want to be within 60sec you should ensure no queries going through replication take more than 20sec to execute.

Speaking about slave load I’d like to see slave to have at least 5x capacity when it is idle and at least 3x when it is operating during normal load this means you can take some spikes without lagging, though it is very application dependent.

Considering how much it takes to do roll forward recovery from backup is another important thing to keep in mind.

]]> By: Sean http://www.mysqlperformanceblog.com/2008/10/08/three-ways-to-know-when-a-mysql-slave-is-about-to-start-lagging/comment-page-1/#comment-361039 Sean Fri, 10 Oct 2008 07:18:22 +0000 http://www.mysqlperformanceblog.com/?p=511#comment-361039 Baron, any future plans to create cacti graphs to log the *_statistics tables and/or include the #mysql_system# user in the replication templates? :) Baron, any future plans to create cacti graphs to log the *_statistics tables and/or include the #mysql_system# user in the replication templates? :)

]]> By: Baron Schwartz http://www.mysqlperformanceblog.com/2008/10/08/three-ways-to-know-when-a-mysql-slave-is-about-to-start-lagging/comment-page-1/#comment-360918 Baron Schwartz Thu, 09 Oct 2008 13:54:35 +0000 http://www.mysqlperformanceblog.com/?p=511#comment-360918 frederic, you have to take some load off the server. We have a whole section in our book about how to help slaves keep up. It's in the replication chapter. http://www.amazon.com/gp/product/0596101716?tag=perinc-20 frederic, you have to take some load off the server. We have a whole section in our book about how to help slaves keep up. It’s in the replication chapter. http://www.amazon.com/gp/product/0596101716?tag=perinc-20

]]> By: Patrick Domack http://www.mysqlperformanceblog.com/2008/10/08/three-ways-to-know-when-a-mysql-slave-is-about-to-start-lagging/comment-page-1/#comment-360916 Patrick Domack Thu, 09 Oct 2008 13:48:01 +0000 http://www.mysqlperformanceblog.com/?p=511#comment-360916 I have been using the mk-heartbeat type method for a few years now (using my own version). I found this excentual to actually being able to tell many issues with a slave itself. I have also wrapped the main critical mysql connected around checking the lag, and if it's excessive, to switch to a different slave. It has worked well. I have been using the mk-heartbeat type method for a few years now (using my own version). I found this excentual to actually being able to tell many issues with a slave itself. I have also wrapped the main critical mysql connected around checking the lag, and if it’s excessive, to switch to a different slave. It has worked well.

]]> By: frederic sidler http://www.mysqlperformanceblog.com/2008/10/08/three-ways-to-know-when-a-mysql-slave-is-about-to-start-lagging/comment-page-1/#comment-360821 frederic sidler Thu, 09 Oct 2008 08:31:06 +0000 http://www.mysqlperformanceblog.com/?p=511#comment-360821 Assuming that you have no network problem between your nodes. What would you do next. I mean if your slave begins to lag behind your master Assuming that you have no network problem between your nodes. What would you do next. I mean if your slave begins to lag behind your master

]]> By: Baron Schwartz http://www.mysqlperformanceblog.com/2008/10/08/three-ways-to-know-when-a-mysql-slave-is-about-to-start-lagging/comment-page-1/#comment-360700 Baron Schwartz Thu, 09 Oct 2008 03:20:24 +0000 http://www.mysqlperformanceblog.com/?p=511#comment-360700 Don't load your slaves so much that they fall behind. Plan for the slaves to have a hard time keeping up with the master, even with the same or better hardware. Plan for slave lag and make your application cope with it. Don’t load your slaves so much that they fall behind.

Plan for the slaves to have a hard time keeping up with the master, even with the same or better hardware.

Plan for slave lag and make your application cope with it.

]]> By: Rob Wultsch http://www.mysqlperformanceblog.com/2008/10/08/three-ways-to-know-when-a-mysql-slave-is-about-to-start-lagging/comment-page-1/#comment-360675 Rob Wultsch Thu, 09 Oct 2008 02:00:23 +0000 http://www.mysqlperformanceblog.com/?p=511#comment-360675 Any general comments about max advised load on slaves? Any general comments about max advised load on slaves?

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