Tag: Replication

Replication analysis with mycheckpoint

MySQL

I would like to show how mycehckpoint (see announcement) can be put to use for analyzing various replication metrics.

Lagging slaves

A slave has been monitored. Monitoring started at a time when it was way behind master (about two days lag), but it has since caught up. This can be easily verified by the following chart:

The above chart can be obtained by viewing the HTML report:

SELECT html FROM sv_report_html

Or by directly issuing the query:

mysql> SELECT seconds_behind_master FROM sv_report_chart_hour\G
*************************** 1. row ***************************
seconds_behind_master: http://chart.apis.google.com/chart?cht=lc&chs=400x200&chts=303030,12&chtt=Nov+5,+10:00++-++Nov+10,+08:00+(4+days,+22+hours)&chdl=seconds_behind_master&chdlp=b&chco=ff8c00&chd=s:976431zzzywutrpnliiifdbZYXVTRRRPNLJHEBAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA&chxt=x,y&chxr=1,0,169811&chxl=0:||Nov+6,+09:00|Nov+7,+09:00|Nov+8,+08:00|Nov+9,+08:00|&chxs=0,505050,10

This is all nice. But I’m also interested in the rate at which slave lag decreased. Many ignore this important metric: just how fast does your slave replicate?

Continue reading » “Replication analysis with mycheckpoint”

The importance of report_host & report_port

MySQL

The two server variables, report_host and report_port, are not commonly used. One of the reasons, I suspect, is that they do not appear in any of the standard .cnf files provided with a MySQL installation.

For a replication environment, I find these two variables to be very useful.

Where are these variables used?

Here’s a slightly modified exerpt from a MySQL master node I have, and which has two slaves: Continue reading » “The importance of report_host & report_port”

Parameters to use on mysqldump

MySQL

mysqldump is commonly used for making a MySQL database backup or for setting up a replication.

As in all mysql binaries, there are quite a few parameters to mysqldump. Some are just niceties but some flags are a must. Of course, choosing the parameters to use greatly depends on your requirements, database setup, network capacity etc.

Here is my usual setup for mysqldump. The parameters below apply for an InnoDB based schema (no MyISAM, Memory tables). Parameters can be specified on the command line, or under the [mysqld] scope in the MySQL configuration file.

mysqldump -u dump_user -p -h db_host --routines --master-data --single-transaction  --skip-add-locks --skip-lock-tables --default-character-set=utf8 --compress my_db

Let’s review these parameters and see their effect: Continue reading » “Parameters to use on mysqldump”