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I have 2 slaves and one is working as expected. The other slave is extermely slow while executing the "update" statements. The insert and deletes are fast. I used "check table tbl_name" to see if any MyISAM table was corrupt. Both the slaves are MyISAM only.

I am using (AWS ec2 instance) ext3 for the fast slave and xfs for the the other. Is that the reason why the updates are taking time?

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You are at the mercy of what AWS thinks is a good config for your part of a computer. Post more details; maybe there is something that can be fixed. – Rick James May 29 '12 at 21:24
up vote 1 down vote accepted

You can compare both slaves performance using Percona utilities mentioned below:

  • pt-heartbeat measures replication lag on a MySQL server. You can use it to update a master or monitor a replica. If possible, MySQL connection options are read from your .my.cnf file.
  • pt-table-checksum performs an online replication consistency check by executing checksum queries on the master, which produces different results on replicas that are inconsistent with the master.
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