extremely slow MyISAM slave updates

Question

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?

Answer 1

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.