i have two questions. (1) innodb? (2) why delete slave logs when you can restart the slave with --skip-slave and then use CHANGE MASTER TO?
tom On 12/4/09 6:34 AM, "Robinson, Eric" <eric.robin...@psmnv.com> wrote: > > Let's face it, sometimes the master and slave get out of sync, even when > 'show slave status' and 'show master status' indicate that all is well. > And sometimes it is not feasible to wait until after production hours to > resync them. We've been working on a method to do an emergency > hot-resync during production hours with little or no user downtime. What > do you guys think of this approach? It's only for Linux, though... > > 1. Shut down the slave and remove its replication logs (master.info and > *relay* files). > > 2. Do an initial rsync of the master to the slave. Using rsync's > bit-differential algorithm, this quickly copies most of the changed data > and can be safely be done against a live database. This initial rsync is > done before the next step to minimize the time during which the tables > will be read-locked. > > 3. Do a 'flush tables with read lock;reset master' on the master server. > At this point, user apps may freeze briefly during inserts or updates. > > 4. Do a second rsync, which goes very fast because very little data has > changed between steps 2 and 3. > > 5. Unlock the master tables. > > 6. Restart the slave. > > When you're done, you have a 100% binary duplicate of the master > database on the slave, with no worries that some queries got missed > somewhere. The master was never stopped and users were not severely > impacted. (Mileage may vary, of course.) > > We've tried this a few times and it has seemed to work well in most > cases. We had once case where the slave SQL thread did not want to > restart afterwards and we had to do the whole thing again, only we > stopped the master the second time. Not yet sure what that was all > about, but I think it may have been a race issue of some kind. We're > still exploring it. > > Anyway, comments would be appreciated. > > -- > Eric Robinson -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
