I have read many posts about replication from RDS to external and vice versa. But my need is actually a bit different. I need to set replication between two RDS instances.

Of course I know about Multi AZ, but the need to replicate is due to this:

I have already allocated 1TB for my RDS instance, but my DB is around 300GB only. The additional disk is costing very much. RDS doesn't provide an option to downgrade in terms of disk space. So my only option is either do a manual mysql dump and import to new RDS instance, because my DB size is about 300GB doing a dump and importing is not a good idea is it?

Only option I am left with is, setup master-slave, master will be current RDS and slave will be new RDS with maybe a 350GB disk. Once slave is in Sync with master I will stop master and start using the slave. Here again I am stuck with one issue, I will have to import data from master to slave to initialize replication isn't it? And with 300GB of data how will I do it?

Also all the docs I have read is about replication between external MySQL and RDS, not between RDS instances. Has anybody ever had the need to do the same? How did it go? Any detailed steps to follow?

  • Keep in mind that if you need to ALTER a table, or do other maintenance, you may need enough spare disk space for a complete copy of the table. – Rick James Oct 18 '16 at 18:09
  • Does RDS have a convenient way (sort of dump+load) to add a Slave? The dump will take hours. And you need disk space for the dump. – Rick James Oct 18 '16 at 18:10
  • You can try to migrate on a new instance with lower storage size using AWS DMS: console.aws.amazon.com/dms/home?region=us-east-1# . I spend a few days to test it and I like it, but I have not used it on production yet – Alexey Oct 28 '16 at 20:56

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