I have a few questions in regards to upgrading the RDS instance.
Upgrades to the database engine level require downtime. Even if your RDS DB instance uses a Multi-AZ deployment, both the primary and standby DB instances are upgraded at the same time. This causes downtime until the upgrade is complete, and the duration of the downtime varies based on the size of your DB instance.
The instance upgrade on the slave usually takes around 10 to 20 minutes, but there is no downtime in this setup.
Updating the DB instance class The standby instance is first modified, causing a failover. After the failover, the new standby is modified. The downtime required includes the duration of a failover completion, typically 60-120 seconds, and completion of the DB engine's crash recovery.
MySQL major version upgrades typically complete in about 10 minutes. Some upgrades might take longer because of the DB instance class size or because the instance doesn't follow certain operational guidelines in Best practices for Amazon RDS.
I don't think this is an on-topic question for StackOverflow at all, but some information anyway:
It's significant and depends on the size of the database. I've had it take an hour or more some times. I've also had creating snapshots, restoring from snapshots, and multi-az creation take around two hours before.
It depends on how you have things configured now. If you have Multi-AZ already enabled, then an instance upgrade will actually occur on the slave, then a failover will occur, then the new slave is updated. This results in about 1 or 2 minutes of actual downtime. The instance upgrade on the slave usually takes around 10 to 20 minutes, but there is no downtime in this setup. Note that when it does the failover, Amazon does a DNS swap internally so that your RDS endpoint points to the right machine, so you may have to restart your web processes that point to the DB so that they reconnect to the DB and pull in the new IP from a new DNS lookup.
db.t1.micro > db.m1.small : 8m30s
Engine: mysql Storage: 6GiB Backups: Yes Multi A-Z: No
The size/type of the database do appear to affect the downtime significantly.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With