We just did a 5.5 to 5.7 upgrade. Issues:
1. Default date precision is ON in 5.5 and OFF in 5.7. Our data compare process required us to write a utility to add precision ON in 5.7 translates (that didn’t already have precision set), and fix a few TCL files with the convert_date procedure (which uses the same precision internally).
2. The new RAIMA configuration wouldn’t let us continue to count recovery/error records more quickly with the keydump utility. We had to switch these to use hcidbdump.
We had a variety of other small issues that depend on specific implementation details, but those were the largest factors.
As a side note, we expected the RAIMA to be corruption free, but were still able to induce corruption in power-off setting, (not using HA). This was able to be triggered even in VMWare (which we use for our failover/etc.).
Hope this helps, feel free to PM me if you need any more discussion. Our implementation covers about 250+ threads.
Jerry