Issues after memcached version upgrade

[joelbatistaferreira]

Hi there.

I'm using mcrouter v0.40.0 to populate AWS Memcached clusters.
I was using AWS Memcached cluster version 1.5.16 and default.memcached1.5 parameter group.

I've deployed a new cluster in version 1.6.17 (default.memcached1.6 parameter group) and pointed mcrouter there using migrationroute policy.
After a while the number of current items increased by a factor of 20x. Evictions started to increase.
No changes to the application were done.

I've deployed a new cluster on version 1.5.16 and evictions dropped to 0.
The number of current items came back to normal.

Has anyone faced something like this before?
Is there any (in)compatibility with mcrouter / memcached versions?
Is there any specific parameter I should add to parameter group?

Thanks in advance