Ok, so AK8.1 has some cool new features. One of which is the ability to have block or record sizes on your shares larger than the current 128K. You can now have 256K, 512K, and 1M. This is important for some great performance boosts on different types of workloads.
This feature is a deferred update in AK8.1. In other words, just upgrading to AK8.1 does not turn on this feature. Also, after you apply the deferred update, you will NOT be able to roll-back to a previous version. So test and check before you apply.
Here is my screen after the upgrade. Note the new "Deferred Update" section that appears.
If you click the "More info" button, you will see the following help file:
So, before I apply the deferred update, if I go into a share, I will see the large block sizes in the pull-down but note that they are greyed out.
After I apply the update, which does NOT require a reboot and is very quick, the same menu now has black entries that I can choose.