We’re gotten some small scale reports of customers who are finding that after running after some time with VAAI on their VMAX arrays are finding performance degradation. Usually this correlates with excessive back-end load and high read cache misses.
This is covered in primus article emc261696 (http://knowledgebase.emc.com).
Don’t jump to a conclusion – if you think you might be experiencing an issue – always open an SR. You can always call 1-800-SVC-4-EMC, and better yet – the e-support is getting really, really good (http://support.emc.com). Interestingly, online chat support is now covering a lot of support cases, and gets some of the best customer feedback.
A workaround (covered in the Primus article) is to disable VAAI on your hosts. You can disable VAAI across your vSphere clusters using this powershell script (thank you Nick). This requires rebooting the ESX host, but of course using vSphere’s maintenance mode, you can do this non-disruptively
Good news is there is already a fix. It is in a Enginuity epack that is available now. You get this via support.
Also good news is that the fix is in the Enginuity service release scheduled for 3/30.