I have a Supermicro server running ESXi5.1 that recently started having the same issues... my HP P410 SAS controller died and I replaced it with an Adaptec 3405, recreated the RAID array and reloaded all my VMs, within hours I was having errors such as 'WARNING: ScsiDeviceIO: 6693: IEC page to device "mpx.vmhba2:C0:T0:L0" has bad pagecode: 0x0' and i would have VMs lock up intermittently, server performance monitoring would so IO to the disk drop to zero, then if I left it alone it would come back after a few minutes. Attempting to shut down VMs, log in, etc would result in a host hang most the time.
I checked the HCL and my Adaptec controller is listed and the firmware and driver are correct: VMware Compatibility Guide: I/O Device Search
Any ideas? I'd hate to have to replace my RAID controller again so soon...
EDIT: I wanted to post an update in case anyone else finds this useful. Adaptec is not supporting some of the older cards on ESXi 5.1, per their site:
http://ask.adaptec.com/app/answers/detail/a_id/17086/~/adaptec-raid-controllers-and-vmware-support
Seems like only the series 7 cards are supported as of 5.1