A few colleagues of mine recently worked with a customer deploying VMware Virtual SAN (VSAN) with Cisco UCS hosts using the LSI MegaRAID 9271CV-81 I/O Controller and documented the configuration choices below. Note, in general the VSAN guidance has been to disable all controller cache so these choices follow this theme. Also note that we are not LSI experts and would welcome feedback from others on their experience with other settings.
Change the default settings in the screenshot below to the following:
- Access = RW
- I/O = Direct
- Read = Disable
- Disk Cache = Disabled
- Disable BGI = No
- Default Write = Write Through
* All settings can be changed on the fly or using storcli for VMware:
* User guide
Other versions of the MegaRAID controller might have a screen that looks something like the one below:
Thanks to my colleagues Justin Beck and Jason Burroughs for documenting and sharing their experience.
Live Virtually 
why not raid 10 for extra protection?
VSAN is Software Defined Storage so it deals with protection using software rather than hardware. In other words, rather than putting two copies of the same data block on the same host (hardware RAID 1), VSAN puts each copy on different hosts (software defined distributed RAID 1)
whether the VSAN should use a RAID controller for testing?
This is great and very helpful, the only thing, is this config for the ssd connect to the LSI or for the spinning disks? or both? wondering if the read and write policy should be different for the 2 different types
This is the recommended config for both SSD and HDD. VSAN leverages the SSD for both read and write caching so best not to be also doing it in hardware. Thus, IO Controller and disk caching should be disabled.