I have 14 Dell R730 servers running ESXi 5.5 from mirrored internal SD cards (no hard drives in any server). It works well, but the downside is that I have no host log file history across server restarts. I could purchase drives to install for this, but that would be pretty expensive, so I'd like to try using low profile USB sticks (https://www.amazon.com/gp/product/B017DH3O5A) instead. Again, this would be for local host log file operations only, not VM datastore use, and would be temporary pending installation of a central logging solution early next year