Questions regarding disk format I'm doing a fresh install of Yosemite on my mac, but stopped at format step: I noticed various options:


plain format
encrypted
case sensitive


So, I'd like to know:


Is it possible to install Yosemite on an encrypted partition? If
   yes, there are downsides?
Is this equivalent to installing on unencrypted disk and perform
encryption from OS with FileVault? If not, may you explain the
difference?
I'm tempted to choose Case Sensitive to have a more "true Unix"
environment. May this cause issues with OS and apps?


I googled, but those answers are rather difficult to find.

Thanks a lot.
You can install Yosemite on an encrypted partition. To use encryption, you also have to use core storage. If you do not use encryption, then the use of core storage is optional. If you encrypt after installing without core storage, then a conversion to core storage will take place. Fusion drives require the use of core storage. Yosemite can only be installed on a partition that is case insensitive. Personally, I have avoided using core storage. I do not see any advantages to using it unless you have to.