Is there a limit on logical volume size for FileVault?
According to Apple the maximum volume size and file size (using Mac OS X v10.5.3 or later) of a volume formatted with the HFS+ file system is close to 8 EB (exactly 2^63 - 2^31 = 9,223,372,034,707,292,160 B). This is also valid for encrypted volumes.



One fact cannot be concealed: the monstrous Logical Volume (the FileVault2 "envelope") is highly vulnerable to drive failure. The failure probability is comparable to a RAID0. Since FileVault doesn't use evenly spread chunks you may recover more data after a drive loss.

Here is a comparison for 10, 11 or 12 disks (8 TB):

Survival probability (for new 8 TB disks and being optimistic):

Nr of disks  1st year 2nd year 3rd year 4th year 5th year
         10       84%      37%      15%       8%       5%
         11       83%      33%      12%       7%       3%
         12       82%      30%      10%       5%       2%


If the disks are smaller than 8 TB (and the number of disks is higher) the survival probability is even worse.