I know the purpose of "EFI", "Boot OS X", and "Recovery HD" partitions. But why are there three different "Macintosh HD" partitions? And should there be two EFI partitions? ![enter image description here][1] [1]: https://i.sstatic.net/0Mpyb.png UPDATE Here is what `disktutil list` reports /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *121.3 GB disk0 1: EFI EFI 209.7 MB disk0s1 2: Apple_CoreStorage 121.0 GB disk0s2 3: Apple_Boot Boot OS X 134.2 MB disk0s3 /dev/disk1 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *3.0 TB disk1 1: EFI EFI 209.7 MB disk1s1 2: Apple_CoreStorage 2.7 TB disk1s2 3: Apple_Boot Recovery HD 650.1 MB disk1s3 4: Apple_HFS Data 326.8 GB disk1s4 /dev/disk2 #: TYPE NAME SIZE IDENTIFIER 0: Apple_HFS Macintosh HD *2.8 TB disk2 Logical Volume on disk0s2, disk1s2 03BC8817-F05E-4FC3-9A5C-50130CDAB3AB Unencrypted Fusion Drive