FileVault 2必須有Recovery HD分區，因為它依賴於它作為系統初啟動。如果今後什麼時候或者誤操作刪除了Recovery HD分區，那麼你的機器就無法啟動鳥。 是否使用蘋果的辦法重新獲得一個Recovery HD就可以了呢？原理上說不行，因為還記得當初加密的時候的密鑰嗎？它也丟了，丟了就無法解密了。所以呢，我們需要另辟途徑來恢復它。
一般步驟：
基於一個FileVault 2是基於CoreStorage邏輯卷管理技術的事實，我們可以從CoreStorage入手。
先看看一個被加密過的磁盤回變成什麼樣子，注意其中的Unlocked行，後面會提到：
[python]
$ diskutil coreStorage list
CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group 26B67367-CF79-4D1E-884C-BB96FDD79D19
=========================================================
Name: FileVault
Sequence: 1
Free Space: 0 B (0 B)
|
+-< Physical Volume A446F211-3BCB-47F4-8EB2-7174AF4CD408
| ----------------------------------------------------
| Index: 0
| Disk: disk4s2
| Status: Online
| Size: 9896046592 B (9.9 GB)
|
+-> Logical Volume Family 8D077574-ADC1-4979-9F1E-FF901FC20D86
----------------------------------------------------------
Sequence: 8
Encryption Status: Unlocked
Encryption Type: AES-XTS
Encryption Context: Present
Conversion Status: Complete
Has Encrypted Extents: Yes
Conversion Direction: -none-
|
+-> Logical Volume BD95F022-812D-366A-909C-286E5443D88E
---------------------------------------------------
Disk: disk5
Status: Online
Sequence: 4
Size (Total): 125505781760 B (125.5 GB)
Size (Converted): 125505781760 B (125.5 GB)
Revertible: Yes (unlock and decryption required)
LV Name: FileVault
Volume Name: FileVault
Content Hint: Apple_HFS
它原來看上去是這個樣子的：
[python]
diskutil info disk0s2
Device Identifier: disk0s2
Device Node: /dev/disk0s2
Part of Whole: disk0
Device / Media Name: Macintosh HD
Volume Name: Macintosh HD
Escaped with Unicode: Macintosh%FF%FE%20%00HD
Mounted: Yes
Mount Point: /
Escaped with Unicode: /
File System Personality: Journaled HFS+
Type (Bundle): hfs
Name (User Visible): Mac OS Extended (Journaled)
Journal: Journal size 16384 KB at offset 0x1ab63000
Owners: Enabled
Partition Type: Apple_HFS
OS Can Be Installed: Yes
Media Type: Generic
Protocol: SATA
SMART Status: Verified
Volume UUID: BD95F022-812D-366A-909C-286E5443D88E
Total Size: 125.5 GB (125505781760 Bytes) (exactly 245128480 512-Byte-Blocks)
Volume Free Space: 62.2 GB (62152081408 Bytes) (exactly 121390784 512-Byte-Blocks)
Device Block Size: 512 Bytes
Read-Only Media: No
Read-Only Volume: No
Ejectable: No
Whole: No
Internal: Yes
Solid State: No
其它的都不重要，重要的是他的Volume UUID，也就是 "BD95F022-812D-366A-909C-286E5443D88E"，
另外加密時的密鑰也不要忘了，密鑰這個樣子：
現在使用下面的命令來解密吧：
www.dnzg.cn
[python]
$ diskutil coreStorage revert <span style="font-size:18px; ">BD95F022-812D-366A-909C-286E5443D88E</span> -passphrase 2NTO-LQGA-RMXG-LFQO-B8NR-XTCT
解密之後的時這樣子的：
[python]
$ diskutil coreStorage list
