My Book Essential 2T USB3 bootable or not on Mac OS X 10.9


i buy this My Book 2T some months ago and i only install OS  X 10.9.2 and don’t use it until one week ago.

Booting is impossible so :

• i re-format and re-intall (with Disk Maker X) and it boot correctly (with 10.9.3) at the end of the install but after shutdown it won’t recognize the boot disk

• i re-do it once with the My Book and an other external disk (Seagate) in another enclosure (verbatim with usb3 too) and it boot fine from the Seagate but not from the WD so the problem is not how i do the installation but with what

• some time when i plug the usb 3  a noise come from disk at start

• i try reset pram with +alt+p+r five time

• i try reset SMC

• i try +s and fsck -yf (nothing anormal was found)

• i repair permissions and check the disk with diskutility

But i have again and again either the folder with question mark or the no entry symbol.

noway.png or   folder_question_mark.png

If someone has an idea …



Try running a Disk Utility test.

How to test a drive for defects or problems on a Mac 

Sorry Ichigo, i have forgotten to write it but i did “repair permissions and verify disc” with disc utility.

And DriveDx print smart is ok



Please note only specific WD Drives are bootable within an Apple Mac OS system. Please visit the following link for additional information:

Thanks JStaff

My disk is this My Book ( model 2T so it seems it is bootable.

• i have done the firmware update but nothing change.

• i have reformat the disk in Fat, then in exFat, in HFS

• i reinstall and it’s work


after checking disk with disk utility :

En-tête de volume non valide @ 0 : I/O errorEn-tête de volume non valide @ 2000021315072 : I/O errordisk2s2 n’est pas un volume CoreStorageErreur

it seem it’s a problem with boot sector 


Unfortunately that particular variation of the WD My Book Essential is not the one on the list. While they do share the same base model name as direct members/successors within a product family, the model number of your disk drive based on your link is _ WDBACWxxxxHBK  while the model on the list marked as bootable is  WDBAAFxxxxHBK.  _

Thanks JStaff,

But mine is bootable because i did it some time but some others times it don’t want.

And disk utility says :

Vérification et réparation de la carte de partition pour « WD WDC WD20EARX-00PASB0 Media »Vérification de configuration requiseProblèmes rencontrés lors de la réparation de la carte de partitionErreur : Informations requises indisponibles lors d’une recherche interne.
Vérifier et réparer le volume « Strawberry »Vérification du système de stockageLe volume disk2s2 ne peut pas être réparé pendant son utilisationVérification du volumedisk2s2 : analyse de Volume HeadersEn-tête de volume non valide @ 0 : I/O errorEn-tête de volume non valide @ 2000021315072 : I/O errordisk2s2 n’est pas un volume CoreStorageErreur : Utilitaire de disque ne peut pas réparer ce disque. Sauvegardez autant de fichiers que possible, reformatez le disque, puis restaurez vos fichiers sauvegardés.

 And Smart Drive Dx says :

I/O Errors Count : 349 (349 / 0)

 And during the boot verbose mode says (before printing the folder with question mark or the no entry symbol) :

.Error loading kernel 'mac kernel' (0x7)

 But sometimes it work fine so i think the problem is the disk.



i have simply decided to not answer because my English is probably too bad to be understand when i ask if it’s normal i can boot but only some times with this disk

so i decided to call French support assistance :

· the first time it hung up immediately

· just after that i retry and after 5 or 10 minutes of talk it hung up again 

· so i redo once (ready to start again the same conversation with an other consultant) but the french service was too busy so i was lead to another call service (german ?)

so i create (monday 16 june) a new support case to help me to solve my problem and i receive a mail of confirmation (with the ref n°Ref # : [[XXXXX-XXXXXXX]]) saying it’s ok i will have news in 1 or 2 days but today is sunday and nothing

when i check the statut for this case it’s “open” …

French Call Center contact me (a week ago) to have more informations about my config, OS, … 

They have said to try the WD+TURBO_Installer_1_3_7 driver.

But with the data i provide (i/o error, .Error loading kernel ‘mac kernel’ (0x7), …) they have said that was a random misorder of boot memory maybe (because disk mount correctly on desktop and is accessible).

So they have decided to change my My Book for a new one.

Before receiving the new one i retry the “old” one (with WD+ TURBO drivers) and for 10 consecutive reboots i got just one bug so it’s random.