Fix­ing an un­recog­nised Fu­sion Drive

Mac Format - - APPLE TALK -

I up­graded my Late 2014 iMac to El Cap­i­tan, as­sum­ing that it would run faster and smoother. This has not been the case, so I tried to roll back to Yosemite. Some­thing hap­pened dur­ing this process and now I am ma­rooned, with nei­ther version work­ing!

I used re­cov­ery mode to erase my 1TB Fu­sion Drive, which worked fine, but the drive doesn’t show up in the OS X in­staller. In Disk Util­ity, the drive looks nor­mal but all the op­tions on the Par­ti­tion tab are greyed out. Is the disk bro­ken? Help! Carol Wo­je­w­odzki

Not bro­ken, but un­par­ti­tioned, I think. A Fu­sion Drive is ac­tu­ally two drives: a hard disk and flash stor­age, treated as a uni­fied vol­ume by OS X, but I’ve seen cases where this breaks down and so nei­ther drive is recog­nised.

In Disk Util­ity, where you see the name of the drive, you should also see a line say­ing Mac­in­tosh HD in­dented be­low it. The for­mer refers to the Fu­sion Drive, the lat­ter to the par­ti­tion on it. If you only see the for­mer, the drive isn’t par­ti­tioned prop­erly. To fix it, we will have to trick Disk Util­ity into re­pair­ing it, by de­lib­er­ately break­ing apart the Fu­sion Drive.

Dis­con­nect all other stor­age, then start up in In­ter­net Re­cov­ery mode (by hold­ing å+ç+r at the startup chime). Choose Util­i­ties > Ter­mi­nal. En­ter disku­til cs list and press ® . The long string of num­bers and let­ters next to Log­i­cal Vol­ume Group is the Fu­sion Drive’s UUID. Se­lect it and copy it to the Clip­board. Now en­ter disku­til cs

delete then a space, paste the UUID and press ® . Re­turn to Disk Util­ity. It will recog­nise that the drives aren’t uni­fied as a Fu­sion Drive and of­fer to fix it. Al­low it. You should then be able to re­in­stall Yosemite.

A couple of Ter­mi­nal com­mands should re­solve a Fu­sion Drive not show­ing up in OS X’s in­staller.

Newspapers in English

Newspapers from Australia

© PressReader. All rights reserved.