DShelbyD

Q: how to clean-install Mavericks to a fusion drive?

Because I cannot find a complete answer here or anywhere else, I seek information about reinstalling Mavericks on a 1TB fusion drive on my late 2013 iMac. I see discussions about reinstalling, backing up data, Boot Camp issues, rebuilding a fusion drive, making a fusion drive from scratch, and the like; but I do not find the level of detail I am seeking about starting over with a fusion drive. I upgraded to Mavericks from Mtn Lion and now see hints that I needed to do something special to take advantage of the properties of this drive.

 

That said, here are my questions:

 

(1) When I "Command-R" reboot to Recovery and get to the Disk Utility, I see a separate 1TB HD as an extended partition as well as a 125GB drive that is root (/), which I presume is the SSD. To accomplish the clean installation, do I format BOTH? Or will formatting only the 1TB HD suffice? Does formatting only the 1TB HD also take care of formatting the SSD? Maybe it's not advisable to format the SSD ...?

 

(2) Does the downloaded Mavericks installer loaded onto a USB stick using DiskMakerX have the capability to do this clean install properly? or is it necessary, in order to take advantage of the fusion drive properties (SSD+HD), to download Mavericks Installer after wiping the HD so that support for the fusion drive is maintained?

 

(3) Because I am curious, where does OS X (I mean the OS, not data) reside after the installation is done? on the SSD? on the HD? I ask this because I have read that "the OS remains on the SSD," but, seemingly in conflict, that the SSD is for quick access to frequently used programs and data. Both could be correct.

 

Sorry for the length of this. And thanks.

iMac (21.5-inch, Late 2013)

Posted on Feb 19, 2014 8:13 AM

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Q: how to clean-install Mavericks to a fusion drive?

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  • by DShelbyD,

    DShelbyD DShelbyD Feb 21, 2014 7:33 AM in response to DShelbyD
    Level 1 (4 points)
    Feb 21, 2014 7:33 AM in response to DShelbyD

    As someone used to say, "One more thing."

     

    I said above (4th para from end), "... it does appear that after a USB boot, DU sees items separately, including the main storage (Macintosh HD), the Recovery partition (disk4-used also for creating the USB stick installer), and OS (disk5). Some of this layout may hold true with a "Command-R" boot from the Recovery partition, and I know I've looked at it but for the moment cannot recall the information."

     

    Here is confirmation (as it appears to me) that the SSD is seen separate from the HD in a Recovery boot (Command-R). It is a screen shot of Disk Utility after such a boot:

     

    Command-R_DU.png

  • by LowLuster,

    LowLuster LowLuster Feb 21, 2014 7:51 AM in response to DShelbyD
    Level 6 (12,074 points)
    Feb 21, 2014 7:51 AM in response to DShelbyD

    The TOP entry on the left is the internal Drives, the Core/Logical Storage Volume (The two dirves combined to look as one). The Top Macintosh HD entry. The second Macintosh HD entry is the Partition of the Core/Logical Volume (You always need a partition and that partition has to be formatted so you can install OS X). If you highlight that top entry it should read, at the bottom, Logical Storage Volume (or something similar). So your FDS is in tact.

     

    In your second screen shot everything below the line, below the greyed out Superdrive entry, are External Disks you have connected to the system. Disconnect all of them before you try doing the reinstall of OS X (That is unless you plan on booting from one of them that holds the Mavericks install files. All others disconnect).

     

    In the Diskutil list entries you'll notice both the Disk 0 and 1 have Apple_CoreStorage listed. That is the 2 drives making up the FDS and the third entry, disk 2, lists the total amount of disk space available in the FDS. To terminal is appears as a separate disk.

     

    Once you boot to the recovery HD system, Whether from the Mavericks external install disk or from the built in Recovery HD on the internal drives, Open Disk Utility and you highlight the second Macintosh HD entry, the one that is indented slightly, on the left and select the Erase tab. Then click the Erase button. That will wipe out all data on the FDS and make it ready to reinstall OS X clean and fresh. Once that is completed, only a few second (NOTE: Do NOT select any of the Secure Erase options. That is not good for SSDs), then exit DU and select Reinstall Mac OS X and or if you have an external containing the correct install files of Mavericks for your model Mac you can restart the system and boot from that Maverick install drive. At that point you'll go through a few option screens, like inputting your Apple ID and password and selecting which disk to install to. You will select Macintosh HD.

  • by LowLuster,

    LowLuster LowLuster Feb 21, 2014 8:08 AM in response to DShelbyD
    Level 6 (12,074 points)
    Feb 21, 2014 8:08 AM in response to DShelbyD

    You are highlighting an EXTERNAL disk in that screen shot. your internal disks are at the top. The Macintosh HD entries. The Top most is the Core/Logical Storage Volume, both separate physical disk drives combined to look like one physical disk.

    The second Macintosh HD is the Partition of that core storage volume.

     

    Those are all EXTERNAL disk. Disconnect them. The only one that may not be an external is the one that is listed as OS X Base System. That is the Recovery HD and appears as an external because all files used to boot the system are loaded into RAM, IE a RAM disk of sorts.

     

    The SSD is NOT seen as a separate drive. The TOP most entries are the Internal drives combined into the FDS.

    The Top Most Macintosh HD entry

     

    If the 2 drives were separated, the FDS broken up, you would see two distinct entries at the top. One for the SSD and one for the rotating HDD.

     

    Your SS, My highlighting.

     

    Command-R_DU.png

     

     

     

    DShelbyD wrote:

     

    As someone used to say, "One more thing."

     

    I said above (4th para from end), "... it does appear that after a USB boot, DU sees items separately, including the main storage (Macintosh HD), the Recovery partition (disk4-used also for creating the USB stick installer), and OS (disk5). Some of this layout may hold true with a "Command-R" boot from the Recovery partition, and I know I've looked at it but for the moment cannot recall the information."

     

    Here is confirmation (as it appears to me) that the SSD is seen separate from the HD in a Recovery boot (Command-R). It is a screen shot of Disk Utility after such a boot:

     

    Command-R_DU.png

  • by DShelbyD,

    DShelbyD DShelbyD Feb 21, 2014 11:19 AM in response to LowLuster
    Level 1 (4 points)
    Feb 21, 2014 11:19 AM in response to LowLuster

    You said the highlighted entry was an external drive. I wondered about that. With the machine off, I disconnected the external drive, the DVD burner, and, just to be ridiculously cautious, the audio plug. I started the iMac with Command-R and went into Disk Utility. Here is the screenshot:

     

    Command-R_DU_wo.png

    This leads me to believe there is, in fact, an entry for the SSD separate from the Macintosh HD. It's the residence of the startup partition and it is the same descriptive material that appeared in my "one more thing" note above. And just to be clear about my HD, it is a factory-installed fusion drive.

     

    Here is the output of "diskutil list" after booting back into Mavericks with the same items disconnected as above in this note:

     

    /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                        *1.0 TB     disk1

       1:                        EFI EFI                     209.7 MB   disk1s1

       2:          Apple_CoreStorage                         999.3 GB   disk1s2

       3:                 Apple_Boot Recovery HD             650.0 MB   disk1s3

    /dev/disk2

       #:                       TYPE NAME                    SIZE       IDENTIFIER

       0:                  Apple_HFS Macintosh HD           *1.1 TB     disk2

  • by LowLuster,Helpful

    LowLuster LowLuster Feb 21, 2014 11:49 AM in response to DShelbyD
    Level 6 (12,074 points)
    Feb 21, 2014 11:49 AM in response to DShelbyD

    What you have highlighted in the last SS is the Recovery HD Disk. It always shows as another drive because when booting to it all the files needed to run the system are loaded into a RAM disk making the system see the RAM disk as another drive. That is not the SSD. The SSD is in the Core Storage volume as it is listed in the diskutil list entry. It is right there

    /dev/disk0 = SSD with a total storage capacity of 121GBs, entry 2: of /dev/disk0 Apple_CoreStorage. Part of the FDS

    /dev/disk1 = Rotating HDD with a total storage capacity of 1TB, entry 2: of /dev/disk1 Apple_CoreStorage. Part of the FDS

    /dev/disk2 = The actual Fusion Drive with a total storage capacity of 1.1TB and the partition name of Macintosh HD. 1TB Rotating HDD + .121TB (121GBs) for the SSD = 1.1TB

     

    Look at this way. Whatever is above the line in the left area of a DU window are Internal drives. Below that line are either external disks or Mounted DMG files and in this case a RAM disk holding the files of the Recovery system. The OS X Base System.

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