2012 cMBP + M4 SSD = unbelievably slow ML installation

Discussion in 'OS X Mountain Lion (10.8)' started by dops7107, Aug 24, 2012.

  1. dops7107 macrumors 6502a


    Mar 19, 2005
    Perth, Oztrailya
    Hi MRers,

    Brand new 15 inch 2012 cMBP, I am trying to install ML on a Crucial M4 256 GB SSD, installed in the optibay using a Nimitz caddy. I also installed 16 GB Crucial RAM at the same time, which seems to be functioning normally.

    I made a ML installation USB stick according to the various instructions around the web. No probs there.

    But when I re-boot, and select the USB stick to commence the installation, the installation process is taking forever. I mean, it says (after about 20 minutes of the progress bar barely moving) that estimated time is over 4 hours. And it's been like that for half an hour already.

    I think the SSD is fine. It mounts normally when I boot from the HDD, and I did a BlackMagic test and it was hitting 450 MB/s read and about 250 MB/s write - sounds pretty normal for an M4. System profiler says it has a negotiated link speed of 6 gbit/s.

    At the moment I will just leave it overnight and see what happens. But does anyone have any clue? This is not right - even on a HDD, it should only take 30 mins or so. Pretty sure the USB stick is fine, I have used it in a previous ML installation without dramas.

    One option is to swap the SSD and HDD over, but not desperately keen to open her up again, and I don't really understand why that might be the problem.

  2. ugp macrumors 65816


    Jan 7, 2008
    Inverness, Florida
    My m4 is in the HDD Bay but I did not have any issues installing ML on mine. Installed pretty quickly I thought.

    Have you tried swapping it into the HDD Bay just to see if the Optical bay is causing the issue for some reason?
  3. Arizor macrumors member

    Aug 24, 2012
    Mounting in the optibay is notoriously dodgy.

    I mounted my m4 in the optibay and it froze periodically, and yes, installation took AGES.

    Swapped it to the HDD bay and I've been running super fast and smooth ever since.
  4. dops7107 thread starter macrumors 6502a


    Mar 19, 2005
    Perth, Oztrailya
    Your suspicions were correct guys, thanks for your input.

    The thing never installed with the SSD in the optibay, it hanged. Swapped the drives over, and after a few hiccups that involved zapping the PRAM, it installed and is working smoothly and respectably fast!

    Bizzarre, but there you go.
  5. JGoings macrumors newbie


    Aug 4, 2012
    Winnipeg MB
    This may have to do with the two differing in speeds, the HDD bay being SATA III and Optical Bay as SATA II. I'm about to do the same process once my caddy arrives, so this is good to know! Thanks.

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