Imac keeps unmounting internal HDD?

Discussion in 'OS X Yosemite (10.10)' started by Richie Cat, Aug 18, 2015.

  1. Richie Cat macrumors newbie

    Richie Cat

    Aug 18, 2015
    Hi All,

    First post so be gentle :)

    I have a 3.4 i7 mid-2011 iMac that I recently upgraded.

    The original 1Tb Seagate drive was beginning to fail - I missed the recall program :(

    I bought a SATA kit from and installed a 250Gb Samsung SSD to boot from and also swapped out the original 1Tb hdd for a new 3Tb Seagate Barracuda. I also took the opportunity to max my RAM and now have 32Gb onboard.

    The upgrade process was seamless and the machine works beautifully and much faster..


    Every once in a while the machine unceremoniously dumps the 3Tb drive...even though it is internal/hardwired.

    I get the 'Disk not ejected properly' error and can't remount the disk unless I do a full reboot (it disappears from Disk Utility too.)

    There's no pattern, at first I though it was after a large copy operation because I was trying to put my iTunes library back onto it but it can happen randomly.

    I've tried :-

    1) Splitting the drive into 2 partitions (it loses them both)
    2) Turned off all power saver options so the disc never spins down/sleeps
    3) Running a little 3rd party script style app that writes and then updates a hidden file on there drive every 60 seconds in an attempt to 'keep alive'
    4) Raised a support ticket with Seagate (18/8) - no response so far
    5) Checked cables are 'seated' properly

    Nothing seems to work so I've come here for ideas :-

    1) Are there any really clever Terminal style commands I can use to keep the disc mounted?
    2) Are there any really clever Terminal style commands i can use to remount the disc without a reboot?
    3) Is it worth limiting the 3Tb from 6GBps to 3 or even 1.5GBps - the original drive was 1.5GBps but I believe Apple released an update that unlocked 6GBs compatibility? Even so is it 'easier' for the machine to keep a 1.5GBps drive mounted...I don't need blistering read/writes to this drive as it'll usually just hold my iTunes and be updated infrequently.
    4) Will El Capitan helps and should I just be patient?
    5) Would it help if I moved my home folder using virtual links so the 'system' is always looking for the drive?

    Hoping there a guru that can help..

  2. Taz Mangus, Aug 19, 2015
    Last edited: Aug 19, 2015

    Taz Mangus macrumors 68040

    Taz Mangus

    Mar 10, 2011
    Sounds like there could be a bad SATA cable connection or faulty SATA cable causing the intermittent unmount of the internal hard drive.
  3. BradHatter macrumors regular

    Oct 7, 2014
    I use Scannerz to test systems and typically if it's a SATA data cable you would be getting delays, maybe with an I/O error once in a while, but not necessarily ejections. Scannerz can be put into an interface testing mode that does nothing but hammer the drive interface and cables and it would tell you if the data cable was the problem. With ejections, however, it would seem to me that if there's a problem with some of the cabling it would be related to the power portion of the cable plugging into the drive not the data portion, unless the cable is really, really bad. I would think if the data carrying portions of any connected cables were bad you'd also be seeing tons of delays.

    What I would do is open the unit up, pull the hard drive and put it into an external enclosure and use it like that to see if the any of the ejections continue. If the ejections disappear it means it's either some of the cabling or something with the supply to the logic board. If the ejections continue, to me it would say either the drive isn't really compatible with the system for some reason or the drive itself is just bad.

    If you want to see a scary report about Seagate, see this:

    There's been a lot of discussion about the referenced Backblaze report so don't get bent out of shape about it, but never the less it would imply problems with Seagates may be at least a little more common than most others.

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