4 Replies Latest reply: May 23, 2014 12:48 AM by Stoney-Linta
chesajessica Level 1 (0 points)

Hi Everyone,


One of my clients contacted me today stating that when they try to read or mount SSD drives from Netboot, the SSD drives becomes unmounted as various, random times, and then renames itself as "disk1s1"; however, if they boot directly to their internal HDD, the SSD will stay mounted. Here are exact quotes from the client:


Essentially they just disappear or unmount seemingly randomly. A power down and reseat of the drive seems to remedy the problem for a while. Below you can see some documentation that Ben put together with some details.


The OWC Drive fails or has failed in the following ways:


(This is in new MacPros 2012, not tested in other machines at this time.)

• sometimes when a machine is netbooted, SSD drive does not mount at all and does not show in disk utility

• sometimes when a machine is netbooted, SSD drive unmounts itself at random moments; partition shows up as "disk1s2" or similar instead of the volume name (System Drive) for example

• sometimes when a machine is booted from an internal HDD, the SSD unmounts itself at random moments


I instructed them to update the firmware in one of the SSD drives and they came back with:


Even with the firmware update, the drive exhibits the problem behavior.


The failed test this time was the netboot test — with the machine netbooted the SSD drive does not mount. Sometimes, but not always, it shows up in diskutil list and in Disk Utility but only as "disk1s1" rather that the volume we have setup.


• The SSD drives always seem to mount and stay mounted if they are the boot drive.


• We are seeing the issue with multiple drives on multiple 2012 Mac Pros


Client has OWC (Other World Computing) SSD drives (240GB Mecury Electra 6G).


Any insights?




Mac Pro, OS X Server, netboot, ssd, mac pro, os x server
  • Saguinus Level 1 (10 points)

    I have a similar problem without netboot.


    I am using a Mac Pro Mid 2009 with a 240GB OCZ SSD boot disk, 2 x 1TB WD HDDs, and a 240GB OWC Electra 3G SSD.


    The current problem I have is that the SSD unmounts itself at random moments and will not reappear until reboot. The SSD has gone back to OWC once already and been replaced with a new example.


    Initially I was trying to install Windows 7 on this SSD to use as a dedicated Bootcamp volume. However, repeated installations failed, and I returned the drive to OWC. Unfortunately, the new replacement SSD just will not stay mounted (even formatted Mac OS Extended) for more than a few hours.


    What I have determined is that the SSD will stay mounted continuously when placed in an external enclosure connected via USB 2.0. Therefore, it seems that the drive is not happy on the Mac Pro SATA bus or that specific drive slot.


    I will recheck the drive in another drive slot, and contact OWC again to see if they have any ideas. Failing that, I also have an appointment at the Genius bar in a few days to bring in my Mac Pro for testing.

  • Saguinus Level 1 (10 points)

    Just to give a final update...


    The Mac Pro had its backplane replaced by Apple (under warranty).


    When I got the machine back home, I found that the 240GB OWC Mercury Electra 3G SSD would still not remain mounted. My conclusion from this was that there was nothing wrong with the Mac Pro. I then put the SSD into a MacBook (Late 2008), and the drive would not show up at all.


    I contacted OWC, and they requested a return for replacement.


    The new drive arrived here a couple of weeks ago and I have not had a problem since. The drive is still under its three year warranty.


    I hope this helps.

  • chesajessica Level 1 (0 points)

    Thanks, I appreciate the update. We got the issue resovled just a few days ago. OWC came out with a new firmware that they have applied to all of their hard drives moving forward. Our client received one of the drives with the updated firmware and they have no issues. So, sounds like you ran into the same thing as us.


    Glad it is working for you now.

  • Stoney-Linta Level 1 (0 points)

    I am using a Mac Mini late 2012 with 2 X SSDś 840 Samsung 1TB


    SSD drive THAT IS NOT THE BOOT DRIVE becomes unmounted as various, random times, and then renames itself as "disk1s1" or "disk0s1" , if you boot directly to ETHER, the SSD will stay mounted


    Recovery of drive is can only be done by rebooting and the lost of data is unavoidable


    I first suspect the SATA driver or hardware is failing but as SSD stay mounted when in a boot drive, OSX is to blame


    My last resort is a raid option still in testing