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.
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.
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.
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