Why does my SSD disk on OS X work with a USB-adapter but not over internal SATA?

Question

I'm trying to replace the HD in a MacBook Pro (2009) with a Samsung SSD 830. The SSD has previously been used in a MacBook (late 2008, aluminium) without issues.

Since very little differs in the specification for the two computers, I just installed the drive and booted. It worked for a while, but after a hard reboot (due to other issues) it started to behave strangely, processes were locked up, and I couldn't shut down cleanly. I tried to reinstall Mac OS X v10.8 (Mountain Lion) over the existing installation, but it would not complete. I then erased the disk through Disk Utility and tried a fresh install, without any luck. I'm able to partition it, but the installation locks up.

I then removed the drive and connected it to another Mac with a USB-to-SATA adapter. Over this connection I was able to install OS X. When I tried the same with the MacBook Pro, the whole installation completed successfully, so I reinstalled the drive inside the computer and booted, and it seemed to work until I ran migration assistant, which failed. (The syslog was full of errors of core processes that couldn't read from "(null)".) I then tried to use rsync to transfer my data, but I got a write error followed by "broken pipe". Just to check I removed the drive again, connected it over USB and run rsync again, without issues.

I have yet to try it inside the original MacBook again, but so far my experience is that it works when connected over the USB-to-SATA adapter, but not over the internal SATA connector in the MacBook Pro. The S.M.A.R.T status shows no problem. What could possibly be the reason?

Answer 1

I'm afraid I can't specifically tell you why it didn't work from one machine to another, only that I have had the exact experience you describe with a Kingston SSD (V200/256 GB), in similar machines (15" aluminium MBP and 13" 2009 unibody MBP).

I have a feeling it was due to some interaction between built-in garbage collection on the disk and something the OS was doing. This based purely on the fact that the locking up was fairly random, in both occurrence and length, but it seemed more frequent during heavy disk access (in particular, activities you mention - installing the OS and rsync'ing data back into place).

Over USB the disk was fine, presumably because OS X treats a USB mass storage device differently from an internal SATA device.

Unfortunately, the remedy in my case was fairly extreme: I spoke to Kingston and they kindly replaced the drive with a V+200/240 GB. Slightly smaller, but more modern controller and totally stable (a couple of months now).

Looking at the specifications for the Samsung 830, they use a differently-named controller from the V200/256 GB, so this isn't necessarily the same issue, and likewise the Samsung 840 uses a different controller from the V+200/240 GB, but I figured it was worth letting you know that there may not be a solution to this problem.

(N.B.: I tried turning TRIM on and off on the OS using various patches available online, but it didn't seem to make any difference.)