Fusion Drive problems/LiteOn SSD not recognized as Solid State

[Crazor]

Since my WD RED died on me a few days ago, I had to rebuild my Fusion Drive setup. At first, I was using a LiteOn LITEONIT LCT-128M3S 128GB SSD and a Seagate Barracuda 1.5TB HDD since 10.8.3 came around, and soon upgraded to a WD RED 3TB. I verified that the Fusion Drive was more than a JBOD array by using iostat and dd to read and write stuff. I saw the "4GB write cache" behaviour as well as the "moving blocks to SSD after reading them often" behaviour, so I concluded that my Fusion Drive was working fine. I upgraded my system from 10.8.3 up to 10.11 just fine.

 

Skip to now, the WD RED died and was replaced by another 3TB WD RED, same model in fact (WD30EFRX-68EUZN0). Only this time I noticed that diskutil in Yosemite and El Capitan showed "Fusion Drive: no" when querying the drive for information (El Cap's Disk Utility GUI said it was Type: Fusion Drive, though). This made me wonder what happenend. I've since tried to recreate the Fusion Drive from 10.8.3, 10.9, 10.10 and 10.11, to no avail.

 

Funny thing is: Using the exact same USB thumbdrive with 10.10, I set up a buddy's 2011 iMac which I upgraded with a SSD a few weeks ago. His Fusion Drive is said by diskutil to be "Fusion Drive: yes". I haven't verified it working with iostat and dd yet, but I plan on doing so soon. My Mom's iMac also got the Fusion Drive treatment a few months ago, running Yosemite. Everything appears to be fine with it, too.

 

I noticed that 10.11 Disk Utility (GUI version) seems to think that my SSD is a HDD. When looking at the disk's info, it says "Solid State: no", even when I delete the whole CoreStorage shebang. Also I had wondered why there is no more TRIM info in System Profiler since I upgraded to Yosemite, but I figured that that information has been omitted after all the TRIM discussion.

 

So maybe this is the cause for my Fusion Drive problems? How can I convice OS X that my SSD is in fact a Solid State Drive? Maybe OS X is looking for the string "SSD" in the device's name? Can I change the name with Clover? I remember patching the SATA driver to look for "SSD" instead of "APPLE SSD" to enable TRIM in previous versions of OS X, maybe this problem is related?

[Crazor]

So I think that the problem is caused by the system not recognizing my SSD as an actual Solid State Drive. I researched a bit about how the OS can detect an SSD, and found out about the ATA8-ACS standard: A drive that reports 1rpm as the rotational speed is to be considered a Solid State Drive (this is the way Windows >= 7 disables online defrag, btw, and is required behaviour for SSDs to conform to the Windows Logo program). 

So I installed smartmontools, and of course smartctl -i does report my drive as an SSD, and from looking at the raw data the drive returns when queried, I found out that it does report as 1rpm.

Also, I played around again with every major OS X release starting from 10.8.3 and up until 10.11 and had a look at what the system thinks of my SSD when I install OS X on it, without creating a FUD. Every version does report my SSD as "Solid State: no", and the various TRIM enabling hacks (patching the kext, running trimforce on recent versions) don't work for this drive (although they had before).

This is soooo weird!