Chosen Solution
My late 2012 27” iMac has been randomly crashing and hanging up, so I ran the Apple Hardware Test, and the result was 4HDD/30/40000005: SATA (1,0). I have a Fusion drive, and I’m assuming this means the HDD is bad, but I can’t find any official source for reading these codes. First Aid run through the Disk Utility yields clean results, so I am having trouble figuring out what’s really going on here. I was planning to replace the HD with an SSD (Samsung 860 EVO 1TB), but the Samsung EVO 860 1TB really slow in testing have been far worse than the current Fusion drive, so I’m at a loss for the next steps that should be taken. Thanks!
Yes, the diagnostics won’t test your HDD discreetly it only sees the Fusion Drive set so the PCIe connected SSD cache is hiding the SATA testing. You would need to break the fusion set to properly test the SATA drive. I think it’s safe to say the HDD drive within the Fusion Drive set is failing here. I’m not a fan of Fusion Drives, I prefer discreet drives and I love PCIe/NVMe drives. While I understand you need to move forward here, you will still be limited to the SATA III (6.0 Gb/s) connection. The small PCIe drive is useless by its self and you won’t gain any performance setting up a dual SSD Fusion Drive.
