Chosen Solution
RAID 0 dual SSD getting way too slow! In my Macbook Pro 13" mid 2012 i7 2.9 GHz i7 with 16 GB RAM, I have 2 TB of storage (two 1 TB Samsung 850 Pro SSD’s) I’m using a OWC caddy bracket to hold the second SSD. My Macbook RAID 0 performance dropped rapidly since 2 months ago. I don’t know why, I reformatted twice, still the same. I did asked few Mac specialists with mixed feedback. Some say data problem, I’m hoping you guys can help me find the answer.
RAID 0 Mirroring does require go throughput on both SATA ports of the system. If one port is encountering problems then the performance of the RAID set will degrade. So this is what I suspect, your HD or optical SATA cable has failed. So the data stream for it is not clean causing errors which in turn slow the read or write operation. So far we have encountered a lot of failed HD cables in this series, I would start there. Here is the IFIXIT guide you’ll need to follow: MacBook Pro 13" Unibody Mid 2012 Hard Drive Cable Replacement and here is the cable you’ll need to get: MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable. Do make sure you get a new cable Vs used, these cables are fragile and you don’t want one that is already worn. See if that fixes things.
