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Fusion Drive Failed, Questions on SSD Upgrade

lpretorius

lpretorius

macrumors newbie
Original poster
May 17, 2019
4
0
South Dakota
Hey all, a couple of days ago my fusion drive in my late 2015 iMac toasted out on me... I received the dreaded prohibitory signal and after a long phone call with Apple support it seems as though the hard drive portion has died while the 128gb SSD is still ticking. After doing some extensive reading on the forums here I have decided to replace the hard drive with a 2tb Samsung 860 EVO SSD on my own. I have the drive, OWC install kit and bracket on order to arrive Monday. iFixit.com and this website have given me pretty much all the instructions I think I need to install the new drive... However, I'm not too sure what to do once its installed!

So currently I have El Capitan installed on the small 128gb SSD. I also put a recovery install onto a jump drive. My questions are: Should I boot from the usb drive and format/delete both the SSDs? Should I completely disregard the smaller SSD from now on and only use the new Samsung one, or should I install the OS on the smaller original SSD? What about any apps that I install? Is the built in SSD slower/faster?

I'm also really not sure how to tell the mac where to save files/programs from now on as the fusion drive just kind of took care of everything... Is there something that I need to do to combine the two? Or should they be split up somehow? As you can see, I am very much a novice and have no idea what to do once I get the new drive in. I appreciate all your help! Any other suggestions/tips that you may have please feel free to share!
 
The SSD component of your failed Fusion Drive is going to be faster than the Samsung 860 EVO SSD because the EVA is limited to a SATA 3.0 (600MB/s) maximum. The SSD that Apple uses is a PCIe blade (Apple OEM Part #SSUBX) on a PCI 2.0 x4 connection. While the 128GB version will not be as fast as a larger PCIe SSDs sold by Apple as BTO options, it should still be able to beat the Samsung. You can look at BlackMagic Disk Test as a gauge of how fast the drive is and get some anecdotal data, however, the Samsung may end up being fast enough to put all your data on as it is much larger and will have quite a bit more free space, which is always good with SSDs and they do not tolerate being short on space. If you can live with the 128GB PCIe blade and keep it restricted to just macOS System and Application files, then you should be just fine with having your Home folder on the 860 EVO. Just my 2¢.

Source: https://arstechnica.com/gadgets/201...-driving-a-fully-loaded-4000-27-inch-5k-imac/
 
Dirty little secret: Apple used an NVMe 2 blade that's half as fast as the 3 x4 PCIe bus in the 2015. You have the opportunity to do a bit of hotrodding here.

Install a NVMe 3 x4 blade. The Samsung 970 EVO is a good, fast choice with 2TB costing $500 — smaller sizes are less. Plenty of threads on this. You must have High Sierra or Mojave to run an NVMe 3 x4 blade on an iMac. Not all 3 x4 blades are equal—some top out at 1500 R/W but the 970 is rated over 3000. All need a pin-out adapter except the OWC Aura Pro X2 which is a direct fit and very fast but it's a bit more expensive.

If you go 2TB, no reason to remake the Fusion drive—use the 860 for storage and your iTunes. If a small SSD, then tie it with the 860 as an FD for best performance.

I have a small stash of 128GB NVME and NVMe 2 blades that I've pulled from iMacs and MacBooks over the years. Nobody wants.
 
I am certainly learning a lot! I ended up watching a couple of videos on replacing the NVMe SSD and am now seriously considering it since I will be opening the Mac up anyway... It definitely looks a bit more involved but if you are careful and take your time it should be hopefully go smoothly. From the videos I watched it looks like basically you remove most of the components to get to the SSD and then simply insert the new one then put everything back together?

Any other NVMes that you would recommend that are a bit less expensive? I already have the 2TB SSD arriving in a couple of days so I am thinking 128 or 256 should be okay for my uses if it indeed is noticeably faster than the built in NVMe.
Thanks again!
 
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Get the largest NVME you can afford also check the speed. As some have mentioned some only do 1500, while others go to 2500 or so.
I used an intel 660p, cheap but will probably last me until I get rid of the machine.

Take your time and pay attention. There is a picture of the screws and description of where they go. Print it out and put some double stick tape on it so you can keep track of them.

Good luck.
 
lpretorius said:
I am certainly learning a lot! I ended up watching a couple of videos on replacing the NVMe SSD and am now seriously considering it since I will be opening the Mac up anyway... It definitely looks a bit more involved but if you are careful and take your time it should be hopefully go smoothly. From the videos I watched it looks like basically you remove most of the components to get to the SSD and then simply insert the new one then put everything back together?

Any other NVMes that you would recommend that are a bit less expensive? I already have the 2TB SSD arriving in a couple of days so I am thinking 128 or 256 should be okay for my uses if it indeed is noticeably faster than the built in NVMe.
Thanks again!
Click to expand...

The Intel 760p has better endurance and performance than the 660p, as the other poster recommended, but it really isn’t any more economical than other TLC NAND SSDs. You can find Apple’s SSDPOLARIS for sale out there if you want to have an OEM NVMe drive that will 100% work in your 2015 iMac. The cost for the 128GB and 256GB SSD are somewhat palatable, but beyond that, the cost goes up exponentially.

I would not waste time making a Fusion Drive, but would use the long Sintech Adapter with an Intel 660p or 760p, which seem to work the best.
 
So I was doing a bit more research and stumbled across an article on beetstech.com that says all of the late 2015 iMacs already have the NVMe 3 x4 blades in them with exception of the A1418 model, but it looks like mine is the 1419 model (iMac Core i5 3.3 27" Retina 5k late 2015). This is all new to me so I'm not 100% sure, but perhaps according to the article I already have the faster blade and it wouldn't be necessary to go through the extra swap? Perhaps I am just reading the article wrong...and perhaps I am looking for excuses to not have to dig deeper into my Mac for this swap, lol Thanks again for your help!
 
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Ater more consideration I'm trying to talk myself into adding the Samsung 970 EVO in the 1TB size. I was also reading about the Sintech adapters and noticed that they have the following listed on their Amazon listing: "Support Samsung 960 or 970 EVO(Risk of Random Kernal Panic)". Is this something that anyone has experienced? I'd hate to do the extra work to find that the new blade would cause more of a headache than just swapping the HDD for an SSD...
 
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