My iMac (Retina 5K, 27-inch, Late 2015) with a 2TB Fusion drive has been a little sluggish and so I already have a replacement but I do love the machine and use it a lot still. I did a test and noticed that the ssd is near death ☠️ and I am wondering if the regular drive just takes over the startup etc or is my beloved iMac going die right along the tiny ssd.... which would be a real shame. Anyone have some insight into this?
![iMac 5K 2015.jpg]( "iMac 5K 2015.jpg")
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Resolved SSD part of Fusion Drive close to death ☠️
- Thread starter ovbacon
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There's another thread here at macrumors of which the subject is (roughly), can excessive usage wear out an SSD prematurely?
Looks like your experience here provides an answer...
Looks like your experience here provides an answer...
Luckily, you can back your data up now (should be anyway), and just buy a NOS replacement SSD of whatever size you want, (I picked up a 1tb for about 300 and then a 2tb for 400, & if you’re qualified to operate a screwdriver, pop it in, restore from backup, & you’re back in action. Don’t even wait til the catastrophic failure, you’ve already got your warning that the time to toss the old SSD is now. Unlike the new models, which just go in the trash at that point (bc the entire logic board has to come from Apple which is more than the entire machine is worth), just consider changing out SSD’s with their limited lifespan to be like changing the timing chain on a car. These classic iMacs are designed to be serviceable & will run for ages with minimal (but important) periodic maintenance.
Search eBay for Polariss SSD. The 2015 iMacs run just fine on the 2015 generation SSD models and even faster on the 2019 models, boot camp & all. You take your chances with other aftermarket SSDs like WD Blacks & things, bc even though you think you’ll save $ over the Polariss, the firmware may not recognize the WD’s, & then refuse a boot camp installation or even & boot OSX poorly. This is the one area it pays to stick with the slightly pricier OEM hardware. But buying it from Apple will cost 2-3x as much, for absolutely no benefit.
Tye tutorial on how to access the SSD on your logic board is on OWC’s site, which walks you through it slowly and thoroughly. It seems daunting the first time, but when things become familiar, you can do it in about 10min and the sense of accomplishment of having taken it completely apart (& cleaned it all out) is fantastic.
Search eBay for Polariss SSD. The 2015 iMacs run just fine on the 2015 generation SSD models and even faster on the 2019 models, boot camp & all. You take your chances with other aftermarket SSDs like WD Blacks & things, bc even though you think you’ll save $ over the Polariss, the firmware may not recognize the WD’s, & then refuse a boot camp installation or even & boot OSX poorly. This is the one area it pays to stick with the slightly pricier OEM hardware. But buying it from Apple will cost 2-3x as much, for absolutely no benefit.
Tye tutorial on how to access the SSD on your logic board is on OWC’s site, which walks you through it slowly and thoroughly. It seems daunting the first time, but when things become familiar, you can do it in about 10min and the sense of accomplishment of having taken it completely apart (& cleaned it all out) is fantastic.
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Above answers are misinformed. You CAN replace the SSD, at least on the 2017 model. Yours is likely similar. In fact, my earlier research suggested that you can replace the internal SSD with a large one and dispense with the spinning drive if you want (Be sure to do your own research). I think you can even replace the CPU with a more powerful compatible one if so inclined. The hardest part is getting the glued-on display off, but I have done it successfully. You can too. Just follow some on-line guides.
I had two minis pack up due to fusion drives , they seem extremely unreliable
My iMac late 2015 has a 1tb ssd and it’s so far amazing 🤩
I know what I’d get next time
My iMac late 2015 has a 1tb ssd and it’s so far amazing 🤩
I know what I’d get next time
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Hmmmm, ok. Well I'm not worried about back-ups as it is backing up every day and the iMac's replacement is already in operation so I can play around with it.
If anyone has a good resource of how to upgrade/renew the inside of an 2015 iMac I would really appreciate it. Of course I know I can go and find tons of "how to's" out there but I'm here to get the right info and not something that ends up being incorrect.
So I guess as Freedom1 mentioned I have to go in through the front glass panel, which isn't a problem as it has a crack so I could immediately replace that as well.
If anyone has a good resource of how to upgrade/renew the inside of an 2015 iMac I would really appreciate it. Of course I know I can go and find tons of "how to's" out there but I'm here to get the right info and not something that ends up being incorrect.
So I guess as Freedom1 mentioned I have to go in through the front glass panel, which isn't a problem as it has a crack so I could immediately replace that as well.
It's just time, they fail after so much usage. I can tell you that acquiring SSD even if it is using the SATA interface is better than the fusion in operation.
As suggested get that backed up with an external SSD so you have a ASR volume to restore your settings/apps/system pref from sooner than later.
The take apart to install the drive is not that difficult, but this is one of the older designs and can be impacted by ESD risks.
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That video is very helpful but it is really about replacing the HDD with an SDD, which is a awesome suggestion but I am wondering now if I would still need to replace the smaller ssd that was part of the fusion drive or can that be circumnavigated by using a sdd instead of the hdd.
The front glass is not a separate item, but is actually glued to the LCD panel. So you'd need to replace the whole thing (both the glass and the LCD panel) which is pretty expensive, although you may be able to find used working ones on eBay for less. There are some videos out there on how to remove the glass from the LCD panel, but replacing just the glass is something I've only seen people with specialized equipment do.
I found that it is possible to replace the glass separate from the "LCD panel" but that you need specialized equipment to do so and if never done before can be very difficult. By that time it is easier to just replace the whole thing.
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No one seems to have mentioned this, and I apologize for not having adequately brushed back up on the subject before replying, but I recall there's at least one built-in utility for reassigning the roles of the built-in drives that were originally set up as a Fusion Drive. For example, you can just "un-Fusion" the Fusion Drive and let the Finder treat the two disks as two disks. (I did look all this up once to perform some operations on my own similar iMac. Something to do with the Terminal, or maybe something in Disk Utility. Or both. At the least, I think I can tell you that you can only perform these operations when you're not using either of the disks as a startup disk. I think you might be able to continue just using your iMac with the large spinning drive and without the SSD, but you'll probably need to make a full backup, boot the Mac in Recovery Mode, and erase the drive to accomplish it. Something like that.)
I think this article might be one place to start learning about this stuff: https://support.apple.com/en-us/HT207584
I think this article might be one place to start learning about this stuff: https://support.apple.com/en-us/HT207584
If the SSD fails, the HDD WILL STILL BE GOOD (hardware-wise).
However, the "logical, fusion drive" will be lost.
In that case, you can reformat the HDD as a "standalone" drive and keep using it.
You could leave the SSD "dead, but in-place".
Then get an external USB3 SSD, and set that up to be the new boot drive.
However, the "logical, fusion drive" will be lost.
In that case, you can reformat the HDD as a "standalone" drive and keep using it.
You could leave the SSD "dead, but in-place".
Then get an external USB3 SSD, and set that up to be the new boot drive.
That's basically was I was alluding to, ovbacon.
"rpmurray" originally suggested your Mac would become unusable if one drive stopped working, but I think they were assuming a situation that didn't involve a utility like this having successfully performed an operation like that beforehand.
There's the question of what will happen if you SSD does fail and you haven't performed an explicit split or taken any other preventative measure. Will macOS recognize on its own that the SSD is unavailable and salvage things by regarding the surviving hard disk as the single available one? I don't know, and there must be a real answer and some documentation about it someplace.
"rpmurray" originally suggested your Mac would become unusable if one drive stopped working, but I think they were assuming a situation that didn't involve a utility like this having successfully performed an operation like that beforehand.
There's the question of what will happen if you SSD does fail and you haven't performed an explicit split or taken any other preventative measure. Will macOS recognize on its own that the SSD is unavailable and salvage things by regarding the surviving hard disk as the single available one? I don't know, and there must be a real answer and some documentation about it someplace.
just get an external SSD to boot from before the internal set up fails.....it's the easy solution to your situation.
Using an external SSD is going to be so much simpler than replacing the internal failing set up.....and you can get a decent price on a 2TB SSD if you want
Thanks everyone for pitching in with the info you've all given. Of course any other/more info is more than welcome but at least I have a better understanding of what some options are to keep using the iMac (it would just be a bummer to toss it). Since I had a friend who was kind enough to drop something heavy right on top of the screen there is a pretty long crack in the glass and I'd rather not open it with the risk of having to completely replace the screen if it gets damages even more.
So the option of salvaging the HDD by splitting the Fusion seems like one that might save me a lot of headache. But first get use an external drive to boot from 👍
So the option of salvaging the HDD by splitting the Fusion seems like one that might save me a lot of headache. But first get use an external drive to boot from 👍
I'm not sure I know how to read a drivedx report on a fusion drive. It looks like the first part is the SSD and the 2nd the HD.
The SSD part shows an overall health rating of 96.5% which is in conflict with the SSD Lifetime Left indicator. Unfortunately the Data Units Written is not shown.
Also interesting is that the power on times are differrent - ~57k vs ~34k hours. Shouldn't they be the same?
What does health indicators show?
The SSD part shows an overall health rating of 96.5% which is in conflict with the SSD Lifetime Left indicator. Unfortunately the Data Units Written is not shown.
Also interesting is that the power on times are differrent - ~57k vs ~34k hours. Shouldn't they be the same?
What does health indicators show?
I actually started wondering myself how and what is exactly indicated/tested by DriveDX. As shown in the test image the overall health rating is 100% (good) but the lifetime indicator is bad. There are no errors on the ssd. I'll add some more ss of the test. One thing I did notice in the activity monitor (this is not something I look regularly at) is that there is always around 1.20GB of swap being used. I don't know if this is a good, bad or normal thing but I've seen a lot of discussion around it.
And yes.... in the top in the initial image is the ssd and the bottom the hdd.
Could you post those without those messages obscuring the wear leveling count numbers? The SSD appears to have more than 6 years of Power On Time and is only 128GB as compared to the 2TB HD. Since the SSD in a Fusion drive acts as a large cache for the HD I'm assuming that there's been a lot of read/writes to get the wear leaving down to almost nothing.
Looks as if the wear leveling table cells are close to being exhausted but the rest of the SSD itself is fine? Not sure how the 2 interact when the former fails.
How Wear Leveling Increases SSD Lifetime
By evenly distributing the P/E cycles among all blocks, SSD Wear Leveling increases the lifespan of flash storage and increases its dependability and durability.
I would make sure your 3-2-1 backup strategy is in place. Getting an external boot SSD does seem like a good idea since it would likely give you better performance as well.
Not exactly sure how to read the Wear Leveling Count values since they don't appear to be especially bad, but the Host Reads MiB/Host Writes MiB are approximately 150 to 200 TB each. I suspect that that much traffic going through the bottleneck of a 128GB SSD being used as cache are going to wear it out after six years, since the way a Fusion drive works requires the shuffling of a lot of data on the SSD, increasing the write counts on the pages.
I suspect that Apple expected people to landfill the iMacs before this happens.
As for a solution I just want to be clear that the data on the iMac is of no importance. Everything has been backed-up for years and it is already migrated to a new machine. I just really hate to scrap this thing and like to keep using it for some design work some F1 watching etc...