Can I put a BarraCuda 2.5" 4Tb height 15mm in iMac 4K 2017?

[albertaka]

My 4K with Fusion drive is slow; the problem is known. APFS is needed for Fusion under HS/Catalina; and HDD’s cannot work on long term under APFS, the index structure is not compatible. I am now running fom external Thunderbolt (great, fast, recommended, only a few crashes).
But in time I want to revert to an internal HDD and a NVMe.
I found a BarraCuda 2.5" 4Tb HDD. Enough for my pictures.
once I have selcted a good nvme, 1Tb for instance?: then:
1) It has a large height. 15mm; normal 2.5” height is 7mm. Can it be used?
2) Is it compatible with the iMac 4K Retina late 2017?
3) is it wise to go on in Fusion mode with 1Tb-SSD + 4Tb-HDD?

 

[Juicy Box]

APFS is needed for Fusion under HS

It isn't needed for High Sierra, HFS can be used. AFAIK, the High Sierra installation will not automatically convert a Fusion Drive nor HDD to APFS, and just keeps it at HFS.

I think HFS could also be used with Mojave and maybe Catalina, but it requires cloning, and could lead to issues when it comes to SW updates. This could be easily worked around by having a cloned back up drive in APFS to do the updates on, then clone back to the Fusion Drive in HFS. Not a seamless solution, but an easy way of not dealing with APFS on your Fusion Drive.

1) It has a large height. 15mm; normal 2.5” height is 7mm. Can it be used?

I don't have an answer for you for sure, but if you don't use the rubber surround (it probably would be too small anyways, I think it would fit.

There is a lot of space in the HDD bay, and the rubber surround is about twice the thickness of the HDD, maybe more.

You could probably use double-faced tape and just take it in there. I think the HDD bracket would fit as long as you do not use the rubber surround, but even if it doesn't, just leave it off. If you use double-faced tape, I would think that the HDD doesn't need the bracket to hold it in place.


I would wonder if this would impede airflow.

If airflow is an issue, you could remove the whole HDD bay, and tape the HDD directly to the inside back of the iMac. This could also be a solution if the 15mm doesn't fit even with the rubber surround removed.

Just remove the whole HDD bay.

2) Is it compatible with the iMac 4K Retina late 2017?

I wouldn't see why not. You can always test it externally before installing internally. I would recommend this anyways.

3) is it wise to go on in Fusion mode with 1Tb-SSD + 4Tb-HDD?

I don't see a problem with it. Some people hate Fusion Drives, but if you want a clean setup with no external drives, this is a good way to do it.

The 2.5" HDD is going to be slower than what you could get from a 2.5" SATA SSD, or a 3.5" externally, but it all depends on what you want.

If you could afford the 4TB SATA SSD, then that would be a really fast Fusion Drive. Also, APFS performance loss on HDDs wouldn't be an issue, but the cost is of course much higher.

If you don't mind external drives, then getting an external 3.5" HDD would be good. Using an external NVMe with an external HDD in a Fusion Drive could be just as fast as doing it internally, but without the hassle.

 

[albertaka]

Thanks for the elaborate reply.
I have a kit to open the iMac.
& I remember now I saw the films in which the HDD was replaced with SSD and that there was some rubber shock cushion around it.

The main reason I like the internal position is that this way the garbage can works properly.
And the occasional spinball or restart is gone.
I have an external drive already (HDD 1Tb, 2.5") and it works & is fast enough. But there is no garbage collection. Gone is gone.
Errors are quickly made in manipulating pictures and folders.
I do not have the money for a 4Tb SSD