2019 imac fusion drive

[BatSam]

Hi mac gurus! I have a question and I was wondering if it is possible. I have 2019 27" 500gb SSD, 8GB ram, 5k iMac. I have 3tb personal data sitting in an external (exFAT) drive copied from my previous pc. Also, I have prepared 12tb Raid0 with Akitio Thunder3 Quad X drive ready to be used. It is empty sitting next to the iMac.

My query is it possible to create a fusion drive using the above mentioned 2 drives, my raid0, and the iMac internal SSD? I'm trying to avoid dealing with different drives for my storage needs. I tried moving my Home Directory to an external drive before, but the iMac started mildly misbehaving so I reverted it. Smooth factory-like system integrity and easy to use fast/large storage is a priority of mine.

My data is mostly videos and photos.

Waiting for that day when 6tb SSD is cheap and mainstream... lol


Best,

 

[pm-r]

My query is it possible to create a fusion drive using the above mentioned 2 drives,

I have no idea, but I do know most things are possible given enough time and money.

Why not start with a Google search, something like:
mac how to create fusion drive
mac how to create fusion drive - Google Search

Smooth factory-like system integrity and easy to use fast/large storage is a priority of mine.

What's wrong with a tried-and-true raid system

I know nothing about them either but I'm told they're fast and smooth... and reliable ...



- Patrick
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[MacInWin]

Fusion drives, even the totally internal ones, are not as reliable as either SSDs or spinner-HDs. The reason is that a fused drive is a combination of the two. And a failure of either is catastrophic to the fused drive overall. So if you have a drive that is 99% reliable and an SSD that is 99% reliable, the fusion of the two will be about 98% reliable (99% times 99%). Add in the unreliability of the fusion software (no software is 100% reliable) and the product is never going to be as reliable as each component. Now add in the unreliable cabling to reach an external drive, the unreliability of the external power supply, control boards for the interface and the ports on both the iMac and external drives and the reliability of a monster made that way will be way to risky for my taste. Any glitch in the communications/power to the external drive and everything is gone. I have enough trouble accidentally nudging a USB cable and getting the warning about not unmounting before disconnecting the drive. If I had a fused drive, that message would mean I just lost everything on both drives.

In any event, to fuse a pair of drives they both have to be in the same macOS format, so it probably won't work with either of his externals as they currently exist.

In the case of the OP, what may be better is to copy his files from the FAT drive to the RAID drive temporarily, then reformat the FAT drive to macOS format, then copy the files back from the RAID array to that newly formatted drive. Now copy his Home directory to that same drive and start cleaning out his directory, but leave the directory in place. There are hidden files in the Home directory that some applications expect to be there and that software sometimes does not look anywhere else. To work on files, either work with them from the external drive, or if that is too slow, move them to the internal drive, do the work, then once finished copy the result back to the external and erase from the internal. Given that the OP's objective is

Smooth factory-like system integrity and easy to use fast/large storage is a priority of mine.

the best way to do that is to leave the Home directory where it is and to avoid making a Frankenstein monster that is going to have reduced reliability.

 

[gsahli]

Sorry for joining the conversation late...
I have moved my standard MacOS data/document folders to a second drive using symbolic links. Here's an example:
How to use symbolic links in macOS to load balance your data | iMore
I have kept my Home folder on the SSD for fast access of settings/profiles files (these are mostly hidden files), but have linked my Documents, Music, Pictures, Movies to copied-over folders on the spinner drive. Have been using this scheme for years.

 

[MacInWin]

@gsahli, I tried that for a while, but gave it up. What was happening was that I was opening new documents, just putting them in the Home directory on the internal drive and not remembering to do the move/link to get them off the internal. So the internal had some, the external had others. Then when I went portable (MBP), carrying around the external just made no sense at all, so I quit and now just put things on the internal. When it gets too much on it, I cull the folder to the external, but no links back. Just made life easier.

That said, for an iMac or Mini your approach would be brilliant and would definitely work.

 

[AMACL]

Fusion drives, even the totally internal ones, are not as reliable as either SSDs or spinner-HDs. ...If I had a fused drive, that message would mean I just lost everything on both drives.

Wow, that sounds nasty. I just bought a new iMac with a Fusion drive because it was touted as fast and cheap. Are you saying there's no free lunch and that that drive is at more risk of failing catastrophically than the old disk drive or the SSD in my Macbook? If it's only 2% riskier, I can live with that.

 

[MacInWin]

It's not even 2% riskier, but it is riskier. The risk comes from the fact that to have ONE drive work, TWO devices have to work. And each has a certain failure rate. The fusion means that unlike having an SSD and an HD separate, if either one fails, both fail, or appear to have failed, because the system stores things on both drives all intermingled. And, nope, no free lunch. If you want speed, go SSD. If you want cheap storage, go HD. Fusion is an attempt at speed AND storage at the higher risk of failure. Just make backups frequently, you'll be ok.