Speeding up my 16TB HDD with Fusion Drive

[maestrox]

Hello everyone,

I'm a media composer. I am using BigSur, my system is installed on 2TB m2 SSD.

I want to speed up my 16 TB Exos Seagate sound library archive with another 1 TB m2 SSD via FusionDrive. So I will not install an operating system.

Since "cs storage" is not working in BigSur anymore, I connected two disks to another computer and applied the following commands via HighSierra at terminal. And I created a FusionDrive. (I guess)

diskutil coreStorage create myLogicalVolGroup /dev/disk1 /dev/disk2 (SSD first)
diskutil coreStorage createVolume lvgUUID jhfs+ "Fusion 100%

But at this point, I want to confirm if I did it right, before I loaded the whole backup.

What I want is to use 16TB of space and speed it up with a 1TB SSD. But I'm not sure if I did it right by marking 100%. I mean the part I'm stuck with is the last percentile. It was 17TB of space. In other words, I didn't understand whether the speed will decrease after passing 1 TB. I want the SSD to have an effect on the entire disk, like a kind of cache.

Thank you.

 

[ignatius345]

Years ago I did a DIY Fusion Drive in my old Mini. It worked brilliantly and proved quite durable. I haven't heard of using a Fusion Drive on a non-startup volume! I hope it works out for you.

I do recall that when I was setting mine up, there was some Terminal command that would reveal whether files were being migrated to and from the SSD part of the drive automatically as they should.

Long term, though, I do wonder how long Fusion Drives will be supported in the OS. I don't know if any are even configurable on new Macs at this point. But I suppose you can cross that bridge when you come to it.

 

[maestrox]

I do recall that when I was setting mine up, there was some Terminal command that would reveal whether files were being migrated to and from the SSD part of the drive automatically as they should.

Thank you. Do you remember this Terminal command ? I think, it would be great for me.

 

[ignatius345]

Thank you. Do you remember this Terminal command ? I think, it would be great for me.

I do not, sadly, sorry! It's been quite a few years. I may have found it on StackExchange, though -- that was a useful forum for technical stuff.

 

[Brian33]

I had a corestorage DIY Fusion drive with 500GB SSD and 2TB HDD, and it was wonderful (it was my boot drive). After setting it up I verified it was working as expected with the 'iostat' command. My method may not be as practical for you because it involves filling the SSD, but here's what I did:

Use diskutil list to get the device IDENTIFIER of each part of your Fusion drive.

Run this command in Terminal.app, replacing the '2' and '3' with your Fusion disk numbers: iostat -d -w 2 disk2 disk3

Now, copy more than 1TB to the Fusion drive. Watch the 'iostat' output. The first 1TB will show high MB/s transfer rates to the SSD device number. After the SSD portion of the Fusion drive fills up (actually, a 4GB buffer is left empty), data will be written to the HDD device, and you will see a sudden drop in the MB/s transfer rate.

This proved to me that the Fusion drive was operating correctly. Once the SSD is full, you can re-test with a 5GB file (for example), and watch the 4GB be written to the SSD buffer, and the remaining 1GB to the HDD. Great fun!

Also: I haven't tried yet, but I believe you can set up a DIY Fusion drive on Big Sur using APFS. I don't recall the exact commands, but they would start with 'diskutil apfs....' It's on my list of things try out -- I loved my old Fusion drive's performance and convenience! Good luck.

 

[Fishrrman]

Somethin' tells me this isn't going to work as well as the OP hopes.

If the sound samples are residing on the HDD media, turning the drive into a part of a fusion drive isn't going to make them "get read any faster" from the HDD drive.

You'd do better to get 2 (or more) SSDs, and "RAID them" using a multi-drive enclosure.

 

[maestrox]

Thank you guys! @Brian33 @ignatius345 @Fishrrman


You know that high-storage SSDs are very expensive. (At least for now.) Of course, I would prefer to buy SSD if possible, but for 16 TB sound libraries, I have to follow alternative way.

In fact, there is a system called PrimoCache that does this on the Windows side. The logic is very simple. The application redirects one disk to another disk as a cache disk. That's what I thought it would be, but I guess FusionDrive isn't a system that will provide that much. Right ?

I'm open to your suggestions. Thank you.

 

[ignatius345]

In fact, there is a system called PrimoCache that does this on the Windows side. The logic is very simple. The application redirects one disk to another disk as a cache disk. That's what I thought it would be, but I guess FusionDrive isn't a system that will provide that much. Right ?

As far as I'm aware, that's pretty much what the Fusion Drive does. The Finder and installed applications see the two drives (SSD and HDD) as a single drive. As you work with files, the Fusion Drive moves them onto the SSD automatically behind the scenes. Files that aren't actively being used get moved back over to the HDD as needed to make space on the SSD for active files. I guess that's basically a cache, right? But this is built directly into the OS on a deep level. No extra applications necessary. To you and the software you use, it's invisible.

The only hitch I'm aware of with this is that the SSD can see a great deal of read/write activity. On some Macs, Apple severely skimped on the SSD (as low as 32GB, I believe) and that tiny drive could end up wearing out early. This actually happened to me on my iMac 5K -- even with a full 128GB SSD as part of its Fusion Drive. By the time I replaced it, the disk utility I was using was estimating just 5% lifetime left after about 4 years of use.

If you're using a full 1TB SSD, though, that would help a lot. As always, you have to be sure you have a good backup of everything -- especially when your new Fusion Drive has two points of potential failure: the HDD and the SSD. If either breaks, your volume is ruined and your data will be lost. But as long as you maintain good backups you'd have something to fall back on.