iMac 2017 27" Fusion drive: do I need to enable TRIM or not?

[katbel]

I've been reading some articles where everyone is suggesting to enable TRIM when you are using a SSD drive
Probably I should on my older MacBook Pro (Mojave) but do I need it on my iMac with fusion drive?
I tried to see on Terminal if it was already on I'm still with High Sierra) an I got a scary Notice
after entering the command

sudo trimforce enable

IMPORTANT NOTICE: This tool force-enables TRIM for all relevant attached
devices, even though such devices may not have been validated for data
integrity while using TRIM. Use of this tool to enable TRIM may result in
unintended data loss or data corruption. It should not be used in a commercial
operating environment or with important data. Before using this tool, you
should back up all of your data and regularly back up data while TRIM is
enabled. This tool is provided on an “as is” basis. APPLE MAKES NO WARRANTIES,
EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE,
REGARDING THIS TOOL OR ITS USE ALONE OR IN COMBINATION WITH YOUR DEVICES,
SYSTEMS, OR SERVICES. BY USING THIS TOOL TO ENABLE TRIM, YOU AGREE THAT, TO THE
EXTENT PERMITTED BY APPLICABLE LAW, USE OF THE TOOL IS AT YOUR SOLE RISK AND
THAT THE ENTIRE RISK AS TO SATISFACTORY QUALITY, PERFORMANCE, ACCURACY AND
EFFORT IS WITH YOU.
Are you sure you wish to proceed (y/N)?


As you can see the N is a capital letter....
An article was suggesting that is already enabled by default in the latest systems, is it?

Any suggestion ?
Thanks

 

[Fishrrman]

I could be wrong, but I don't think there's any way to enable "TRIM" on a fusion drive, because a fusion drive isn't "an SSD".

Yes, an SSD is part of what comprises a fusion drive, but I don't think the command can be "focused upon" only the SSD portion of the fusion drive...

 

[rbart]

Of course, you need to activate TRIM on the fusion drive, it applies to the SSD portion.
But you shouldn't have to activate it, it's enabled by default (except if it's an homemade FD with a non apple SSD)

 

[katbel]

Should I activate TRIM on my MacBook Pro that is only SSD?

 

[rbart]

Of course, but if you have an apple SSD, it's activated by default ...

 

[fatso83]

Of course, but if you have an apple SSD, it's activated by default ...

That is what I assumed for far too long as well. The performance of my 5K 2017 iMac has been terrible for the last year, to the point of being unbearable and me looking at DIY how-tos on replacing the internal drive (scary stuff!). BUT as a last resort, I got to think about what a Fusion drive really is: a HDD and an SSD. And SSDs start performing really poorly in time, if TRIM is not enabled (which I remembered from my first SSD in 2009). Just running `git status` in a software repo took 12 seconds! So I gave it a shot:

- First thing: TRIM was not showing up in the System Information. This is not uncommon, if you google "FusionDrive TRIM". It seems some FDs show as two separate disks (especially older ones, 2012-2015) and others as a single bog-standard 7200 rpm HDD.
- Running `system_profiler SPSerialATADataType | grep TRIM` also showed nothing (as above).

I was at the time unaware of the internal `trimforce enable`command, so the first thing I came across was Trim Enabler, which I bought. This showed TRIM as not enabled! I enabled the switch, rebooted, and just a few minutes later I ran `git status` again. It executed immediately and `time git status` showed it taking less than half a second. Performance has since been fantastic!

So the moral of the story is: do not take anything for granted. Do your own research if disk performance grinds to a halt!