USB External SSD - Boot Drive - Slow down

[fenderbass146]

So I obtained a 2013 27" iMac about a year ago. It has a 7200 rpm drive which was just unacceptable to me at the time, but being a desktop, I figured I wouldn't mind just having a hard drive hanging off the back. So I used a USB 3.0 to sata cable and plugged in a Samsung Evo SSD and installed the OS and all my apps. It worked fine for at least a year, but in the last month or so it will bog down to the point I have to reboot after a few hours.

I checked ram usage and cpu, nothing is tasking those components, so it must be the storage issue. I assumed this wasn't still an issue, but apparently USB ssd drives don't support TRIM? Is that why it's going to slow. Anyone else has suggestions on how to fix this?

I'd be open to a Thunderbolt 1/2 cable to Sata but I can't seem to find one or they are $200+ dollars.

I'd love to put it internally, but from what I understand that's a bitch on these slim imac.

Anyone have a suggestion on how to prevent this slowdown, enable trim on usb ssd, or a cheap (sub $30) thunderbolt to sata adapter?

 

[Fishrrman]

I booted and ran a 2012 Mini for SIX YEARS using an external USB3 SSD.
TRIM was NEVER a problem.
That Mini still boots and runs from an external SSD on the back table.

Questions:
Do you use Time Machine?
If so, is your boot SSD clogged up with "local backups" and/or "local snapshots"?
How much free space is left on it?
What OS are you using?
Is the SSD formatted HFS+ or APFS?

 

[fenderbass146]

I do use time machine onto a NAS

I have 20 GB free and just freed up about 10 more GB of space so now I have 30 GB free on a 240 GB SSD

I'm running Catalina and am APFS
[automerge]1592403632[/automerge]

 

[mbosse]

TRIM can still be an issue - it simply depends on the type of SSD you use. I have both (second hand bought) Samsung and Intel SSDs which were extremely slow after long use without TRIM but returned to their original speed shortly after TRIM was enabled.

So there is no general rule which states that TRIM would be essential to maintain SSD speed, but it well could be.

Another question - is your Samsung SSD a 840 or an 840 Evo? Those had firmware issues with slowed them down tremendously after some use. Their most recent firmware updates addresses that, but a firmware update is IIRC not possible on USB.

Best,
Magnus