Weird SSD behavior (sometimes slow, sometimes fast)

[Geron]

Hi,

i´ve just put a second SSD (Crucial M500 480GB) in my Mac Mini and it´s not
really working the way i want it to. When i´m moving files from my main drive (Samsung 840 Pro SSD) it´s as fast as i´m expecting it. But the other way around, when moving files from my Crucial drive to my Samsung drive, it´s much slower, nearly HDD speed. But that´s not all.

When i´m running the Blackmagic Disk Speed Test it show that the Crucial drive is working just fine, with about 400 MB/s in read mode and about 500 MB/s in write mode. So it can´t be the S-ATA cable or the drive itself.

I´ve already updated the firmware of the Crucial drive and been looking around the net half of the day for a solution. Only useful hint so far was from the Crucial support that i definitely should check the Disk Cache settings. But i haven´t found a way to do that yet. I did reset the NVRAM already though, but it didn´t help either :/

Any idea would be much appreciated

 

[Geron]

Oh, i´ve only just found out that my main drive is running extremely slow...
Around 100 MB/s write and only around 300 MB/s read speed. It´s not even that full either (around 60%). So that definitely shouldn´t be.

Any ideas?

 

[Geron]

Man, i only just found out about the TRIM feature on Mac. That´s not even funny...

Everything runs smooth as a cat now.

This information should be a sticky for Mac users lol!

 

[Geron]

One issues remains though. When i´m trying to move many files at (like 10,000 to 100.000) it begins
to stutter. It´s pretty bad when i´m doing it from the external 7200 RPM drive and occasionally bad when
i´m doing it from one SSD to another.

Sure, you´d expect this from the external drive, but the thing is, when i´m moving them to my main SSD it works just fine.

Any idea on that?