2011 mini Yosemite SSD slowdown

[santos.]

Hey guys,

Despite some issues getting my 2011 mini to run dual SSDs (https://forums.macrumors.com/threads/1725723/), everything was running fine. Hadn't run a speed test in a while so can't be positive it is directly related to Yosemite, but I recently realized that my primary/boot SSD (Samsung 840 250GB) is running at only 40MB/s W, 120MB/s R vs. my secondary SSD (Samsung 840 EVO 250GB) at 440MB/s W, 510MB/s R.

Hardware all seems fine, checks out in disk utility, no SMART errors or anything.

One thing possibly worth noting, the primary (problem) SSD was recently filled to capacity while backing up my new iPhone 6, but now that I have deleted some files it is back down to 50% capacity (roughly the same for the secondary).

Been messing with this all weekend, I even tried enabling TRIM by disabling the KEXT signing, but speeds were still the same.

Could this be related to upgrading to Yosemite? Temporarily filling the SSD to capacity? Anyone have any suggestions on how to remedy it?

 

[Weaselboy]

Could be all the recent writes to the drive have slowed it down, but one would think TRIM would restore that after a short time. Try this.

Enable TRIM then do a command-s boot to single user mode. Then change to the correct drive with cd.

cd /Volumes/volume_name

Then run this to TRIM free space.

fsck -fy

Then enter reboot and see if speeds improved.

 

[santos.]

Oh, does TRIM need some time to work? I only enabled it, tested speed, then disabled again when I thought it did nothing. Thanks for the reply will give it a try!

 

[Weaselboy]

Oh, does TRIM need some time to work? I only enabled it, tested speed, then disabled again when I thought it did nothing. Thanks for the reply will give it a try!

Yes it does.... and it also only works going forward as new data is written. It does not know how to clear that free space unless you tell it to like I mentioned.

 

[santos.]

Brilliant, thanks for the heads up, will try it as soon as I get home and report back.

 

[santos.]

Yes it does.... and it also only works going forward as new data is written. It does not know how to clear that free space unless you tell it to like I mentioned.

Yowza, you nailed it! Write speeds back up to advertised for the 840, 247 MB/s W, 470 MB/s R after following the above instructions. Looks like it was definitely maxing out the hard drive that caused it to drop so drastically. Fill those SSDs with care if you have not re-enabled TRIM on Yosemite people. Thanks Weaselboy, mad props

So I'm inclined to leave TRIM enabled now even though I'm not crazy about disabling kext-signing. Worth it though, right? Just need to be careful when installing drivers. I rarely change hardware so should be fine...

 

[NeilHD]

As a thought - have you upgraded to the fixed firmware for those drives?

 

[santos.]

2011 mini Yosemite SSD slowdown

I read that it was only available for the EVO even though it affected both, and since that one was fine for me I didn't bother. May have to look into it though. But enabling TRIM and running the above commands fixed my problem!