Samsung 850 Pro SSD slow write speed

Csmac · Jun 21, 2020

I have a MBP, mid 2012 and a Samsung 850 Pro that I bought about 4 years ago. It's always been fast with just over 500 MB/sec read and just under 500 MB/sec write. Now the speed is slowing down to about 350 MB/sec write and read can be between 400-500 MB/sec. I've checked the file system and done the fsck -fy. Trim in enabled. Empty space on the drive is 130 GB. Ideas? SMART doesn't report any issues. I'm at a loss to figure out why the slowdown. Speed checked with BlackMagic Speedtest and AJA System Test and they pretty much agree though BlackMagic shows a bit faster performance, but I think it is using Cache and AJA has cache disabled for the test.

jasongoldworthy · Jun 26, 2020

hi csmac

now im going to just throw this out there as I may be wrong but is it an age related problem ?

based on the drive being 4 years old it could be that data has been written back and forth by massive amounts and its slowing the drive down with age ?

(my guess here lol)

one more thing what size is the drive ?

is it a 256GB or a 512GB one ?

and could it be that as much as its saying there is 130gb free space is there a build up of unused files that's just filling the drive up ?

one more thing what OS version are you on ?

Csmac · Jun 26, 2020

Thanks for the reply jasongoldworthy.

I wondered about the age. I don't know how to tell if that is the cause. Sometimes it tests fine, but then drops off again. How to tell the difference between disk performance and system performance as either one could be part of the issue.

500GB drive. The trash is kept emptied so as far as I know there should be lots of space to use there.

MacOS Mojave 10.14.6.

I'm considering a fresh install just to be sure the system is as clean as possible, but of course that is not a trivial undertaking. I've chosen not to upgrade to Catalina as I have some 32 bit apps that are not upgradable.

jasongoldworthy · Jun 27, 2020

hi again Csmac

if you have a backup of your current files and folders

try a fresh Mojave install.

and Catalina isn't for everyone especially as some people do still use 32bit apps

do you know how many power on hours the drive has ?

Csmac · Jun 27, 2020

Just ran DriveDX and all looks good. Pwr On Hrs = 6127, no errors of any sort, wear leveling 61 or 98%, Lifetime Indicator 98%. As far as DriveDX goes it looks like the drive is just fine. Guess I'll have to bite the bullet and do a fresh install. I do have a bootable backup so that's not a problem. Ideally I'd like to do a fresh install of all the apps, but there's a ton of settings that would have to be made and that is the biggest pain. Guess I'll try a migrate first.

jasongoldworthy · Jun 27, 2020

hi again Csmac send us a screen shot of drivedx so I can take a look as if wear levelling is at 61% then that's likely the sign or as you said it could be 98% but best to let us take a look

hope I can help

Jason

Csmac · Jun 27, 2020

It's NOT 61%, just the number in one of the columns for that parameter. I suspect it is that it has done that operation 61 times.

jasongoldworthy · Jun 28, 2020

hi again

you are right its not the wear level count so I take that back,

it seems you have written 6.9tb to the drive in its life time but then again power on time isn't that high.

so it may be there is something slowing it down (bad files maybe)

have you checked the link speed in the about this Mac system profile sata/sata express ?

Csmac · Jun 28, 2020

Link speed & Negotiated speed is 6 Gbit. It's SATA III so that is correct.

I think we are forgetting that it was good and sometimes still checks good so it's not a setup issue as far as I can see. I'm getting more convinced that I just need to redo the system and that probably will be good for a number of things. I've not started from a clean system when upgrading OS versions for quite a while so it's due a cleanup anyway.

jasongoldworthy · Jun 29, 2020

hi again Csmac yeah I think your right best bet would be to try a reinstall if you can and its not a problem and see how you go ?

Csmac · Jun 30, 2020

jasongoldworthy,

Did the reinstall, it didn't offer me the option of a clean install, but automatically migrated everything. Oh, well, that was going to be my first try anyway.

Good news is that the drive seems to be performing much better. System seems more responsive also. Time will tell if it stays that way, but I'm hopeful.

Thanks for your input.

jasongoldworthy · Jul 1, 2020

hi Csmac that's good news that its running much better now,

hopefully this has solved the issue.

odd that it didn't offer you the option of a clean install but so far so good it seems

let us know how it goes