Resolved Slow SSD write speeds on older iMac

glenthompson

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Original poster
Apr 27, 2011
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Since my wife got a new iMac I took her old mid-2011 21.5" iMac that has a Samsung 840 Pro SSD installed. After erasing the drive, I installed a fresh copy of Sierra. After loading a few applications, I decided to run Blackmagic disk speed test. The read speeds were ok at 350-400 mbps. The write speeds however were abysmal at 20-25 mbps.

The drive has the latest firmware running.

Any ideas where the problem may be and how to fix it. Since it's an iMac, removing the drive for testing in other systems is not realistic.

I have the same drive in my late-2011 MBP and I get write speeds of 240 mbps and read of 480 mbps. Same firmware also.
 

Taz Mangus

macrumors 68040
Mar 10, 2011
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Since my wife got a new iMac I took her old mid-2011 21.5" iMac that has a Samsung 840 Pro SSD installed. After erasing the drive, I installed a fresh copy of Sierra. After loading a few applications, I decided to run Blackmagic disk speed test. The read speeds were ok at 350-400 mbps. The write speeds however were abysmal at 20-25 mbps.

The drive has the latest firmware running.

Any ideas where the problem may be and how to fix it. Since it's an iMac, removing the drive for testing in other systems is not realistic.

I have the same drive in my late-2011 MBP and I get write speeds of 240 mbps and read of 480 mbps. Same firmware also.
Check if Trim is enabled.
 

glenthompson

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Original poster
Apr 27, 2011
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Check if Trim is enabled.
It wasn't. I enabled it and ran the speed test again. Writes went closer to 100 mbps.
[doublepost=1498311370][/doublepost]
How old is your Black Magic software? A new version was released two weeks ago for top end SSDs. Update to version 3.1 if you are yet to do that. If that write speed is correct bad sign.
Version 3.1 - all software on the iMac was freshly downloaded.

Performance is getting better - writes are running about 150 and reads at 450.
 

Weaselboy

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Staff member
Jan 23, 2005
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It wasn't. I enabled it and ran the speed test again. Writes went closer to 100 mbps.
You are partway there. Now command-s boot to single user mode and enter the command below.

Code:
fsck -fy
You should see a notice at the end of the run that says "trimming unused blocks".... that TRIMS the free space on the drive and should restore your write speeds.

Try that and reboot then do a speedtest again. Let us know how it goes. :)
 

glenthompson

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Original poster
Apr 27, 2011
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You are partway there. Now command-s boot to single user mode and enter the command below.

Code:
fsck -fy
You should see a notice at the end of the run that says "trimming unused blocks".... that TRIMS the free space on the drive and should restore your write speeds.

Try that and reboot then do a speedtest again. Let us know how it goes. :)
That did the trick - writes are now 460 and reads 510. System is much more responsive.

Thanks for all the help.
 

Fishrrman

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Feb 20, 2009
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Taz wrote above:
"This is a good thread to pin/bookmark for future reference that shows that without Trim a SSD can really slow down over time."

This is also a good thread by which to rebut such nonsense.

Case in point:
Right now, as I post this, I'm booting and running my 2012 Mac Mini from a Crucial SSD sitting in a USB3/SATA docking station from plugable.com.

I first initialized and booted from the SSD in March 2014.
On March 13, 2014 it tested as new:
Reads: 431.7 mbps
Writes: 275.6 mbps

I retested it two minutes ago (3 years and 3 months of moderate/heavy usage):
Reads: 431.6 mbps
Writes: 274 mbps

Where's the big change?
 

Weaselboy

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Jan 23, 2005
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This is also a good thread by which to rebut such nonsense.
What nonsense? Are you suggesting the forum member in this thread is lying? You asked for evidence and it was provided. Everybody understands you have had no issues running without TRIM, but as this thread shows, your experience is not universal.
 
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Taz Mangus

macrumors 68040
Mar 10, 2011
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Taz wrote above:
"This is a good thread to pin/bookmark for future reference that shows that without Trim a SSD can really slow down over time."

This is also a good thread by which to rebut such nonsense.

Case in point:
Right now, as I post this, I'm booting and running my 2012 Mac Mini from a Crucial SSD sitting in a USB3/SATA docking station from plugable.com.

I first initialized and booted from the SSD in March 2014.
On March 13, 2014 it tested as new:
Reads: 431.7 mbps
Writes: 275.6 mbps

I retested it two minutes ago (3 years and 3 months of moderate/heavy usage):
Reads: 431.6 mbps
Writes: 274 mbps

Where's the big change?
You mean the OP who went from 20-25Mbs w/o Trim to 460Mbs with Trim enabled. Be careful what you call nonsense because it could be said the same of what you are posting.
[doublepost=1498402444][/doublepost]
That did the trick - writes are now 460 and reads 510. System is much more responsive.

Thanks for all the help.
Is Trim enabled on the 2011 MBP?
 

padams35

macrumors regular
Nov 10, 2016
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Where's the big change?
Crucial SSDs claim to have Active Garbage Collection to self perform TRIM-like cleanup on systems without TRIM supported/active. The only catch is the drives have to remain powered without ongoing data I/O operations for self cleanup to occur. If your experience is typical then I guess that feature really works.
 

Fishrrman

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Feb 20, 2009
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padams35 wrote:
"Crucial SSDs claim to have Active Garbage Collection to self perform TRIM-like cleanup on systems without TRIM supported/active. The only catch is the drives have to remain powered without ongoing data I/O operations for self cleanup to occur. If your experience is typical then I guess that feature really works."

Good observation.
That could be the case, I'm not sure.
The Mac Mini from which I posted the results above -does- rest "at idle" for certain hours of the day.

I don't know the answer.
All I know are the numbers I see when I run a speed test on the drive(s) in question.

I also have another boot SSD (this one a Sandisk Plus).
That one tests as does the Crucial -- that is, no speed degradations over time, even though it's connected via USB and TRIM cannot work.

If one has TRIM available, of course one should use it.
But if it's NOT available, one shouldn't be afraid of booting from a drive that doesn't support it.
I believe that in most cases the computer will wear out before the drive slows down significantly.

The overall experience will be dependent upon the DRIVE and not so much upon "the connection".

I've never used Samsung SSD's, perhaps they have an issue with TRIM with which I'm unfamiliar.
But Intel, Crucial, Sandisk -- no problems with them at all.
 

SaSaSushi

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Aug 8, 2007
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I've never used Samsung SSD's, perhaps they have an issue with TRIM with which I'm unfamiliar.
Never used them yet you have no problems whatsoever telling people in here that they have more problems than other makers.

Garbage collection is not a TRIM replacement and TRIM is beneficial to all SSDs no matter what sort of garbage collection is used. The OS sends the TRIM command to the SSD to identify what data can be ignored with garbage collection. There is no on-drive technology that can replace this.

No TRIM = increased write amplification, increased heat and potentially decreased performance and drive longevity.

The fact that you have apparently not perceived any issues of your own (yet) does not mean that other's experiences in here are any less valid.
 
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Fishrrman

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Feb 20, 2009
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SaSa wrote:
"The fact that you have apparently not perceived any issues of your own (yet) does not mean that other's experiences in here are any less valid."

Haha.

If the drives I have connected via USB3 -- which run as fast as they did when new, after years of usage -- have "issues", well...
... I hope those "issues" continue to build and build.

Keep 'em coming! (hearty laugh)

My 3+ year old Crucial boot SSD (in the USB3 dock) has been running since before 9am this morning (it's 9pm now), and is just barely warm to the touch.

Something tells me that two or three years from now, unless I replace the Mini before then, the same drive will still be running just fine.
 

SaSaSushi

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Aug 8, 2007
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Takamatsu, Japan
Something tells me that two or three years from now, unless I replace the Mini before then, the same drive will still be running just fine.
I hope it will be.

You've already agreed it is best to enable TRIM whenever possible so at least we share this opinion. Again, Garbage Collection was designed to enhance performance in non-TRIM situations and never as a replacement for it.

If you are going to be running MacOS off an external drive it is always best to enable TRIM. This is regardless of your drive's maker and especially true now (since OS X 10.10.4) that Apple officially allows it to be enabled for all third party drives and users can easily do so with a simple command line utility.

While its long-term effects are still a matter of controversy, write amplification is real and best avoided whenever possible. It can only lead to trouble.
 
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SaSaSushi

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Aug 8, 2007
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Takamatsu, Japan
If the drives I have connected via USB3 -- which run as fast as they did when new, after years of usage -- have "issues", well...
... I hope those "issues" continue to build and build.
Yeah well, some people might smoke cigarettes for a few years and not see any health effects but that doesn't mean I'd be advising anyone to do it, not even if I thought they could gain something else by doing so or somehow save a few bucks.

Meanwhile, sticking with that analogy we've already seen a few former heavy smokers in these forums die from COPD and magically be revived with a TRIM-enable and FSCK -Y bilateral lung transplant.
 
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glenthompson

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You mean the OP who went from 20-25Mbs w/o Trim to 460Mbs with Trim enabled. Be careful what you call nonsense because it could be said the same of what you are posting.
[doublepost=1498402444][/doublepost]

Is Trim enabled on the 2011 MBP?
Yes it is. The SSD in the iMac was erased and Sierra loaded fresh from a thumb drive. Before it was erased I thought trim was enabled but can't say for sure.
 

ur2funky

macrumors newbie
Aug 17, 2017
5
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Florida Keys
You are partway there. Now command-s boot to single user mode and enter the command below.

Code:
fsck -fy
You should see a notice at the end of the run that says "trimming unused blocks".... that TRIMS the free space on the drive and should restore your write speeds.

Try that and reboot then do a speedtest again. Let us know how it goes. :)
I just installed a couple new SSDs and I too am getting slow numbers. Is there a way I can use this trick for the other SSD drives in my Mac Pro that aren't the startup disk? Thanks!
 

ur2funky

macrumors newbie
Aug 17, 2017
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Florida Keys
I just installed a couple new SSDs and I too am getting slow numbers. Is there a way I can use this trick for the other SSD drives in my Mac Pro that aren't the startup disk? Thanks!
Update; I installed Sierra on a new EVO 1TB SDD drive, made it the Start up disk, enabled TRIM, and did the command-s trick from post #5. Still no change. Blackmagic speed test (ver. 3.1) is still showing 260MB write and 270MB read.
Any ideas to speed this up?
 

Weaselboy

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Jan 23, 2005
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Update; I installed Sierra on a new EVO 1TB SDD drive, made it the Start up disk, enabled TRIM, and did the command-s trick from post #5. Still no change. Blackmagic speed test (ver. 3.1) is still showing 260MB write and 270MB read.
Any ideas to speed this up?
How is the drive connected to the MP? It almost sounds like you are connected to an older SATA II connection.
 
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ur2funky

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Aug 17, 2017
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No... not if it is connected over SATA II.
Thanks for the help. I tried a Apricorn Velocity Solo x2 PCIe card ($85) to get at least one drive faster. My EVO SSD Write went from 256 to 488mb and Read went from 270 to 492mb.


I just ran across the OWC Accelsior S PCIe adapter for $50...

https://www.amazon.com/OWC-Computing-Accelsior-Adapter-Drives/dp/B00WUZPMHE/ref=pd_sbs_147_2?_encoding=UTF8&pd_rd_i=B00WUZPMHE&pd_rd_r=AMJF5C8Y7621649KB0MP&pd_rd_w=AsZ4q&pd_rd_wg=kLRU2&psc=1&refRID=AMJF5C8Y7621649KB0MP

I paid $85 for Velocity Solo x2... is it the same thing? Did I just lose $35? lol

https://www.amazon.com/Apricorn-Velocity-Extreme-Performance-VEL-SOLO-X2/dp/B0090IA3GY/ref=sr_1_1?s=electronics&ie=UTF8&qid=1503085177&sr=1-1&keywords=Apricorn+Velocity+Solo+x2
 
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p79alvarado

macrumors newbie
Aug 19, 2017
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You are partway there. Now command-s boot to single user mode and enter the command below.

Code:
fsck -fy
You should see a notice at the end of the run that says "trimming unused blocks".... that TRIMS the free space on the drive and should restore your write speeds.

Try that and reboot then do a speedtest again. Let us know how it goes. :)

i also have this issue. trim is enabled and i entered fsck -fy code in single user mode. is this just a slow mpb?


2010 mbp 15 inch
2.53 intel core
8 gb ddr3 ram
os sierra 10.12.6
samsung ssd 850 pro
254 write and 266 read (black magic 3.1)
93 gb of 256 gb used on ssd