Resolved SSD slows way down on big file transfers

[Allistah]

I have a mid 2011 27" iMac 12,2.

I noticed that I have problems transferring large files on this OWC Mercury Electra 6G SSD (1TB). I used the stock cable that was in the machine that was attached to the stock hard drive.

Is the stock cable in this machine not capable of SATA 3 speeds?

What happens is that it is nice and fast when it starts and then it chokes down to almost a crawl. Then it speeds up again, then slows way down to almost nothing. Then it repeats this cycle but it seems to get worse the longer you let it go on. Here is what Activity Monitor shows when transferring a 50gb file on the drive. This happens in Mojave and Big Sur.

Is this the characteristic of a bad SATA cable?

Here is the graph of the data being transferred. You can see how it slows down to almost nothing most of the time:

UPDATE:
The SSD drive had over twice its lifetime in TBW written to it. This is the suspected reason why this was happening, but I would like to have tested this when the drive was new to see if this happened on day one or not.

Either way, I replaced it with a Samsung 860 EVO 1 TB drive and it completely fixed the problem. This is what transfers look like now:

 

[bkendig]

Just a hunch; do you have TRIM enabled for the drive? See https://www.cnet.com/how-to/installing-ssd-on-mac-trim-mistake/ for more info; also https://en.wikipedia.org/wiki/Trim_(computing) may be useful.

(I haven't heard of behavior like this from a bad SATA cable, no.)

 

[Allistah]

Yeah, that was the first thing I checked. Here is the dump of info for the drive below.

I also wanted to note that this happens in Mojave as well as Big Sur.

Does anyone have any idea what could be causing this problem then if its not a bad cable?

 

[Ruggy]

Any chance it's highly fragmented?
If you've got a big file to transfer and a large chunk of contiguous free space then it's easy, but if it's got to split it up and move it in little bits all over the place, then it will take a long time.

 

[BrianBaughn]

Just confirming…when you say "big file" transfers you mean a single, large file?

 

[Allistah]

Just confirming…when you say "big file" transfers you mean a single, large file?

Yeah.. A single big file. The problem starts anywhere after 3-6gb is transferred before the first slowdown shows up. It's really fast till that happens and then bogs way down. I wonder if there if any other ways I can troubleshoot thing?

 

[Allistah]

I don't use FAT. I use APFS.

 

[Allistah]

I downloaded DriveDx to see if there were any errors or anything with the drive. It reports everything is fine.

Really at a loss on why this happens in multiple OSs.

 

[nambuccaheadsau]

What patch did you use to bring the 2011 model up tom speed for Big Sur?

 

[Allistah]

What patch did you use to bring the 2011 model up tom speed for Big Sur?

The Barry micro-patcher. But I get the same problem in Big Sur, Mojave, and even High Sierra. It does exactly the same thing in all three. This is leading me to think it may be hardware somehow.

I have a SATA3 cable coming today to swap that out and see if that makes a difference. I was also wondering if I completely wiped the drive and all partitions and did a reinstall if that may have any difference but I'm not thinking so.

If anyone else has any other tips or suggestions, I'd love to hear it.

 

[mdgm]

How long have you had the SSD and how long ago did you last wipe it?

The Electra is OWC’s budget option, while the Extreme is their Pro option meant for more demanding use cases.

 

[Allistah]

The drive is only about 4 months old. The problem exhibits itself if I copy a 6 GB file, which is not a lot. The specs for the drive say it should be about to sustain writes up to 500 MB/sec. The issue I am seeing is that the copy drops down to about 10 MB/sec which is almost stopped. Then it picks back up and goes fast for a brief few seconds and then drops down to almost nothing.

 

[mdgm]

If I'm reading the output correctly to have written to a 1TB drive over 200TB in just four months, so you do appear to be a heavy user.

You've done writes that would take most users of that drive several years (maybe more than what many would ever do with that drive even if they keep it for several years) in just four months.

I think you chose the wrong drive for your use case.

From what I can gather the Electra is aimed at those who want fast speeds but on a budget and who may from time to time write a lot of data, but not 100s of GBs every day. For your kind of use case you want a Pro drive, whether that's the OWC Extreme, or one of the Samsung Pro's with a 10 year warranty or similar.

Wiping the drive may help but ultimately this SSD won't last you nearly as long as a professional grade SSD would.

 

[Allistah]

I booted off a USB key into recovery mode. I used Disk Utility to select the top level drive and erased it. It took a long time. So I did it again and timed it. Fully erasing the SSD that had 1 APFS partition and creating 1 APFS partition took 6 minutes, 4 seconds. The drive is 1 TB in size. Really feel that should only take a number of seconds to do since the drive is empty. I have a SATA 3 cable coming in the next couple hours, I’ll swap it out and see if this time changes when I do another full erase. Then I’ll do a fresh install of the OS and see if there is any difference.

But I am expecting the erase to be significantly faster than 6m 4s. That doesn’t sound right.

 

[mdgm]

Look at the specs of the drive: https://eshop.macsales.com/item/OWC/S4D7E6GT1.0/

You've written double what it is rated for. It's understandable you are having issues. The drive needs replacing.

 

[Allistah]

Pretty interesting as the machine is used for daily web browsing, email, etc. I’m surprised I’ve written that much data - twice the limit that is supposed to last 5 years, in only 4 months time. I could see if I was movung tons of big video files around constantly or something but I’m not. Can’t argue with the data. It appears that you’re right in that regard. But the drive is showing healthy in all areas.

I’ll swap out the cable when it gets delivered and see what happens. If that doesn’t change anything, I’ll be ordering another SSD for it. Will post back after I get the cable, install it, and test it again.

 

[mdgm]

If you're going to be writing 100s of GBs a day you probably should consider getting a TB3 NVMe drive. If the NVMe drive is bus powered you will need a TB3 dock to supply power to the drive.

iMac -> TB (1/2) cable to Apple TB3 to TB2 adapter (must be the Apple one as that is the only bi-directional adapter - note it doesn't transfer power) -> TB3 dock to TB3 NVMe drive.

Not only should that give you faster performance than a single internal SATA III (6Gbps) 2.5" SSD, if you use up the writes on the SSD it'll be much easier to replace.

You can get NVMe enclosures that you can put your own compatible NVMe SSD into if that's what you prefer. That way if the writes are all used up you don't have to replace the enclosure when getting a new SSD.

I think the OpenCore patcher for 3rd party GPUs has some fixes to improve NVMe support (not sure on this).

 

[mdgm]

Pretty interesting as the machine is used for daily web browsing, email, etc. I’m surprised I’ve written that much data - twice the limit that is supposed to last 5 years, in only 4 months time.

You probably want to figure out why it's writing so much data in that case so that it doesn't happen again with the next drive.

You have 16GB RAM according to your signature which should be more than sufficient for the usage you describe. However, still check if the memory (RAM) is swapping much to the disk. If it is, then increasing to 32GB RAM would be advisable. Insufficient memory is one of the ways to lead to writing way more than you should to a SSD.

 

[Allistah]

If you're going to be writing 100s of GBs a day you probably should consider getting a TB3 NVMe drive. If the NVMe drive is bus powered you will need a TB3 dock to supply power to the drive.

iMac -> TB (1/2) cable to Apple TB3 to TB2 adapter (must be the Apple one as that is the only bi-directional adapter - note it doesn't transfer power) -> TB3 dock to TB3 NVMe drive.

Not only should that give you faster performance than a single internal SATA III (6Gbps) 2.5" SSD, if you use up the writes on the SSD it'll be much easier to replace.

You can get NVMe enclosures that you can put your own compatible NVMe SSD into if that's what you prefer. That way if the writes are all used up you don't have to replace the enclosure when getting a new SSD.

I think the OpenCore patcher for 3rd party GPUs has some fixes to improve NVMe support (not sure on this).

I think I have one of these adapters and a cable. I’ve used the cable for target display mode in the past. This is the right adapter isn’t it?



Do you have any recommendations for a good enclosure? I have a Sabrent Rocket NVMe 2TB drive in my MBP and it’s been great

 

[OldMacs4Me]

FWIW have you opened up Activity Monitor when you are doing a transfer. One remote possibility is a corrupt Spotlight metadata file. That would hopefully show Spotlight registering high CPU usage. Unfortunately the cure is to delete the file and then wander away from the computer for however long it takes to rebuild the file. Be sure to have computer settings to never sleep and have it connected to AC power. This can take a looooong time.

Still I would check that before I swapped out an internal SSD.

Yes 2011 iMac should be SATA 3 for the Main HD. Optical bay is SATA 2. It sounds like there is a 3rd SATA port that can be either 3 or 2 depending on whether you ran the 2011 firmware update. Hopefully one of the various OS updates you did should have forced you to update firmware first.

Firmware Update Enables 6Gb/s in 2011 iMacs.

While iMac EFI Update 1.6 is is supposed to fix problems with Thunderbolt, it would also unlock the full 6Gb/s capabilities of internal drive bays.

eshop.macsales.com

 

[Allistah]

Installed the new SATA 3 cable. Erase still took 6m 4s. Installing Big Sur 11.1 now. Will see if it’s any different but I’m thinking the drive is just toast.

So if I use the TB2 port to a USB-C adapter, I’ll get better performance than the internal sata3 connection could get?! I have that adapter and cable, I guess I just need a USB-C external case and NVMe drive to go in it.

Does anyone have any recommendations for usb-c nvme cases?

Once I get BS installed and can test it again, I’ll report back.

 

[bkendig]

Any chance it's highly fragmented?
If you've got a big file to transfer and a large chunk of contiguous free space then it's easy, but if it's got to split it up and move it in little bits all over the place, then it will take a long time.

By the way - SSDs don't get fragmented. They don't have the concept of 'sequential blocks' or 'contiguous free space;' the mapping of solid-state memory locations to logical space can be changed instantly, and is adjusted constantly to wear the drive evenly. (Writing new data over and over to one specific location in solid-state memory will cause it to fail more quickly.)

Trying to defragment an SSD will only wear it out more quickly while doing literally zero for drive performance, so modern defragmenters will refuse to work on SSDs.

 

[mdgm]

So if I use the TB2 port to a USB-C adapter, I’ll get better performance than the internal sata3 connection could get?! I have that adapter and cable, I guess I just need a USB-C external case and NVMe drive to go in it.

That looks like the right adapter, yes and is what you would use to connect it to a TB3 Mac for use with TDM. You connect a TB (1/2) cable to the 2011 iMac and then connect the other end of the cable to that adapter. The Apple adapter is TB3 to TB2 (TB1 and TB2 use the same connector and it is backwards compatible). Whilst TB3 has the same connector as USB-C they are not the same. You can't plug a USB-C device into it. Be careful about marketing. Read the specs and manual to make sure the drive is actually TB3, not just using the same connector.

The adapter does not transfer power, so you either need a TB3 drive with an external power supply or a TB3 dock with a power supply to supply power to the drive.

The dock I got specifically stated that USB devices connected to the dock were only bootable on 2017 or newer Macs, so I needed to get a TB3 drive to boot my Mac. I don't know if using unsupported hacks like using OpenCore opens up more possibilities.

I think I read recently that on recent OS X Trim is automatically enabled for TB3 NVMe SSD drives.

You will get speeds faster than SATA III, but not a lot faster due to the TB1 interface on the 2011 iMac. However if you eventually move to a newer machine with TB3 and the drive still works you will get much better performance than SATA III.

I'm using OWC's new enclosure, but there's a thread indicating that doesn't work well with the Sabrent: https://forums.macrumors.com/thread...ues-help.2268762/?post=29410596#post-29410596

I only recently got the OWC enclosure and put an Aura P12 SSD inside, so I haven't been using it long enough to make a recommendation. Not the fastest TB3 SSD enclosure but the speeds the drive is capable of exceed TB1 speeds anyway. Using one with a 2011 Mac Mini and setting up one with a 21.5" 2011 iMac. Got it booting Mac OS X on both. Going to see if it will boot Windows despite what the specs say.

 

[Allistah]

I sort of feel dumb for buying that OCW drive. Feel like I got ripped off a bit. It was a little expensive. It’s life is about 100 TBW on a 1 TB.

I just looked up some Samsung drives - like the 860 Pro 1 TB. It has a life of about 1,200 TBW ($200). The 860 QVO 1 TB is 360 TBW ($141). The 860 EVO 1 TB is 600 TBW ($99)

I guess I should upgrade to 32gb of ram and replace the drive in this thing. Just not sure if it would be worth it to go the nvme route for better performance with an external drive on the TB2 port - I have the adapter and cable already. Just need a drive and case. If anyone has any suggestions, would love to hear them.

I also wanted to take a moment to thank those that took the time to reply and point out the real problem for me.

 

[Allistah]

That looks like the right adapter, yes and is what you would use to connect it to a TB3 Mac for use with TDM. You connect a TB (1/2) cable to the 2011 iMac and then connect the other end of the cable to that adapter. The Apple adapter is TB3 to TB2 (TB1 and TB2 use the same connector and it is backwards compatible). Whilst TB3 has the same connector as USB-C they are not the same. You can't plug a USB-C device into it. Be careful about marketing. Read the specs and manual to make sure the drive is actually TB3, not just using the same connector.

The adapter does not transfer power, so you either need a TB3 drive with an external power supply or a TB3 dock with a power supply to supply power to the drive.

The dock I got specifically stated that USB devices connected to the dock were only bootable on 2017 or newer Macs, so I needed to get a TB3 drive to boot my Mac. I don't know if using unsupported hacks like using OpenCore opens up more possibilities.

I think I read recently that on recent OS X Trim is automatically enabled for TB3 NVMe SSD drives.

You will get speeds faster than SATA III, but not a lot faster due to the TB1 interface on the 2011 iMac. However if you eventually move to a newer machine with TB3 and the drive still works you will get much better performance than SATA III.

I'm using OWC's new enclosure, but there's a thread indicating that doesn't work well with the Sabrent: https://forums.macrumors.com/thread...ues-help.2268762/?post=29410596#post-29410596

I only recently got the OWC enclosure and put an Aura P12 SSD inside, so I haven't been using it long enough to make a recommendation. Not the fastest TB3 SSD enclosure but the speeds the drive is capable of exceed TB1 speeds anyway. Using one with a 2011 Mac Mini and setting up one with a 21.5" 2011 iMac. Got it booting Mac OS X on both. Going to see if it will boot Windows despite what the specs say.

Thanks for all the info. I think I’m just going to get a new Sata3 drive for this thing and be done with it. I’m going to look and see about upgrading to 32gb of ram as well just to make sure I’m not swapping out to the drive. Need to price some memory I guess.