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Ric Ford

MacInTouch
It is going to depend on how you are doing the drag/drop. If you mount the old computer directly (e.g. with target disk mode or by mounting its storage in a USB enclosure) then you might have issues. If you want to transfer files that way, then you might prefer to use a mechanism other than drag-drop, probably involving a Terminal session...
As an illustration of what can go wrong, I once selected my home directory, did Get Info, and told the Finder to set my account owner and permissions for all sub-folders. That was a giant mistake, because, among those hundreds of thousands of files within my user directory are many special files that need special owners and permissions, e.g, in ~/Library/, in special Apple areas, etc. There is no "undo" for that operation in the Finder, and I know of no way to automatically sort out correct owners/permissions (Repair Permissions doesn't do anything like that).

A separate issue is various caches, which might get quite confused by owner/UID changes, etc.
 


Just upgraded a late 2009 27-inch iMac, since it was about to fall off Apple's list of fully supported hardware. Wonderful machine, that; sad to see it dropped.

Since I wanted to use macOS 10.14 and beyond, I needed at least a Metal-plated GPU. But I also decided I should opt for Retina display, and got the cheapest one I could locate, the first Retina 27" iMac of late 2014. Good choice.

The new machine seems peppier in every thing I normally do, scrolling, switching tabs, photo editing, audio editing, you name it. Note it has double the DRAM (to 24GB), a 128GB SSD, and a much more powerful GPU to handle the extra pixels.

Sorry, I do not attempt to quantify my experiences here. Seat-of-pants is sufficient for my purpose and since I tend to run on cheaper hardware than most here, with Core i5's and fusion drives, comparisons would not reveal much.

I am thrilled with the late 2014 iMac under Mojave beta. It was one large, well spent on eBay. Thank you, Apple, for pushing me to upgrade. I hope my seller bought some nice new expensive Apple hardware from you through Ric's MacInTouch site!
 


John Siracusa's OS X 10.9 review for Ars Technica explained changes in memory management as being pretty much the opposite approach, so this doesn't seem to explain OS X 10.9's need for SSD vs. hard drive storage. I think there's a different explanation for the sudden drop in performance at that point with hard drives, but I don't have an explanation handy.
I totally stand corrected. My guess is the issue is with cache file creation/deletion (which takes a crazy amount of time even on SSDs when a major version upgrade is in swing).
 


Considering our local retailer has an attractive special on the Samsung T5's at the moment, I think I might grab three 250-gigs for the 21.5"s and a 500-gig for the 27", and run the iMacs off them, using the internal drives for back-ups and rarely accessed files.
I'm going to give this a try, as well, to speed up my 2017 21.5" iMac with a 1TB Fusion. Any other tips or suggestions for using the T5 as a boot drive? Is TRIM an issue on the T5? I'm considering making the file transfer to the T5 using SuperDuper.
 


Could you accomplish the same thing by booting normally, then using EtreCheck to generate a report showing which LaunchAgents and LaunchDaemons are running, and then tracking down the old/obsolete ones at that point? ...
Absolutely. I prefer manual checking, because I want to minimize the chance of a client having issues after I leave their site. For DIY, EtreCheck is a good choice.
 


Ric Ford

MacInTouch
I totally stand corrected. My guess is the issue is with cache file creation/deletion (which takes a crazy amount of time even on SSDs when a major version upgrade is in swing).
I've been doing more digging, and this is what I've found so far:
comp.sys.mac.system said:
Why Mavericks is slow or fast or needs an SSD

10.6: This is often cited as the most elegant and most efficient OS X to date. It's generally very fast and it handles heavy duty tasks well. There's the occasional case where it does badly - runaway RAM hogs. A process demanding a very large amount of RAM was able to steal almost all of it away from everything else. Idle processes would entirely "swap out" to disk and deactivate. Windows buffers would even page out so that dragging a window caused it to shimmer as it paged back in. All of this was good if a process needed the RAM momentarily to finish a task but it also meant that a runaway RAM hog required a power cycle.

10.7/10.8 : A solution is created for the runaway RAM hog: As of 10.7, no process is allowed to consume more than some fraction of total RAM and idle processes are no longer swapped out. This backfires horribly. Processes that need large amounts of temporary RAM are forced to swap within their tiny allotment. All of this paging monopolizes the filesystem so that the new features needing continuous filesystem access, like Auto Save, Auto Restore, Versions, and Mobile Backup, bring all Apple applications to a halt. Old HFS+ isn't able to handle this. A process that needs temporary RAM takes 10x to 100x longer to finish than it did under 10.6, and new Apple apps are crippled the whole time.

10.9 : The broken VM tuning from 10.7 is fixed and augmented with compression. VM compression consumes some RAM of its own but it generally outperforms 10.6 virtual memory. Apple also adds a fix for processes that monopolize the filesystem: Each process is throttled. You can see this in 'fs_usage' as log entry "THROTTLED." Again, a new fix backfires horribly. Processes that shouldn't be throttled and don't need to be throttled still get throttled. In my case, applications were getting just 300KB/sec of filesystem throughput; a 97% loss compared to 10.8 and worse again compared to 10.6. People who install an SSD notice a vast improvement while people who already have an SSD notice that it still seems slow. What's going on? Check these system parameters:

debug.lowpri_throttle_max_iosize: 131072
debug.lowpri_throttle_tier1_window_msecs: 25
debug.lowpri_throttle_tier2_window_msecs: 100
debug.lowpri_throttle_tier3_window_msecs: 500
debug.lowpri_throttle_tier1_io_period_msecs: 15
debug.lowpri_throttle_tier2_io_period_msecs: 50
debug.lowpri_throttle_tier3_io_period_msecs: 200
debug.lowpri_throttle_tier1_io_period_ssd_msecs: 5
debug.lowpri_throttle_tier2_io_period_ssd_msecs: 15
debug.lowpri_throttle_tier3_io_period_ssd_msecs: 25
debug.lowpri_throttle_enabled: 1


These parameters idle processes to limit their filesystem use. Apple has provided a less aggressive throttle if an SSD is being used, which is why an SSD helps in cases where spinning rust should suffice.

Fire up your favorite disk intensive task and wait for the throughput to fall to nearly nothing. Now run:

sudo sysctl -w debug.lowpri_throttle_enabled=0

Boom! Throughput is back! Now all the Apple apps are beachballing again, but at least the computer isn't sitting idle any more.

All of this throttling is a very poor workaround to what has been needed for many years: A new filesystem. HFS+ is too old, too slow, has too many caching bugs, too many journaling bugs, and produces complex filesystems that corrupt easily. As of Yosemite, there's still the same old filesystem in place crippling the OS. Your new $6000 Mac Pro is going to sit idle every time heavy disk I/O is demanded.

#performance #ssdvshdd #mavericks #compresssion #slowdown #memorymanagement #throttling​
 


My 2017 iMac with 3TB fusion drive is quite snappy in ordinary use. As was reported from the beginning, tasks that force storage access outside the SSD portion of the drive, like disk imaging, slow down to spinning drive speeds. The 45-minute combo update this week might have involved a lot of that. Dramatically faster with modern macOS than my late 2009 iMac and its 1TB spinning drive!
I have a 2TB version with the 128-gig SSD. Assuming that all of the major apps and the OS fit in the 128-gig SSD, the speed of the iMac most of the time should just as fast as a pure SSD. I find my iMac to be quite speedy relative to my older iMacs. But I do not do photography or video, so my test is really using a CAD program.
 



And, in fact, I know one office where they do the reverse: they plugged in external Thunderbolt SSDs, and boot off those, while using the internal drives for storage. Works much faster and has the added benefit that it lets the user take their boot drive with them - it’s actually more servicable than the standard way of doing things. Apple was considering things like that way back when they were experimenting with using an iPod to store your user profile (talk about slow access).
I'm curious what product they're using and whether or not they've had any trouble with it (e.g. disconnections).
Just to add another data point: My wife has two near-identical 27" mid-2011 iMacs; one in her home office, and one at our vacation property. These machines only have USB2 and Thunderbolt 1 ports. When we migrated from Snow Leopard to Sierra over a year ago, I knew running the new OS from the internal spinning drive would be unacceptably slow and wasn't willing to risk damaging two machines by attempting to install SSDs in them.

I bought a Lacie Thunderbolt/USB3 Rugged drive and installed a 1TB Samsung 850 EVO SSD in it. Both machines are setup to boot from the external SSD, and the original internal spinning drives are used for CCC and Time Machine backups. My wife simply shuts down the machine and takes the external SSD when she changes location.

So far, we have experienced no problems doing this, except a little funkiness following OS updates (machine reboots into Recovery partition), and the inability to use the mouse during startups (known issue). On the upside, I only have one "machine" to update, initial OS/app installation was done using a third machine, and my wife doesn't have to worry about transferring needed files when she changes location. Finally, the SSD is partitioned and the boot partition is encrypted.
 


It is going to depend on how you are doing the drag/drop. If you mount the old computer directly (e.g. with target disk mode or by mounting its storage in a USB enclosure) then you might have issues. If you want to transfer files that way, then you might prefer to use a mechanism other than drag-drop, probably involving a Terminal session and either "cp" or "rsync" with an appropriate set of options.
You might want to avoid copying the ~/Library folder, in case it has content (e.g. preferences and caches) that are incompatible with the newer software on the new computer, but that's only real problem I can think of. If you omit it, you'll lose application preferences and possibly some customization (e.g. if you have content in ~/Library/Sounds or ~/Library/Fonts), but you shouldn't break anything. I don't remember if I copied mine or not - I think I did, but it's been a while since the last time I did this.
I migrate much the same way and find it offers finer control (than migration tools) over what moves or does not move to the new machine. For the rsync I use BackupList+ (exceptional utility) and I especially copy the ~/Library/Preferences and ~/Library/Application Support folders - or most of the stuff within them. For me, that is where all the good stuff lives (for example, Adobe>CameraRaw settings, where hundreds of hours of my life are found).

I do not remember when it happened some years ago, but when Apple starting making the user library invisible, I was mystified to understand why. I still am.

chflags nohidden /Users/xxx/Library

is your friend (where xxx is your user name).
 


I do not remember when it happened some years ago, but when Apple starting making the user library invisible, I was mystified to understand why. I still am.
chflags nohidden /Users/xxx/Library is your friend (where xxx is your user name).
The user Library folder can be made visible without a terminal command. While viewing the user folder in Finder, select Show View Options from the View menu. At the bottom of that panel is a check box labeled Show Library Folder.
 


I bought a Lacie Thunderbolt/USB3 Rugged drive and installed a 1TB Samsung 850 EVO SSD in it. Both machines are setup to boot from the external SSD, and the original internal spinning drives are used for CCC and Time Machine backups. So far, we have experienced no problems doing this, except a little funkiness following OS updates (machine reboots into Recovery partition)
I followed this approach with my setup, using a 2012 Mac Mini, OWC Thuderbay 4, and Crucial MX200 SSD. I also have a monitor running at 2560x1440 via DisplayPort which is daisy-chained through the Thunderbay. No problems at all for the last 3 years. In fact, I was able to do an in-place hardware upgrade from a 2011 Mac Mini to a 2012 by simply powering down, swapping Mac Minis, and powering back up.

In the past, updates to Mac OS would reboot to the internal drive, which I keep updated as a bootable clone. But the last several updates to High Sierra have correctly booted from the external SSD.
 


Ric Ford

MacInTouch
I'm not sure if this has been linked here before, but AnandTech has a good article about Apple's Fusion Drive, written before Anand Lal Shimpi joined Apple:
Anand Lal Shimpi said:
A Month with Apple's Fusion Drive
... It seems that Fusion Drive is really made for the user who doesn't necessarily have a ton of applications/data, but does have a reasonable sized media collection. For that user, Fusion Drive should be a reasonable approximation of a well managed SSD/hard disk drive setup with your big media files going to the hard disk drive and everything that you launch frequently living on the SSD. I’m always going to ask for a larger cache, but I do believe that 128GB is a good size for most client workloads and usage models today. For me in particular I’d probably need a 256GB cache for Fusion Drive to win me over, but I understand that I’m not necessarily the target market here.

The real question is whether or not it’s worth it. I’m personally a much bigger fan of going all solid state and manually segmenting your large media files onto hard disk drive arrays, but perhaps that’s me being set in my ways (or just me being right, not sure which one). Fusion Drive doesn’t do anything to mitigate the likelihood that a hard drive will likely fail sooner than a good SSD, whereas if you go with an internal SSD and external (Thunderbolt or USB 3.0) hard disk drive RAID array you can control your destiny a bit better. Unfortunately, in situations where Fusion Drive is a choice, you don’t often have that flexibility. ...
 



It occurs to me that a hybrid drive probably performs about the same as a fusion drive, which might be useful for experimenting, etc.
I have used several of the hybrid drives. Initially, the hybrid drives had a small amount of flash memory with the 7200-rpm hard disk. The next hybrid disk that I used had more flash memory, but the spinning drive was 5200 or so rpm. Yes, the hybrid drive is faster, and the hybrid drive drives that I purchased did not cost significantly more than a good quality spinning hard disk. But the flash memory was not big enough to make much of a difference. The major difference was boot times, rather than for workflow activity. I suspect the flash memory made the 5200-rpm disk behave more like a plain 7200-rpm hard disk. (Note that the information in the flash memory is a copy of what is on the spinning hard disk platters.)
 


Not in my Finder's View options (macOS 10.13.6).
I see there was a typo in my original posting. Rather than the user folder, it's the user's home folder that needs to be shown in Finder. That checkbox doesn't appear unless a home folder is being viewed, and it works for me on macOS 10.13.6.
 



On my new iMac 27" (model 18,3; 3.5Ghz i5) running up-to-date Sierra 10.12.6, the brightness on the built in screen keeps creeping up on me. This is not just a visual trick, the slider in the "Displays" system preference pane has moved up also. "Automatically adjust brightness" is not activated.

It seems random, does not happen after every restart. No one else has access to the computer, so it is not being done manually. There is an LG 32" FHD monitor attached via Thunderbolt to VGA adaptor (as the Thunderbolt to HDMI is too flakey), and the brightness on this monitor is unaffected. Anybody else ever seen this?
 


Ric Ford

MacInTouch
On my new iMac 27" (model 18,3; 3.5Ghz i5) running up-to-date Sierra 10.12.6, the brightness on the built in screen keeps creeping up on me. This is not just a visual trick, the slider in the "Displays" system preference pane has moved up also....
Is there a brightness button on the keyboard that you might be hitting accidentally?
 


Thanks for your reply Ric. Standard Apple Magic Keyboard with Numeric Keypad. Function keys are set to standard, which requires both the F2 and Fn keys to be depressed simultaneously to increase the screen brightness. I guess this might happen if there were objects resting on the keyboard (sheets of paper sometimes do end up in contact with it), but it seems unlikely that it would happen repeatedly. I will keep an eye out for a correlation though.
 


My old Mac Mini is slowly dying. I have good backups of everything, prepared for the day it finally gives up the ghost (which, after what’s been happening, may be fairly soon).

So, I’ve been looking at an iMac to replace it. I’ve always been hesitant about all-in-ones, but at this point I have little faith in a new Mini being what I’d want. I see most of the more recent (guess, that’s like 3 years old now?) models as a downgrade from previous models. Sadly this seems to be a theme with a lot of the Apple product line that isn’t named iPhone or iPad (though some would even argue that). I’m looking at the higher end 21.5” iMac for the better graphics card in it. I don’t need a killer graphics card, but something a bit better than an integrated graphics would be nice.

While I definitely don’t need the 27” size screen, the fact you can actually access the RAM in those fairly easy has made me glance at them several times.

Then, of course, there’s the question, are the iMac’s going to see any kind of spec bump/redesign/whatever this year or not? I’d hate to get something in the next couple of weeks only to see something better come out just a couple months later for the same price. The rumor mill seems to be quieter when it comes to the iMac. Most of the rumors seem to be swirling about iPad Pros and iPhones. Is it reasonable to expect there will be an upgrade to the iMac (not pro) line this year, or might that still be another year off? Just wondering if anyone has heard anything, or if anyone has any advice on the iMac in general. Thanks!
 


Ric Ford

MacInTouch
My old Mac Mini is slowly dying. I have good backups of everything, prepared for the day it finally gives up the ghost (which, after what’s been happening, may be fairly soon). So, I’ve been looking at an iMac to replace it. ... Is it reasonable to expect there will be an upgrade to the iMac (not pro) line this year, or might that still be another year off? Just wondering if anyone has heard anything, or if anyone has any advice on the iMac in general. Thanks!
I've been discussing these same issues with a friend in email, by chance, so here are a few items from that discussion for what they're worth:
  • We think current Mac Mini prices are outrageously high (and the moribund Mini doesn't even have Thunderbolt 3).
  • I suspect, but haven't tested, that a 21" iMac 4K may feel faster than a 27" iMac 5K, due to the heavy overhead of 5K graphics.
  • You can always attach any monitor you want to the 21" iMac, via Thunderbolt 3, which is a big benefit for this computer.
  • You're right about lack of memory upgradability for 21", which I find unconscionable and infuriating on Apple's part.
  • A hard drive is a non-starter in terms of performance. A 1TB fusion drive may not be much better. A 2|3TB fusion drive may be OK, in order to save money on Apple's exhorbitant SSD prices. An external Thunderbolt 3 SSD may be an alternative, and even a USB3 SSD should be usable.
  • Neither of us has any idea if Apple will update its non-"pro" iMacs this year, but I'm concerned that Apple may not want to 1) invest in the update 2) compete too much with the slow-selling "pro" model and the MacBook Pro line.
  • If Apple does update the non-Pro models this year, they should see a nice performance boost (as with the 2018 MacBook Pros) but may also have more problems (e.g. with T2 chips).
  • I'm not holding my breath for a new, decent Mac Mini this year, but who knows? It's long past time for one.
  • I'm looking at a $750 Dell laptop that has almost everything one would need... (except macOS and a super-thin/super-light body). Apple isn't even in the same league for price/performance/flexibility with its offerings.
 


Ric Ford

MacInTouch
Here's some interesting information about an iMac 5K performance issue:
Mac Performance Guide said:
2017 iMac 5K: Flash Drive (SSD)
Big surprise! The late 2015 iMac 5K SSD outperforms the 2017 iMac 5K for the critically important transfer sizes up to 1MB, particularly for writes, where the 2017 model lags badly. Many if not most programs do not read or write data in chunks larger than 1MB, so these results mean that the 2017 iMac 5K might actually perform less well in I/O intensive situations.

Reading a mix of 217000 files of varying sizes (html files and JPEG) shows that the performance is slightly in favor of the 2015 iMac 5K with a mix of text files and large JPEGs, but about 40% faster on the 2015 iMac 5K with small files (html files of a few kilobytes). This argues that things like file copying, or searching/grepping, git, etc will be faster on the 2015 model. Thus the 2017 iMac 5K is substantially slower for everyday tasks that involve intensive I/O with smaller reads, in spite of the 40% greater speed for large reads. This is a disappointing result in light of the speed gains in CPU and GPU speed.
 


My old Mac Mini is slowly dying. ...
... Just wondering if anyone has heard anything, or if anyone has any advice on the iMac in general. Thanks!
I have been using Macs for way too long, and always purchased towers and laptops. When it was time to replace my 2008 Mac Pro about 3 years ago, I decided to give a 27" iMac 5K a try. I have been very happy overall.

I do miss opening it up to add or replace hard drives, but SSD's on USB are very fast. I was able to install Windows 10 on a external Thunderbolt SSD, and that has worked very well.

Besides the usual computing stuff I use Lightroom and Photoshop, and when I have free time I fly [X-Plane] and, on Windows, Microsoft Flight simulator.

I think for the price/performance, it was a good purchase. I have the 2TB fusion drive, and my only complaint is that installing Boot Camp would only use the spinning disk. But the Thunderbolt SSD has solved that problem.
 



....
So, I’ve been looking at an iMac to replace it. I’ve always been hesitant about all-in-ones, but at this point I have little faith in a new Mini being what I’d want...
Then, of course, there’s the question, are the iMac’s going to see any kind of spec bump/redesign/whatever this year or not? I’d hate to get something in the next couple of weeks only to see something better come out just a couple months later for the same price....
There have been some recent rumors of a Mac Mini update coming later this year. If you go to the MacRumors buyer guide page, it is the most embarrassing system there for Apple - 1383 days... by October that will be in the 1400's creeping ever closer to the 1500's. It has blown past where the Mac Pro was when they "re-jiggered" the pricing to reset the clock.

If Apple keeps up their "can't walk and chew gum at the same time" Mac development characteristic, then a choice between Mini or iMac update would probably be Mini.

I wouldn't expect the Mini or an iMac until after Mojave ships (with its ability to finally deal with APFS "Fusion" drives). It probably won't be weeks. More likely something in late Oct. to mid November (end of December if they have a supply/testing hiccup).

If AMD has a Polaris speed bump in Q4 to match up to Intel's incremental move on CPUs (6 cores and security fixes), then perhaps Apple will walk and chew gum at the same time in their desktop line-up (both Mini and iMac update). If Apple doesn't have both in volume (at a discount), then the iMac probably coasts into 2019 'as is'.
 


Well I ended up pulling the trigger on a new iMac 27-inch. Like others, I fear any new ones will end up killing the last user-serviceable part on it (upgrading the RAM... the one thing I want to do and not pay the insane Apple RAM BTO prices).

While I thought about waiting to see if they updated the Mini (or killed it off), I just felt, looking at the current crop of them, it would be yet another perfectly sealed box (for our own protection, of course) and you’d have to spend the big BTO bucks to actually get a decent amount of RAM or hard drive in it.

Now I just have to wait for it to come. Last night FedEx said it would be arriving today. Today they seem to have said “whoops, we meant tomorrow”. I thought it was only passengers traveling through NJ that got massively delayed... guess it’s packages, too.
 


My new iMac 5K Retina 27" 2017 model, running up-to-date Sierra 10.12.6, continues to randomly increase the brightness of the screen by itself, as reported back in July.

At Ric's suggestion I have been vigilant about making sure nothing is left in contact with the keyboard to eliminate the possibility of the F2 brightness and Fn keys being activated simultaneously by accident.

It only ever gets brighter, never less bright. Automatically Adjust Brightness is not selected. As previously, the LG 32" FG monitor connected by Thunderbolt is not affected, just the built-in monitor.

I guess it is a software issue rather than hardware related, as the slider in the system preference panel has moved up, but I have no idea what could be causing it.
 


My new iMac 5K Retina 27" 2017 model, running up-to-date Sierra 10.12.6, continues to randomly increase the brightness of the screen by itself, as reported back in July.

At Ric's suggestion I have been vigilant about making sure nothing is left in contact with the keyboard to eliminate the possibility of the F2 brightness and Fn keys being activated simultaneously by accident.

It only ever gets brighter, never less bright. Automatically Adjust Brightness is not selected. As previously, the LG 32" FG monitor connected by Thunderbolt is not affected, just the built-in monitor.

I guess it is a software issue rather than hardware related, as the slider in the system preference panel has moved up, but I have no idea what could be causing it.
Interesting, this was a known issue with the iMac Pro (the brightness would always reset to two notches below full brightness after restart), and it was fixed in the latest OS 10.13.6 High Sierra update. Whether there was a firmware update bundled in with that I don't know, but a lot of people suspected it was related to the T2 chip. Either way, this is the first I've heard about it on a regular iMac.
 


Interesting, this was a known issue with the iMac Pro (the brightness would always reset to two notches below full brightness after restart.
Two notches below full brightness is the same symptom on my machine. However, it is not after every restart - maybe once a week.

Quite noticeable when it happens, as I have my screen quite dimly set at about two-thirds full brightness.
 


My new iMac 5K Retina 27" 2017 model, running up-to-date Sierra 10.12.6, continues to randomly increase the brightness of the screen by itself.
Same here on a 2017 iMac 27-inch. My manual brightness reductions wouldn't remain set, but the unwanted behavior is gone in macOS 10.13.6. Thank you, Apple, for fixing this.
 


I have a 2017 iMac running Mojave, although this issue first appeared under High Sierra.

My internet speed using Ethernet is slower than using WiFi. After extensive research and analysis I've isolated the problem to the Ethernet interface being throttled with a Link Speed of 100Mbit/s. This information is displayed running Network Utility.

I've tried multiple cables, and that is not the problem. I can connect a MacBook Pro to the same cable, and it shows a Link Speed of 1Gbit/s.

I've tried running the iMac in Safe Mode and with a new user account, but neither solves the problem.

I've contacted Apple Support multiple times and they suggested the following:
  • Reset NVRAM or PRAM
  • Reset SMC
  • Reinstall macOS from macOS Recovery
None of these resolved the problem.

Finally I used System Preferences > Network > Ethernet >Advanced > Hardware to manually configure the network, but when I tried to increase the speed I got an error message.

Next step is to take the iMac to the Genius Bar, as I suspect it is a hardware issue with the Ethernet port that is causing the problem. However, I thought I'd post here and see if anyone might have any additional suggestions to resolve this issue if, in fact, it is software-related.
 


Ric Ford

MacInTouch
We're looking for a good home for a free Mac - 2010/2011 vintage with optical drive and a dead hard drive - in Sydney. If you're interested (especially if you're near Kingsgrove), let me know.
 


I have a 2017 iMac running Mojave, although this issue first appeared under High Sierra.

My internet speed using Ethernet is slower than using WiFi. After extensive research and analysis I've isolated the problem to the Ethernet interface being throttled with a Link Speed of 100Mbit/s. This information is displayed running Network Utility.

I've tried multiple cables, and that is not the problem. I can connect a MacBook Pro to the same cable, and it shows a Link Speed of 1Gbit/s.

I've tried running the iMac in Safe Mode and with a new user account, but neither solves the problem.

I've contacted Apple Support multiple times and they suggested the following:
  • Reset NVRAM or PRAM
  • Reset SMC
  • Reinstall macOS from macOS Recovery
None of these resolved the problem.

Finally I used System Preferences > Network > Ethernet >Advanced > Hardware to manually configure the network, but when I tried to increase the speed I got an error message.

Next step is to take the iMac to the Genius Bar, as I suspect it is a hardware issue with the Ethernet port that is causing the problem. However, I thought I'd post here and see if anyone might have any additional suggestions to resolve this issue if, in fact, it is software-related.
Do you have the text of the error message from your attempt to change the port link speed to 1 Gbit/s?

Also, you don't say what your uplink is (switch, router, &c.) and what the specs on its link speed(s) are. Some older hubs have problems negotiating link speeds.

If you've tried it with different switches, though, you're right to call Apple Support and make an appointment at a Genius Bar. Hope you still have AppleCare.
 


Do you have the text of the error message from your attempt to change the port link speed to 1 Gbit/s?
Also, you don't say what your uplink is (switch, router, &c.) and what the specs on its link speed(s) are. Some older hubs have problems negotiating link speeds.
If you've tried it with different switches, though, you're right to call Apple Support and make an appointment at a Genius Bar. Hope you still have AppleCare.
Network > Advanced > Hardware automatically sets itself to 100baseT. When I change this manually to 1000baseT, I get the message "Cable Unplugged. Either the cable for Ethernet is not plugged in or the device at the other end is not responding."

The Cat5e cable is connected directly to my router. If I plug the same cable into the MacBook Pro, I get 1Gbit/s and 1000baseT, so I don't think it's the cable or the router. Xfinity gives me >250 Mbps on the MacBook Pro.

Since I used to get similar speeds on the iMac, I'm guessing it's either software (now doubtful) or a problem with the Ethernet port itself. I'm not an expert, but perhaps one of the eight wires is not making proper contact between the cable and the port.

Anyhow, yes it's still under AppleCare, and I've got an appointment at the Genius Bar on Monday.
 


Network > Advanced > Hardware automatically sets itself to 100baseT. When I change this manually to 1000baseT, I get the message "Cable Unplugged. Either the cable for Ethernet is not plugged in or the device at the other end is not responding."

The Cat5e cable is connected directly to my router. If I plug the same cable into the MacBook Pro, I get 1Gbit/s and 1000baseT, so I don't think it's the cable or the router. Xfinity gives me >250 Mbps on the MacBook Pro.

Since I used to get similar speeds on the iMac, I'm guessing it's either software (now doubtful) or a problem with the Ethernet port itself. I'm not an expert, but perhaps one of the eight wires is not making proper contact between the cable and the port.

Anyhow, yes it's still under AppleCare, and I've got an appointment at the Genius Bar on Monday.
Just one more question: did you plug the patch cord into the same port on the router as you were using for the iMac? Sometimes individual ports, or groups of ports, fail. It sounds, though, as if your testing has been extremely thorough, so I'm certain you've thought of that.

Assuming it's the Ethernet port on the iMac, I hope you have a good backup, since fixing that probably requires a main logic board replacement, and Apple never guarantees that anything on internal storage will survive that.
 


An alternative to the pain of logic board replacement is an external USB to Ethernet adapter such as those by Anker. I have had good results with both USB 3 and USB C versions, although the USB C connector is more fragile. I prefer an aluminum body over plastic for heat dissipation.

Anker USB 3.0 Unibody Portable Aluminum Gigabit Ethernet Adapter Supporting 10/100/1000 Mbps Ethernet for Macbook, Mac Pro/mini, iMac, XPS, Surface Pro, Notebook PC and More

Anker USB-C Unibody Aluminum Portable 1-Gigabit Ethernet Port Network Adapter, 10/100 / 1000 Mbps Compatible, for MacBook Pro 2016, XPS, ChromeBook Pixel and More
 


I would double check the port itself and see if one of the pins isn't up in alignment vs. the others. I've seen that happen and, while lower speeds accept that, gigabit won't.

Try booting into recovery mode and checking the network speed there - that is a minimal OS, and nothing you've done should affect that configuration. That should let you check the auto-negotiation results pretty easily.

And I also agree that the USB or Thunderbolt adapters are a better option than a Genius Bar visit, which will cost many times more if there is a repair needed. Maybe let them do the diagnostics to be sure it is a hardware issue, but then refuse the repair, and buy the adapter for $20.
 


I have a 2017 iMac running Mojave, although this issue first appeared under High Sierra.

My internet speed using Ethernet is slower than using WiFi. After extensive research and analysis I've isolated the problem to the Ethernet interface being throttled with a Link Speed of 100Mbit/s. This information is displayed running Network Utility.

I've tried multiple cables, and that is not the problem. I can connect a MacBook Pro to the same cable, and it shows a Link Speed of 1Gbit/s.

I've tried running the iMac in Safe Mode and with a new user account, but neither solves the problem.

I've contacted Apple Support multiple times and they suggested the following:
  • Reset NVRAM or PRAM
  • Reset SMC
  • Reinstall macOS from macOS Recovery
None of these resolved the problem.

Finally I used System Preferences > Network > Ethernet >Advanced > Hardware to manually configure the network, but when I tried to increase the speed I got an error message.

Next step is to take the iMac to the Genius Bar, as I suspect it is a hardware issue with the Ethernet port that is causing the problem. However, I thought I'd post here and see if anyone might have any additional suggestions to resolve this issue if, in fact, it is software-related.
Apple is aware of an issue with the driver for the network port on the iMac Pros but isn't really admitting it publicly. I know this through a developer of high-end audio network drivers for audio interfaces. I don't know if this driver bug has filtered through the entire iMac line - you didn't say yours was an iMac Pro - but it is possible.

Oddly, on the iMac Pro if you use a USB > Ethernet or Thunderbolt > Ethernet adapter, you side-step this issue. Of course, that doesn't help test for hardware issues - just gets you a working ethernet connection, but if your system is indeed a Pro, it's likely the driver issue.
 


Well, I took the iMac to Apple Genius Bar, and all the experts there were stumped. It was easy to confirm the problem on their Ethernet.

Their in-house network has startup volumes for recent OS's, but, for some reason, my iMac would not boot from any of these. Also had problems booting from one of their USB drives, so it appears this is a hardware problem with the Ethernet port.

Last suggestion was to erase the hard drive and do a clean install of macOS from Recovery Mode. Since I have both Time Machine and Carbon Copy Cloner clone backups, I tried this step. Unfortunately this did not fix the problem, so it must be hardware.

They've ordered a new logic board for me, which should hopefully resolve this issue.

Thanks for all the suggestions, and I'll post a reply on this thread when I get the iMac back and the problem is (hopefully) resolved.
 


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