High Sierra iMac Upgrade

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Well, I waited a few days before updating my iMac to High Sierra to monitor any problems. I am glad I did because during that time about 20 or more of my third party apps had High Sierra updates. But, this morning I decided to do the update and see how it goes. Here is what I did to prepare along some of my observations about the OS.

Preparations & Install

I did several things to prepare for this install. I ran different backups of some of my data to external HD’s. I cloned my system using Carbon Copy Cloner. I ran some utilities to clean up the System. And, like I said, I installed updates to my mission critical Apps and other Apps as well.

Before installing the update to High Sierra I disconnected all my external hard drives. Then I ran the High Sierra update. The update took about 40 minutes. There were no real problems after it booted into my iMac. However, there were a few things that should have booted up in Startup Items that were not running. I just did a regular Restart and all was running properly.


I have several observations to make about macOS High Sierra regarding the physical properties of the iMac and how stuff works.

Physical Properties – I switched my iMac from a Fusion drive to a straight Crucial SSD a few months ago. Because I am now running a straight SSD, the installer updated my iMac drive to the APFS file system:

By the way, the High Sierra installer does not alter your externally connected hard drives. They will remain on HFS+. However, just to avoid any complications, I did disconnect all my drives before installing. I reconnected them after the install was completed.

The other observation about my iMac drive is the space. People have mentioned gaining some space on their HD after installing High Sierra. That is exactly what happened on my iMac. Here is Get Info of my Clone which is before the install:

The size of my old install left about 730 GB of free space on the 1 TB external drive. Now look at the Get Info on my current High Sierra install with APFS:

Because of the way the APFS file system handles drive blocks I gained approximately 50 GB of space!! That is pretty amazing!

OS Operation– Now, my observations of how High Sierra operates are with very little up time, but I think they may interest you none-the-less. High Sierra is fast! All my Apps launch faster. They seem to work faster as well. I am not imagining this, stuff really is much more responsive. Here is a typical test I run on my internal SSD using an App called Diskmark:

I would say these listed speeds are about 15 to 20 points higher than on the HFS+ OS.

Keep in mind, this is all running on my internal Crucial MX300 SSD. But then, so was my the HFS+ install. The APFS file system is just more efficient space and speed wise.

I know some people are having problems working with Network connected drives with High Sierra. That is mainly because Apple has deprecated their old AFP network connection system and replaced it with SMB which happens to be the industry standard. At this point, I cannot connect to my wife’s MacBook Air on our network. I will be doing to some research and report back on this in another article.


So far so good with my High Sierra install. My mission critical Apps all seem to work well. I have a lot of software so I am sure some things may have issues until they are updated, will just have to see how that goes. As far as I am concerned, updating to High Sierra is a Go at this time unless you are running Macs in a corporate environment. That is a whole other creature altogether.


  1. Hello Douglas,

    I found your website when I was looking for information about possible compatibility issues when installing High Sierra on 3rd party SSD’s. I also have Crucial MX300 flash drive, installed in my iMac about 10 months ago, 750GB version. I was wondering if you experienced any problems during the installation. I found articles on the Internet that for some people the installation fails – it’s either due to problems with Macs firmware upgrade or support for new file system on those 3rd party SSD’s. Did you perform an upgrade of your existing macOS or did you do a fresh install? I will appreciate your help.


    1. Hey See

      I upgraded to macOS High Sierra on the existing macOS which was Sierra 10.12.6. I had no problems. The installer did change my file system to the new APFS. I have not read too many problems upgrading to High Sierra on SSD’s. I think if you run some utilities on your current install (I am assuming it is macOS Sierra) making sure it is as clean as possible first, you should be OK. At any rate, having a good backup prior to instal is crucial (pardon the pun). I have a clone of my drive plus other backups of mission critical files. My Crucial MX300 runs High Sierra really well.

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