I have been thinking about upgrading my Late 2012 iMac 27″ internal HD (spinner) to an SSD. That is a very difficult repair job, but it is doable. In line with this I have been looking for an app to measure the speed of my current hard drive setup.


The Upgrade

Why do an upgrade? Well, some stuff on my iMac is just kind of sluggish really. So, what are my alternatives? I can either wait until my iMac is 5-6 years old and then buy a new Fusion version 27″ iMac to the tune of $2,000-$2,500 or I can install a good SSD in place of the internal HD (not the Fusion SSD portion) for about $600. Yes, a new machine has a faster Fusion drive than the one I have now, but more importantly the whole architecture is faster. If I decide to do this I think what I would do is install a 2GB SSD drive in place of the internal, spinning HD and put everything (including the macOS) on it and not use the Fusion Flash drive at all.

So, the bottomline for me is to maybe replace the internal spinning HD with a 1-2 GB SSD drive. I will gain some speed, but how much. Enter a nice little app called DiskMark which is sold in the App Store for $4.99. It is a one horse band that measures the Read/Write speeds on drives.


When you open DiskMark you see this window:

Just click on the “Select Volume” button and select the volume you wish to check, in this case my internal Macintosh HD. Keep in mind this is a Fusion drive, a combination of a SSD Flash card and a normal, spinning HD. Here is what the app does when it selects your volume:

When it is finished (it takes about 30 seconds) it gives you the numbers. It does tell you to not use your Mac while the test is conducted.

I ran this test a few times, sometimes it comes in a little higher, but always around the speeds you see. So here is the deal, new SSD’s typically run around 500 Mbps (or more) for both Read and Write. Quite a speed improvement I would say.

So, what to do. I think it is worth it to upgrade the iMac to the SSD. It is a good machine, running very well. I really like it, but it is slowing down a bit. However, this is a very complicated procedure, not for the faint of heart. I don’t want to do it unless I am convinced it is worth while. I think what I will do is wait until macOS Sierra comes out and see if it is more efficient, faster, more snappy on my iMac. I can test the beta of Sierra in my beta install for a couple of months before it is released. That should give me a pretty good idea of whether to go ahead with the upgrade, or just use my original equipment for a few more years and then get a new machine.


If you want to check the hard drive speed of your Mac (and external drives as well) then I highly recommend the little app DiskMark. It does not test any CPU stuff, just the raw speed of your hard drive setup.