• I just bought a brand new 1TB SSD for my late 2012 mac mini. Should I reformat the SSD to the journaled using an external adaptor first? Asking this because I use to upgrade my hard drive before, the system unable to detect my drive and went straight to internet recovery. Forcing me to install the legacy Lion OSX.

    • You don’t have to reformat the new SSD using an adapter; you can just launch Disk Utility from the Menubar once the installer loads; this can also be done in Recovery Mode. What’s not entirely clear is if you are trying to upgrade an existing System, or trying to clean install. Presumably, sine yo7 are posting on this article, you are trying to install Mojave; just be aware that Mojave wants to be on APFS, not HFS+ when installed to an internal SSD. I suspect that is in part what wall you hit.

  • You don’t mention a firmware update being required to install Mojave. Mid 2010 Mac Pro running 10.13.6. What is the nature of the FW update and why is it needed? Yes, I know about video card reqmt. Already have that.

  • this has never happened before-the installer do not want to install the system on my original start up disk.I have iMac 5K ,late 2014. What might be wrong?

  • If you don’t do a clean install, run First Aid on the dis k you are going to install on first. This will save a lot of hassle if there is a problem that could cause the install to fail. (My lesson learned from High Sierra).

    I had no problems with Mojave other than the time took. I started at 10 PM and finished at 2 AM. (My wife wasn’t happy about that, but then she doesn’t like me rebooting when she is using the Apple TV.)

    Only surprise was it converted my hard drive into an APFS Volume. I heard a lot of talk about that not happening with High Sierra and no mention of it leading up to Mojave, that it took me by surprise to see the change the first time I opened Disk Utility.

  • If I opt for a clean install to avoid legacy detritus, will Time Machine still recognise my ‘new’ hard drive and system?

  • If I do a clean install, will Migration Assistant move my applications as well as my data? I’m concerned because, in past updates, Microsoft told me I had used my office Activation Code before and I had to purchase a new copy of Office if I wanted to activate it.

  • I came for expert advice on choosing to upgrade vs. clean install, but instead this was a “how to” for both.

  • The v2.3.15.1067 firmware update, available on the OWC web site, resolved the issue of the 10.14 Mojave installer reporting that it could not install on my “third-party” storage. My first re-installation re-attempt went off with a hitch, and operation is smooth and flawless now.

  • The article doesn’t attempt to advise, let alone answer the question posted in the headline; it only outlines the steps for either choice; so I assume it is instead attempting to invite discussion on the subject, n’est-ce pas ?

    I always laugh and shake my head every year listening to the pundits (most of whom came from Windows) discuss how they do a wipe and reinstall every year and/or with every new Mac, as though the hours and hours, if not days of reconfiguring and reauthorizing all your software and restoring all your preferences and third party tricks and tools and homemade services, scripts, etc., is somehow a magical curative to problems that never existed. Were you having troubles with your current install? No? Then why are you blowing away that foundation?

    As I type this on my current machine, I am sitting on top of a single-threaded-life install that has merely been upgraded, release to release, years after years, now year after year, since the days of the first Mac OS X 10.1 Cheetah release in 2001 — and I just can’t recall with certainty, but my fading memory says I took it all the way from the public beta.

    Further, it has simply migrated from Mac to Mac over the years, and it has even forked itself onto multiple Macs running to this day. And we pulled our old Mac OS Classic systems over from old Mac OS 9 System Folders over the network with AFS.

    Looking in my preferences and Library folder, I have objects with creation dates from 2004; and I’m sure there are objects still onboard older than that; I know I used to blow out prefs and libraries during troubleshooting (back when I was coerced to run Adobe and MS products that always misbehaved), and usually I merged the originals back in after identifying the bad object(s), but apparently in 2004 I was lazy or determined it wasn’t worth preserving; or everything prior had at one point or another required replacing.

    Do I have 17 years of cruft on board? Sure. But who cares? It’s *NIX; nothing is called or loaded unless told to do so; it’s nothing but a few MB, maybe even a few or several GB, if I were to spend hours and days sorting and cleaning said cruft and keeping a tally. If I were stuck on a MacBook Air with a tiny hard drive, I might worry about it. Hard drives are cheap. SSDs have been plummeting in price the past few months ( I paid $325 each for four 1TB EVOs not more than a year ago, and was thrilled I got them at that price; today, I can get the newer version for $175 or less).

    Will I do some cleanup as 32bit apps are completely deprecated in 2019? Probably; but I still have Carbon apps and components I haven’t bothered to delete, so there’s a chance my desire to just do work *with* my computer, not *on* it, will prevail.

    And, this is true not only for me, but for the fleets of employees and Macs that have stuck around over the years; we never clean wipe until its time to sell; then it’s a clone, carried to the new Mac, which is overwritten with the old Mac’s clone. (the only times this has been a problem is with day zero Macs whose OS is newer than what is available to the public; so the merging/migrating is a bit more complicated; but we’ve never once bothered with rebuilding from scratch).

    And, for those already typing a rebuttal, yes, I have, with pretty much every mature OS version, done benchmarks against a virgin, pristine installation; there has never been a repeatable, let alone appreciable difference in performance.

    If you don’t have much third party software, or your own customizations, and a clean install is worth your time to give you some piece of mind, go for it; but you’re running macOS and not Windows for good reason; if there are installed items causing your troubles now, just remove them; it’s not like you’ve got a registry or .dll dependencies or anything remotely similar. The only troublemakers used to be Adobe and MS, and a couple others that married licensing to a specific Mac by serial number, or even did nasty stuff by writing licensing info to the hidden volume structure maps on a particular hard drive. If you’re just upgrading an existing Mac, even that isn’t an issue.

    Do upgrades occasionally bork? Yup? But so do point-release updates, and we’ve always been content to just re-run the latest combo updater, or restore from clone and try again.

    Again, it’s *NIX; you don’t have to freak out about dependencies; if a library or kext or plist is corrupt, just overwrite it and live your life.

    So, which is right for you? I say, with nearly two decades of experience, it’s 98% likely you should just upgrade; but maybe wait a few weeks until you hear there are no major issues, if any words in this article made your eyes glaze over.



    • If there was a like button, I would have clicked on it!

    • I’ll second what Frederico is suggesting, just upgrade and please don’t forget: it is a well organized NIX.

      All the best,

    • Frederico, makes good sense yr suggestion. Last couple in-version updates I have downlded the combo update file. Question – Since this is a major version upgrade, if I do just the upgrade (not fresh install), does it help/would you recommend to do combo file update on first Mojave update? Am not expert with all the ins & outs so hope it is a sensible question. Thanks

      • Galone, no, I don’t advise doing the combo updates prophylactically. If you have issues, it’s an effective first effort, but usually you’re facing individual app incompatiblities, and you are better off just letting everyone else upgrade first, and wade through the community/developer reports for the apps you use or most depend on before upgrading. If nothing else wait for at least the .1, if not the .2 update, and be certain you have a CLONE standing by so you can just revert, as opposed to going through the horrors of a downgrade restore from Time Machine.


    • I just did a clean install of 10.13. I’m an indie Apple tech, and over the years I have found that performance improves less with clean installs than it used to in the 10.3-10.6 days, though I can’t remember what installs were like in the system 6 / 7 days… I think I messed with those system 7.5.5 discs… like, way tooo much.

      What I’m saying is, YMMV.
      I have definitely had HUGE gains in performance from performing a clean install of an OS. So, what I used to do, was just do clean installs when it was time to upgrade. I would upgrade in place, and then do a clean install and manually migrate all my files. I hardly ever us migration assistant on my personal machines. However… is it a royal PITA? Yeah… oh, oh, yeah… So, most recently I think I went from 10.10->10.11>10.12>10.13 before doing a clean install. Granted, this happened much more rapidly than it has historically. I’ve tended to stay with an OS until two more came out, then I would upgrade only once. Why? Because, Murphy’s law strikes me so hard.

      I have sooooooooo many problems on my computers… I’m still a Mac user, because I don’t consider windows a real platform alternative. I have a Mac and hundreds of servers connecting to my computer simultaneously as it is. I can’t imagine how assaulted I would be if I was a windows mark.

      And, before you finish typing your rebuttal. Benchmarks? Hah… no… do real world testing. Benchmarks can only tell you so much. I don’t think your experience isn’t real Frederico… I’m just jealous as ••••!!!!

      • Not as much a rebuttal, but an expansion of the conversation:

        — By benchmarks, I do mean Real World testing of applications, user files and workflows, and, especially, interaction between apps, particularly as it pertains to scripts that perform tasks across multiple apps. We just never see anything appreciable, let alone repeatable.

        — one major reason I see fewer and fewer people experiencing non-placebo performance improvements in recent years is that since 10.10 to 10.11, unlike 10.1 – 10.9, is that more and more and more of us are on SSD and Fusion drives — of course a clean wipe on an HDD is going to perform better, almost no one was or is defragging after the mis-hype of “automatic defragging” AKA Hotfiles, morphed into a myth that ALL files, not just System files *under* 20MB in size, were being not only defragged, but prioritized to the fastest portions on the outer platter edges.

        — If you were still defragging HDD, especially older ones with fewer platters, which had poorer MBps and much smaller caches, bother before *and* after upgrades, your performance gains from a clean wipe were almost impossible to detect, if any; this was further solidified if you used multiple partitions and drives, keeping your most-used data at the fastest portions of a drive, while simultaneously keeping your VM also not only contiguous, but also nearer the outer edges of the platter.

        — To this day, we defrag spinning disks (that host data that needs to be fast) — it matters, and is provably beneficial for certain applications, though admittedly less so for modern drives with lots of platters and fat caches that can push 180MBps in the first 50% of the disk, as compared to what we once thought was fast if you could get 80MBps In the first 20%.

        — RAM also got cheaper and Apple finally stopped being quite as stingy, further reducing VM dependency, and thus improving overall perception of “snappier” feelings after both upgrades and clean install (once all the new caches, Spotlight and Photos indexes were done being built, anyway).

        — please also note: I never claimed we did not and do not still experience occasional inexplicable breakdowns and system corruptions; we can choose to do a “dirty reinstall” (aka, System Restore), or, unlike most users, just drop back to the last known-good clone, re-update as necessary, and life moves on with minimal downtime and zero reconfigurations and app re-installations.

        Users who don’t employ a regular cloning strategy may not have adequate success with a dirty install, and a clean wipe is the only real option; it sets up and contributes to a mindset that a clean install is the best install.

        — a further point that allows our strategy to succeed, is that every machine is configured with separate user/data drives/partitions, as well as (as far as it is possible) separate apps/utilities partitions/drives; this allows us an extremely fast restoration process from an isolated System/System apps clone of 20-80GB, instead of 100GB+, gawdforbid terabytes of data requiring hours upon hours to restore in a unified disk structure.

        Most users aren’t even using Time Machine, let alone cloning, so, yeah, maybe sometimes there is no viable choice better than a clean install; but i did preface my position with (essentially) “if it ain’t broke, why are you throwing it away?”



  • Thanks Tom, but neither works because I get “Cannot install to third party storage” error. I have Aura as my main SSD. I used a third party external SSD for my clone. Neither is seen as an Apple disk. Failure.