Over the years, I have run DiskWarrior immediately following the installation of a new OS. And always, numerous (many more then normal/routine) discrepancies are resolved.

But with the advent of APFS, I fear it may take Alsoft months, rather than weeks, to release a High Sierra compatible version.

Ergo, to the questions:

FYI: I only have spinning rust (on internal drives), so my High Sierra would (must?) be HFS+.

1. Presuming I go ahead and install High Sierra, would it still be okay to run DW v5.0, or is that of such risk that it’s best not to run it at all? I guess the real question is: What would you do were you in my situation?

2. At the risk of biasing the replies, my first thought is to install High Sierra, make several clones, and then test DW 5.0 on one of the clones. Or, is that too fraught with peril?

My gut feeling says to not let third party tools ‘fix’ a new OS with tools from a time before the OS. The repair/optimize tool might mis-interpret some situation/finding and make things worse. Just like Onyx, the tool should be OS version aware/the version should match the OS version.

If you are willing to make several clone volumes, then by all means let us know how the experiments go.

I'll guess that attempting to run an outdated version of DW on a clone won't be perilous, but neither would I have any faith in the results it returns if it runs.

At your discretion, you may format your HD to APFS when you install High Sierra, but it is not mandatory.

Technically HFS+ is still HFS+ whether it is with Sierra or High Sierra and Diskwarrior should be okay. However given there are a lot of internal changes in High Sierra other than the addition of APFS I would never use any volume repair software that has NOT been certified for use with High Sierra.

Personally, I have not used Diskwarrior, Drive Genius, or TechTool Pro to either optimize my drive or check/repair the volume structure in years. MacOS has been stable enough that those tools simply have not been necessary. File and/or volume optimization should still be useful on a rotating rust drive formatted HFS+, but counterproductive on any SSD or HD formatted APFS.

I have run High Sierra betas on both SSD and HD volumes with no obvious difference other than a slight performance improvement with APFS. But to my way of thinking the additional features of APFS plus the excellent stability of MacOS in recent years lets me run without third party volume repair utilities without any particular concern.

For that matter, I'd be pretty hard-pressed to come up with a new topic for a frequently asked question at this point in time.

Many thanks to y’all for sharing your thoughts & expertise.

I’m still a bit undecided re trying DW. As I won’t be using APFS for now, some of my apprehension is a bit abated. For sure, if I do use it, it will only be on an external HFS+ volume.

I know of no way to test DW other than to run it and then use that volume for few days. And even then, I could still have problems that just haven’t surfaced.

It will be a few more days until I’m able to install High Sierra. And when I tell my wife that Reunion has not yet been High Sierra certified, things may experience additional delays. Still, promptly after my High Sierra install, I’ll post back re my successes (or not).

This DW question is similar to the one that came up on MacUpdate a while back regarding Applejack.

People were posting how to get it to run despite the developer's having abandoned it, but the underlying fact was that even if it ran, it wouldn't be doing the job it was designed to do, because Apple had added to, subtracted from, and relocated so much of the OS with which it dealt...precisely the reason the dev had abandoned it.

I'm in no rush to install High Sierra. There will always be bugs in a new OS and, as is my custom, I'm waiting until 10.13.1 or 10.13.2 to take the plunge. Plus, I want to see how many of my apps will still function. A little patience might be in order, Harv. What's your hurry?

Earlier today, I did take the plunge. ...All is well so far with the OS.

I really don't have any specialty apps, which might keep me waiting for their compatibility; so, I'm happy proceeding with upgrades (of course, after TM backup & CCC5 clone) if the Beta testers previously said the beta versions were smooth.

Regarding DW (as well as TTP) and over the last several years, I’ve felt less inclined these utilities were as necessary as in prior years. Following issues discussed about TTP’s current version (only Sierra compatible), TTP additionally can never deliver a fully compatible, next version until a macOS upgrade has been released & TTP has fully tested; and even then, TTP doesn’t recommend certain tests on SSDs. DW has now been priced at such a level & DW5 doesn’t recognize APFS formatted drives so that when taken with recent, macOS stability, I think it’s also less a “must have.” Between Cocktail v11 (10.13 compatible), CCC5, Time Machine, & Disk Utility, I feel I’ve got my System covered for my needs.

Thanks again, dear friends.

While I do not (typically) install the new OS on day one, I seldom wait more than 3 weeks. A big part of my promptness has to do with my wanting to learn as I go. A good example is my iPhone 5. In the next 90 days, I'll be switching to the iPhone X. And when that happens I'll have a vey steep learning curve ahead of me, literally hundred of new features and capabilities, most of which I'm only vaguely aware.

Still, compelling arguments are made and they do influence me, as does the general chatter/reviews on this and a few other sites.

And of course, if DiskWarrior becomes abandonware, then I'll promptly drop it. Otherwise, it will remain in consideration.

And if all that isn't convoluted enough, me thinks it's time to replace my 2010 iMac. And if I do that, then I'll skip the High Sierra install and merely run Migration Assistant from my new toy.

Now, back to work on the Grand Unification Theory-

Alsoft just posted this:

1) DiskWarrior 5.0 is compatible with macOS 10.13 High Sierra.

2) Mac OS Extended (HFS Plus) disks can be rebuilt as before. This includes Fusion and Time Machine disks.

3) Apple File System (APFS) disks are not recognized by DiskWarrior 5.0 and will not appear in the list of disks.

4) Due to the ever enhancing security of macOS you will need to first "Allow" the system extension portion of DiskWarrior to be loaded on your Mac. The first time you rebuild a disk with DiskWarrior 5.0, the system extension will be blocked at step 8 of the rebuild. This will result in a "OS X services failure" message in the DiskWarrior report. You will only need to allow the system extension once.

NOTE: The above link has additional data re a new version, APFS, etc.

Bad link, Harv; it looks like you've got to delete the leading http://.