Backing up to disk images in Catalina?

[nephdoc]

Originally Posted by dnanian

That doesn't make sense. We don't copy the system volume if it's not changed (we don't even evaluate it), so there's no need to skip it: you're effectively doing what you're suggesting already.

It does make sense on another level. If you're me, and well behind the basic curve on how SD works, discovering what it does is in any way akin to what I was suggesting shows that I actually had an idea that turned out to be right!

It's like this: In medical education, there's a time honored educational theater called the CPC (clinical-pathological-correlations). A famous professor from another medical school, visiting and showing off his diagnostic skills, is presented the story of a single patient. Typically, that story ends with a critical diagnostic test that establishes the cause of the patient's problems, or sometimes with the patient's demise with the cause of his or her problems still undiscovered. The visiting honcho is not given the result of that test, or even what the test was (unless the patient died, and then it's obvious that it will be an autopsy.

Then, the hotshot from Boston, or Cleveland, or San Francisco, or Vienna, or wherever, takes over and displays his perceptual magic, after which the pathologist appears from the basement to tell everybody what was REALLY wrong with the patient.

Typically, after the wizard from St. Elsewhere's skills are affirmed or shown to be lacking, the next slide in the PowerPoint (or, in Apple's resurgence, Keynote) presentation is a summary of all the Med Students' diagnoses.

The story goes that in one such bit of mental acuity theater, ALL of the medical students but one had the wrong diagnosis, as did the visiting maven, EXCEPT for a guy (we'll call him Jim) who was clearly known to be the class dufus.

The patient's original complaint had been something wrong in his belly, which turned out to be an enlarged spleen. Now, there are literally dozens, if not hundreds of causes of "splenomegaly," and the greatest diagnosticians are legendary for ferreting out other clues that lead to inference of the cause of an individual patient's diagnosis when that's the presenting abnormality.

The out-of-town professor in this case didn't know that his famous talents had been bested by the local class clown, so he was a bit surprised by the giggling and murmuring when Jim's name appeared on the giant monitor as the only person to get the diagnosis right. The correct diagnosis had been "primary malignant sarcoma of the spleen," and Jim's diagnostic proposal had been "spleen cancer." Technically, sarcoma and carcinoma are a bit different, but still, Jim had been fundamentally right. So, the visiting prof asked him to stand and run through his own thought processes that had led him to the correct diagnosis.

Jim replied, with no hint of embarrassment, "so, what ELSE makes your spleen get big?"

So now, Jim #2 asks your indulgence for 2 more questions:

1. Do you know when the Catalina-compatible 10.15.5 SD will be ready?
2. Do you have any inkling whether a typical user forced to work from his/her clone for a while would be able to tell the difference between one based on a Sandisk portable external with USBc interface vs. OWC's NVMe "blade" SSD connected via TB3?

By the way, my own time in medical academia predated Mac OR PC, but by the time I was attending giant hotel annual meetings of professional societies as a practicing doc, EVERYONE had given up on the "Diazo-Blue" acetate transparencies that would melt from the heat generated by the thousand-watt incandescent bulbs that projected their content on enormous screens in the hotel ballrooms if the speaker lingered too long on one slide.

EVERYONE by then (late 1980s-early 90s) used their HP or Compaq Windows laptops, and typically when one presentation followed another, either the presenter would bring his laptop to the front and fumble with connecting it to the projector, or with rebooting the hotel's laptop, or stuffing his presentation floppies into the computer, or getting his presentation to fill the screen rather than being overlain by his grocery list in a window, or the IT guy would fumble with the projector refresh rate, or they wouldn't have the proper interface cable.

Inevitably, as the audience began to murmur like an angered British House of Commons, someone would call out from the audience "GET A MAC!!!!!!!"

Thank you so much for your unbelievable patience and generosity with your time!