Yes, I agree with this method, too.
Yes, that directory would be stored on and run from the Data Drive.
It would behave normally from your point of view, just mount and run from a different location.
This is true if you have your entire Home Directory on the Data Drive.
If you opt for Zorin OS Lite upon release, I think it would do you a lot of good to install by setting up the partitions with /Home a partition at the outset to make everything meshed, smooth and easy.
Do you mean I should avoid the method proposed by 337harvey above?
I cannot not say to avoid since his method is also a valid one.
There is more than one way to solve the issue for sure.
It all depends on how much effort you are willing to make to opt for one solution or another.
You mention partitions here, but I just want my Desktop (or my whole Home directory if that's safer/easier than just doing the Desktop) on my Data drive primary partition, so I only have to back up one location. I'm unclear as to whether I should do the steps suggested by 337harvey or not - I definitely don't want to mess with extra partitions.
In Windows I could just right click on the Desktop folder and choose to store it on any drive, so could pick a folder called Desktop on my Data drive. I want to minimise my number of partitions, I already have four partitions across three drives! 
So do you:
That symlinks, same as Linux does. However, in your case, you want to be able to create back-ups of the data and you do not want to make a back up, only to find it only saved a bunch of Symlinks instead of the actual data.
I just want the minimal effort one that lets the Desktop (or Home, including Desktop) reside on the data drive rather than the OS drive. No new partitions, so that it is simple and I just have one drive/partition to back up. Ideally just a Terminal command or config file to change in order to make it happen. In Windows it's a case of right click, Move, choose new location, Ok. Something that simple would be ideal - I'm already a bit lost by talk of partitions and symlinks. 
Yes, I definitely want to be able to back up my data drive and for it to back up every file on my Desktop as well! Without that I'd be better off just sticking to my current process (two backup processes for each backup - one for Data drive, one for Desktop).
exactly. The best and safest way to accomplish this is in a partition. In the old days of MBR, having more than Four partitions could be problematic. But in these days of GPT and EFI, that is no concern at all. You can have a hundred partitions if you want. Having more partitions is a good thing, more often than not.
It's probably me misunderstanding, but doesn't an OS treat each partition as a separate drive? And since backup synchronisation software needs a root folder to start the comparison, if my personal data was on three partitions I'd have to do the process three times for every backup? Whereas if it is on one partition (what I was hoping to achieve here, with my personal data folders + Desktop [or Home] all as folders on one partition) then I can do a full backup and synchronisation in a single step? As such, more partitions would be extra steps, whereas I am trying to do fewer. But I may well be misinterpreting how it works. A lot of basic things are confusing to me!
(Yesterday I had three: a thunderbird profile in a hidden folder .Thunderbird, but my backup software wouldn't let me browse to the hidden folder as a source; paths to a file in one piece of software are different to paths to the same file in another; and the backup failing to back up any of my desktop shortcuts to folders on my Data drive. All are issues to unravel in the future ...)
Yes.
No. Or at least, not necessarily.
If your Back Up tool (whichever you are using) only allows backing up one partition at a time, then that tool is quite limited in its design. Almost any I have come across allow you to set up the directories, partitions or drives that you want included in the back up, in one go.
I do not know which backup app you are using, but I simply copy and back up the entire home folder to avoid such issue. I much prefer manual handling of my personal data rather than let application to decide.
Dealing with such matters since pre DOS era, I always have this innate untrusting for an automation. Call me an old school, but I had some unpleasant surprises in the past.
I have never used a backup tool that did not critically fail me.
I also only do back ups manually to this day.
It's scary, to be sure! But synchronisation is important because most OSs seem to have unintelligent drag and drop for hundreds of thousands of files - they can't generally work out which ones haven't changed and don't need moving. The thing I like about sync software is it only moves new files; it mirrors my current data to the backup, saving hundreds of gigs of file transfers each week.
But aren't you then at the mercy of the OS? As in, the first time it finds the same file in both place,s you can only choose to replace the destination one (in which case it copies hundreds of GB more than it needs to) or it doesn't update the destination one (so the backup isn't current). It also doesn't delete files from the destination that no longer exists on the source. Unless you delete the whole Home folder from the backup first? Then, again, it is copying loads of files that were already there and maybe hadn't changed.
The thing I like about sync software is it only moves new files; it mirrors my current data to the backup, saving hundreds of gigs of file transfers each week.
The thing I like about sync software is it only moves new files; it mirrors my current data to the backup, saving hundreds of gigs of file transfers each week.
I have one for Windows backups, one for Linux. They may have those features, but scanning the changes before they commit would be much more complex for my brain if it is showing multiple partitions at once. As it is, I'm quite good at skimming the list and seeing that the changes are what I'd expect.
My sync process has never failed me, and it saves backing up unchanged files. It's just simpler to do it from a single partition to the backup (hence wanting to put Desktop or Home on the same partition).
Many thanks! Before I try this, are there any implications or possible problems I should be aware of? (I don't use Timeshift so that won't be a worry, I use FreeFileSync for backups at present.)
So I guess the first time I do this, I create a folder called Desktop on my data drive, copy everything from the Desktop to it, then Ctrl-Alt-t and type the following?
mkdir ~/Desktop/Desktop
ln -s ~/Desktop/Desktop /mnt/sda2/Data/Desktop
And if I reinstall the OS (e.g. when the Xfce version of Zorin Pro comes out) I would just do the two terminal commands again to point Zorin at my existing Desktop files on the Data drive?
Then whenever I do a backup of my Data drive, I am also backing up all my files, folders and shortcuts on the Desktop?
Would changing the path in user-dirs.dirs as mentioned here be a more foolproof solution for me if there might be issues with the symlinks method?
i.e. I would change
XDG_DESKTOP_DIR="$HOME/Desktop"
to
XDG_DESKTOP_DIR="/mnt/sda2/Data/Desktop"
?
I had recommended a directory on your desktop that points to your data folder holding the necessary items. Doing the reverse would have possibly only saved the symlink. What i described in detail put the symlink on your desktop and the files/directories in your data directory. This left your desktop on your system drive/partition and anything that wasn't pertinent could be stored there.
If you're storing everything that is important on the desktop, you may want to consider either having a home partition or learn how to change the default file locations for the bookmarks in the system (symlinks to commonly used directories).
[quote="337harvey"]
I had recommended a directory on your desktop that points to your data folder holding the necessary items. What i described in detail put the symlink on your desktop and the files/directories in your data directory. This left your desktop on your system drive/partition and anything that wasn't pertinent could be stored there."[/quote]
Ah, that makes sense. I do something similar when I use the GUI to create a shortcut to a folder, then cut and paste the shortcut to the desktop. What you suggest is definitely the simplest solution, but unfortunately that then means when I click on the link I just see my files and folders within the file manager, so things are in a list or arranged block of icons. I actually use the full desktop like a real physical one with piles of things arranged by project. So I use one corner for shortcuts, one for long term projects (with files and folders in a row for the project they relate to, furthest right to be tackled first), another area for short term ones etc. Then I can do Super+D to view it all at any time, and see my current progress. The data drive is mostly my long term storage/archiving. (Not sure if I have explained that well.) So I need to see the files and folders on the actual desktop, arranged by group.
The partition option was suggested by someone else, and I can see how it's a good long term solution for many people. I don't want to back up the whole Home folder, just the Desktop subfolder, which is the only one I restore when I install an OS. Plus the partition would mean doing two steps for my synchronisation backup, one for each drive/partition, which is what I already do - by storing the desktop on my data drive I can cut that down to a single step each week (just backing up my data drive). The software gets pointed to a source and destination, then compares them and all subfolders, and only copies changed or new files. Currently I have to do that for the data drive, then the desktop folder on the OS drive, but by getting them in the same partition I would only need to then do it once each backup. (Again, I hope that makes sense!)
So the bookmarks solution, would that be this one https://laszlo.gazsi.net/how-to-change-default-folders-on-ubuntu/
i.e. I would change
XDG_DESKTOP_DIR="$HOME/Desktop"
to
XDG_DESKTOP_DIR="/mnt/sda2/Data/Desktop"
?
I think Gnome doesn't let me change that file (if I do, it disables the right click menu option to create new documents), but when Zorin Pro Xfce comes out, I am hoping I'll be able to make changes to that file, so if this would work then it seems like it would be the solution I've been looking for.
Many thanks!
I fully agree with you.
Such heavy modifications should work much better in XFCE than Gnome from my experience.