Please explain what "Keep On Root Device" means in Timeshift "Select Target Device"

[Daisuke]

I am not really sure of the meaning of the "Keep On Root Device" option which appears on the Timeshift "Select Target Device" page. This comes up as part of the Restore operation.

I used it to solve a problem which I describe here. However, I am not sure that is what it is intended for.

[AZgl1800]

that would keep the 'target' Timeshift folder on the /root partition as the OS is running on.

a terrible idea that can easily lock up the partition by running out of space.

Always choose a separate HDD/SSD or at a minimum create a separate Partition for Timeshift, so that your OS won't be impacted by the large files created by Timeshift.

my drive looks like this, and note that it is dedicated to Timeshift and a few other "backup utilities"

[pbear]

that would keep the 'target' Timeshift folder on the /root partition as the OS is running on.

Sorry, but that's incorrect. The OP is asking about an option during the Restore process.

Daisuke, what's going on there is that Timeshift doesn't try to parse fstab to select where to restore files. Instead, it expects the user to know whether they moved a folder or sub-folder to a separate partition, then say so on that screen. Keep on Root Device is the default because that's the default at installation.

For example, /home is usually on the root partition. If you put /home on a separate partition, you have to tell TS on this screen.

[Menard]

I had some problems at the beginning when I was using default settings, so then I allways unchecked the two checked items in this box ... and all went well ...
except one time because I wanted to restore on another partition and it seemed that it could be useful to let these 2 items checked, and it was a good idea ...

[Daisuke]

Always choose a separate HDD/SSD

Thanks for the reply! I agree with this completely. And I do have a separate drive for TS backups.
In the image you post, it looks like your backup area is another partition on the same drive holding your Linux system. If this is indeed the case, and the drive itself were to fail, it will take out not only your system and home partitions but also all your TS backups. I just mention it as something to consider. We are in complete agreement on the drives however, as all my SSDs are Samsung, mostly EVO 860s, but now EVO 870s, as the unbeatable 860s are no long made.

what's going on there is that Timeshift doesn't try to parse fstab to select where to restore files. Instead, it expects the user to know whether they moved a folder or sub-folder to a separate partition, then say so on that screen. Keep on Root Device is the default because that's the default at installation.

For example, /home is usually on the root partition. If you put /home on a separate partition, you have to tell TS on this screen.

Thanks so much for the very helpful and informative reply which clarified the meaning of "Keep on Root Device". As a clueless new user, in the setup, I did not expressly exclude partitions mounted on /data and /share. Even so, TS was smart enough not to snapshot any of their contents aside from including the mount point directory, i.e. /data and /share. It does automatically exclude /mnt and /media directories. However, other mount points like. /data and /share need to be explicitly excluded by the user as you suggested in another post.

As a novice user of TS, I incorrectly assumed it restricted itself to / and /home partitions and only allowed restores on the original drives. So it is interesting to learn this is not the case.

Following your advice, I have started to explicitly exclude these partition mount points. Interestingly, these still show up in the "Select Target Device" page, but I no longer get the dire warning that their entire contents will be replaced! However, this seems to be a bug since this Select Target device page also presents sources to be restored (in the left hand column) as well as the restore destination or target (options in the widgets in the right hand column). So it appears that TS is asking for a location to restore the contents of directories which it has not backed up and which have been expressly excluded. Here is a screenshot.

I had some problems at the beginning when I was using default settings, so then I allways unchecked the two checked items in this box ... and all went well ...except one time because I wanted to restore on another partition and it seemed that it could be useful to let these 2 items checked, and it was a good idea ...

Thanks for the tip. I think you are referring to the extra options in the "Boot Loader (Advanced)" dialog box. I always uncheck those too because I have a dual boot system and others have reported problems when they leave these default boxes checked. But it is good to know that if you are restoring to a different partition that they work!

[AZgl1800]

I have bought at least a dozen SSDs, and not one of them has ever failed.
That is the least of my worries.

Plus, I have Foxclone Image backups if needed.
Plus, I have /home backups on an "offline USB drive'
Plus, I have Aptik backups to restore my Apps...

my Daily Driver is a Laptop, no room for extra HDDs/SSDs, so separate Partitions it is.

[pbear]

... I did not expressly exclude partitions mounted on /data and /share. Even so, TS was smart enough not to snapshot any of their contents ...

Open Settings, click Filters tab, then Summary button. There's a long list of default filters. Didn't notice a filter for /share, but that might be inherent in rsync, which is what actually does the file copying.

[Daisuke]

I have bought at least a dozen SSDs, and not one of them has ever failed.
That is the least of my worries.

Plus, I have Foxclone Image backups if needed.
Plus, I have /home backups on an "offline USB drive'
Plus, I have Aptik backups to restore my Apps...

my Daily Driver is a Laptop, no room for extra HDDs/SSDs, so separate Partitions it is.

Yes, everything is tradeoffs and I agree you have a very good backup plan. So many people don't have any backups!

I would like to try Aptik but I admit I do not understand what it does. I find each back up tool requires some study. That will be the next thing I tackle after BackInTme. Thanks for the tip!

[Daisuke]

Open Settings, click Filters tab, then Summary button. There's a long list of default filters. Didn't notice a filter for /share, but that might be inherent in rsync, which is what actually does the file copying.

You are a font of knowledge on TimeShift. Thanks for this tip. I will post the a snapshot of this window below. I confess I do not know the difference between *, ** and *** when excluding files and directories. I hope you will enlighten me on this point

As you can see, barring my ignorance on the meanings of the asterisks, the mount points of all the external drives seem to be well and truly excluded by TS already. I simply added a couple more at the end which seem redundant.

This still begs the question, if these are excluded from the backup, why are they being offered as candidates for restoration? Again, this does seem to be a bug, but I defer to you for an explanation.

[pbear]

Per the rsync man page, two asterisks matches any path component, but stops at slashes; three matches anything, including slashes.

To be honest, I've not tried to understand the point about restoration, as your setup is very complex (to my mind, needlessly so) and I've never run into the issue you describe. As for whether it's a bug, maybe, but developers can't anticipate every scenario.

Bear in mind, the purpose of the Select Target Device screen is for you to confirm the restore points. Bug or no, it's your job to make sure they're correct.

[mikeflan]

two asterisks matches any path component, but stops at slashes; three matches anything, including slashes.

If I am reading this right that needs to be corrected to:

[pbear]

Hmm, what's the source for that version of the man page? This link I gave (which I believe is the official man page) has different text. You can find it quickly by searching for the text string ***, which appears only once. There's a bit of a lag for the version of rsync used in Ubuntu (inherent in stable release), but not different on this point for either 20.04 or 22.04.

[Cosmo.]

pbear, following your link I get the same, what mikeflan has partially showed as screenshot. About 10 lines below (not in the screenshot) there is also the explanation for ***. The other 2 links (your last post) give exactly the same content, only a little bit different formatting.

[mikeflan]

Yes, it was from the pbear link. And his "***" is about 13 lines below what I posted.

[pbear]

My bad. I should have been able to figure out the screenshot was an earlier part of the same section of the man page. In my defense, it was morning here and the coffee hadn't kicked in yet.

Does anyone have a better brief summary of what the asterisks mean from a practical perspective for the Timeshift filters? Telling users just to read the pattern rules section of the man page strikes me as not very helpful.