Why System Snapshots?

[kmph]

Gave Lm19 a try... and it wants me very badly to set up system snapshots.

OK I get the reasoning... if an update breaks something etc... But I'm still in doubts about this feature..

1. You want me to enable daily snapshots and boot snapshots. Wow thats a lot of snapshots! With that many snapshots though, why not simply... make Mint a rolling distro? Stability is the reasoning behind allowing multiyear delays wrt shipping new versions of software to Mint. But that may snapshots...+ the recommendation to update everything seems to... as if the devs' current policy was that they're moving from the hard requirements of stability (that were not always being met in past tbh) and instead they say, "if anything breaks, just restore a snapshot". But with such a reasoning they could make Mint a rolling release as well. multiyear delays + lots of snapshot = something seems overkillish, something seems too much. Either strive to provide as much stability as possible to make snapshots unnecessary... or ship new software...?

2. Were to store the snapshots? Connected problem: Only snapshot system files or treat snapshots also as a backup facility to backup personal data?

2a) If only snapshot system files, then we can very well store snapshots on HDD... BUT then we have to have 2 backup facilities, one for system and one for personal data, which is too much again! Also: Windows has this annoying feature of randomly deciding it needs to use 100% of my HDD. The results are performance degradation and I wonder when will Windows finally kill my HDD? Is this coming to Mint as well?
2b) If personal files as well... Then we shouldn't store snapshots on HDD because one big reason to store backups of personal data is to protect them from dreaded HDD failures! So we should store them externally. Then again! - externally means where? My computer is a laptop. I refuse to have an USB disk connected to it all the time, thats just impractical. But then if I connect the USB disk manually then I wont set scheduled snapshots the system wants me to set! Also: I used to be using LuckyBackup to backup personal data onto external HDD. I dualboot windows; to make things easier (backup from one place) I was using lucky backup to backup personal files stored on windows as well. Can snapshots do this?

[gm10]

1. Up to you whether you need it. I have it enabled but I only run weekly snapshots. I've yet to need to restore one. Boot time snapshots sound like a terrible idea to me.

1b. Your rolling release argument is completely missing the point. LTS releases still receive bug fixes, that's the whole point ("long term support"). Nobody can help you if you don't want to install bug fixes, so I won't comment on that further.

2. Snapshots != backups. If you were to include personal data (your home folder is excluded by default) then restoring a snapshot to restore a previous system state would also restore that same previous state to your personal data. In almost all cases that's not what you'd want.

[kmph]

Your rolling release argument is completely missing the point.

How so?

Nobody can help you if you don't want to install bug fixes, so I won't comment on that further.

I did not say I didn't want to install bugfixes!!

I only said that the (valid!) argument against rolling is that with rolling the updates are likely to introduce regressions and break stuff. But THAT many snapshots provides such shielding against this...that both snapshots AND freezing software versions to avoid regressions seems quite overkillish.

2. Snapshots != backups. If you were to include personal data (your home folder is excluded by default) then restoring a snapshot to restore a previous system state would also restore that same previous state to your personal data. In almost all cases that's not what you'd want.

Solution: While restoring a snapshot, give an option whether i want to (a) restore system files (b) home dir (c) both. If in a very similar way i can be protected against regressions AND HDD failures, then why not?

[gm10]

I only said that the (valid!) argument against rolling is that with rolling the updates are likely to introduce regressions and break stuff. But THAT many snapshots provides such shielding against this...that both snapshots AND freezing software versions to avoid regressions seems quite overkillish.

Still completely besides the point. Regressions are not specific to feature updates. And why are we discussing regressions again?

Solution: While restoring a snapshot, give an option whether i want to (a) restore system files (b) home dir (c) both. If in a very similar way i can be protected against regressions AND HDD failures, then why not?

You asked me a question, I gave you the answer. I'm not the author of that software so arguing what if's with me won't get you anywhere, suggest the feature to the author and see what he says. But as you nicely laid out yourself in your OP, you'd store user data in a different place than a system snapshot, so you already made the case against your own suggestion.

[Hoser Rob]

Your rolling release argument is completely missing the point.

How so? ...

Because you need to learn ore about how rolling releases and Linux works. You want the new versions of software of rolling releases and LTS stability and you can't have both. Snaps etc have potential but aren't the answer.

[ud6]

..something seems overkillish, something seems too much. Either strive to provide as much stability as possible to make snapshots unnecessary... or ship new software...?

Even if we use a 'stable' release, the system can crash. However, I agree that snapshots doesn't seem to be the answer. I and many others have had problems with timeshift (old snapshots not being removed and system thus filling disk and, ironically, crashing computer).

Snapshots best done on removable media (any problems and you can format the disk). But personally I just back up home (on large f2fs formatted SD card, so it is fast amd easy). I try not to tweak Mint too much, so if system crashes I can reinstall if necessary, without major changes. Part of the reason I use Mint is stability.

[rambo919]

Snapshots are not so much backups as insurance against system corruption of whatever kind, something especially needed for noobs or less technical users. Followed less intelligent cli advice with just the wrong command removing important system folders? Changed the permissions or ownership recursively from the wrong directory? Testing a possibly conflicting meta package? Use a snapshot and everything is exactly the way it was before you either accidentally or stupidly screwed up your system.

In my case (in a VM but still) I installed a handful of DE's to see the actual differences in feel and RAM usage... saw what I needed to see and reverted with timeshift. And the whole process was painless and fast without having to even lift the hood nvm go under it. I know timeshift is still not faultless but it's still a good step in the right direction for many and WAY better than M$ system restore in many ways.

Weekly snapshots should be fine for most. What effort is it to make one just before doing something risky the way a system restore point gets made as general rule in windows?

[JerryF]

Snapshots aren't just for restoring updates that come through and have been applied, but very useful for bringing back a system that was tweaked or the removal of an app by the user (rambo919 already alluded to that).

Plus, snapshots use rsync, which is very efficient in using space. After the first original snapshot is created, the subsequent snapshots only contain any changes done from the previous snapshot, thus using little space.

[ajgringo619]

Snapshots aren't just for restoring updates that come through and have been applied, but very useful for bringing back a system that was tweaked or the removal of an app by the user (rambo919 already alluded to that).

Plus, snapshots use rsync, which is very efficient in using space. After the first original snapshot is created, the subsequent snapshots only contain any changes done from the previous snapshot, thus using little space.

+1

Not only that, a restoration is extremely fast. I needed to run one last week after an experiment with a new software version through a PPA didn't go as planned. I was back up and running in less than 3 minutes.

Not 100% convinced about Timeshift's space requirements, though. My / partition is currently sitting at 14.2 GB used. With 5 total snapshots taken, my /snapshots partition is sitting at 30.4 GB used. Why? I have know idea. One thing that I really wish Timeshift had was an easy way to tell exactly how much space each snapshot is actually taking up. Maybe it's high-time I start (re)learning my programming skills and figure this out.

[slipstick]

I keep my TimeShift snapshots (system files only) on my internal HDD in a separate partition so I can restore quickly if an update goes wrong, or if I screw something up. This has saved me a lot of grief on two occasions, one of which was a combined kernel update and Nvidia driver update that messed up my system. These snapshots are scheduled, except for the occasional "on-demand" update that I make just before major updates such as kernel updates or video driver updates. I back up my personal data to a USB drive using Back-In-Time (two copies, each on a separate USB drive). But every couple of days, I also make a copy of my Timeshift snapshots onto one of my USB drives, using a script file:

Code: Select all

#!/bin/bash
#update timeshift backup on external drive from snapshots on internal HD

sudo rsync -aAuHXvis --progress --delete --numeric-ids /media/root/LM18_timeshift/ /media/steve/Z97_LM_Backup/LM18.3_timeshift_backup/timeshift | tee ~/timeshift_backup_log

echo "Finished updating timeshift backup"

sleep 10
exit 0

Note:
You can delete the last part "| ~/timeshift_backup_log" if you want. I put it in just to have a log file to look at, but that file is often large (several hundred MB).

This takes a while to run (10-20 minutes or so, on my PC). It first does all the deletes from the target, then for several minutes there appears to be no activity except for the blinking light on my external HDD, then, finallly, it starts with the additions to the target. So don't panic when it appears to hang up for 10-15 minutes with nothing happening - just wait for it.

As for space used, here is a listing from yesterday's backup on my USB drive - for some reason I couldn't get this "du" listing to work from the internal HDD (see edits), but it should be the same:

Code: Select all

steve@steve-Z97X ~ $ sudo du -shc /media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2*
[sudo] password for steve: 
11G	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-10-01_19-00-02
2.9G	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-01_19-00-01
897M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-11_02-00-01
1.5G	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-18_02-00-01
644M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-20_02-11-25
901M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-22_09-43-41
208M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-24_03-00-01
696M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-25_02-00-01
205M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-25_03-00-01
241M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-26_03-00-01
511M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-27_03-00-01
397M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-28_01-31-10
357M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-28_01-45-25
175M	/media/steve/TS_Backups/LM18.3_timeshift_backup/timeshift/snapshots/2018-11-28_03-00-01
20G	total

ETA: - I'm running LM 18.3.
EDIT: To get the "du" command to work on the TimeShift partition on the HDD, I had to:

Code: Select all

steve@steve-Z97X ~ $ sudo -i
[sudo] password for steve: 
steve-Z97X ~ # du -shc /media/root/LM18_timeshift/timeshift/snapshots/*
11G	/media/root/LM18_timeshift/timeshift/snapshots/2018-10-01_19-00-02
2.9G	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-01_19-00-01
897M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-11_02-00-01
1.5G	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-18_02-00-01
644M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-20_02-11-25
901M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-22_09-43-41
702M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-25_02-00-01
205M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-25_03-00-01
241M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-26_03-00-01
511M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-27_03-00-01
397M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-28_01-31-10
357M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-28_01-45-25
175M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-28_03-00-01
331M	/media/root/LM18_timeshift/timeshift/snapshots/2018-11-29_03-00-04
20G	total
steve-Z97X ~ # exit

EDIT:

Code: Select all

sudo bash -c "du -shc /media/root/LM18_timeshift/timeshift/snapshots/*"

also works - just needed a root shell for filename expansion because /media/root directory has permissions of rwxr-x--- and globbing takes place before "sudo du"

[sdowney717]

I could see a use here if you dont need the hard drive space and it gets you back quicker.
In the past, I have simply reinstalled the OS, wiping out the system partition, I have home on a separate partition.
I suppose it can be restored, say if the system cant boot the desktop? Like a console window? Anyone have a link on the commands to do that?