Snapshots: Delete, merge, set actual state..?!?!?

[smartysmart34]

Guys, I am sort of confused when it comes to Snapshots and I currently do not have a System to just test it. Maybe one can help:

I understand, taht I can create different snapshots for a system. Lets say,
- one yesterday
- one today
- one tomorrow.

If I start the machine after creation of the tomorrow snapshot i have a new curret state as well.

Now I would expect three choices:
- Return current state to yesterday.
Current state will be yesterdays snapshot. I can start the vm from there, generating a new current state starting yesterday. I can even make a new snapshot from there. This will be on the same level as todays snapshot (tree view)
But todays snapshot and tomorrows will still be there in a parallel tree

- How do I
Merge tomorrows snapshot into todays to get rid of the last snapshot? So that I only have todays snapshot and nothing afterwards?
How do I then merge todays snapshot into yesterdays or maybe get rid of the whole snapshot branch and merge all changes into the main vdi?


- How do i
delete todays snapshot and tomorrows snapshot and only keep yesterdays snapshot without anything being merged?
And without todays and tomorrows snapshot requiring disk space? Really delete them?!

Regards,
Martin

[mpack]

Please read the manual, chapter 1, section 8, "Snapshots". IMHO the concepts are described quite clearly if you dismiss your preconceptions, for example the nonsensical "merge" expectation.

[smartysmart34]

I read the chapter, it is everything but selfexplanatory and I don't get the point of merge being unneccesary. Why?

The chapter does not clearly answer this:

If i have 3 consecutive Snapshots
SS1 -> SS2 -> SS3 -> Current state

If I delete the 3rd. What happens to that information? Where does it go? Will it be deleted? So the updates between 2 and 3 are lost? Or will they be forwarded into the current state?
If I then delete SS1 and 2: What happens to that info? Forwarded to current state? Merged into the VDI?

What if I have two branches?

ss1 -> ss2 -> ss3 -> Current state
-> ss4

If I delete ss4, where does the information go? deleted?

To me the chapter does not answer a single question. Maybe I'm stupid but i would appreciate some help.
Regards,
Martin

[mpack]

I read the chapter, it is everything but selfexplanatory and I don't get the point of merge being unneccesary.

Because you can't merge snapshots. A "snapshot" is a informal term literally meaning a quickly taken photograph. The photograph analogy is used because a photograph represents a frozen instant of time. But how do you merge two photographs?

You can however delete a middle photograph from your album without disturbing the other photographs on either side. You can thumb though your photographs and select the one you will be actively viewing.

If you read the manual with only the above operations in mind, the manual is quite clear. Your problem is that you come to it with a preconception of how these features are implemented, and expect to see those implementation details exposed by the GUI. In fact the implementation details should be irrelevant to you.

On the plus side, no sane person should be using snapshots anyway. You should find that cloning is both safer and easier to understand. It also uses less disk space in the long run.

[smartysmart34]

Unfortunately you seem to have understood snapshots, but are not able or willing to help answer my specific questions in the given example. Because if I delete a middle snaphot out of a chain, the delta information of that snapshot needs to go somewhere. Otherwise the following snapshots would be corrupt. So is it a merge forward into the later snapshot?
What do I do if I want to get rid of all the old snapshots and only continue with the current state? Does this free up some diskspace?
What do I do in the other case: I want to get rid of all snapshots and continue with the status I had right BEFORE the first snapshot?
Any difference in usage and process to achieve this?
Sorry, but you may repeat it for some more times - the manual does not explicitly answer these questions. I doubt you can. At least you haven't until now.

Well, to my understanding: Cloning and using multiple VMs requires multiple licences for commercial OS. Snapshoting doesn't. So up to now, cloning is not an option for me.

Regards,
Martin

[mpack]

Because if I delete a middle snaphot out of a chain, the delta information...

Chain? Delta? Which parts of a photograph do those terms refer to? I point out your reliance on implementation assumptions and yet you persist in doing it. I suggest that you give more thought to this before replying again.

the delta information of that snapshot needs to go somewhere.

It sure does, but that's an implementation detail which a dev needs to care about, not a user. If you really want to know about it then the source code will answer all your questions, at least for the current release (implementation details are not guaranteed to remain the same forever).

What I'm saying is that your confusion is self inflicted. The feature itself is quite simple and quite well explained by the manual.

[smartysmart34]

Then why can't you answer these two simple questions?
To make this clear: I am not interested in technical details. Just: Where do I have to klick when? For case 1) and 2)

1) What do I do if I want to get rid of all the old snapshots and only continue with the current state? (Keep all changes)
1a) Does this free up some diskspace?

2)How do I get rid of all snapshots and continue with the status I had right BEFORE the first snapshot? (Loose all changes)

To me the manual is stil not clear on that.

My problem:
- I have a VM for which I created 4 Snapshots
- The original VDI was 10 GB in size
Each single Snapshot (differential image) gained up to 8 GB
So in total the VDI plus all the delta-Info grew up to 42 GB in total which is way too much.
So I would now prefer to
- stay where I am (keep all changes)
- get rid of all the differencial files and only move on with the vdi

Can you describe what I have to do now?

It simply confuses me to not be able to decide if i want to
- Delete a snapshot and keep the changes (I don't need that point in time anymore because I don't want to go back there)
- Delete a snapshot and loose the changes (I Don't need that snapshot anymore because it was the completely wrong way and i start from somewhere else)
In both cases I want to do this to free up some diskspace and simplify handling of open files for my Host-OS. Doesn't make sense to read through a source VDI plus x differencials just to operate on the virtual disk. Call it housekeeping with snapshots.
Maybe the distinction is hidden somewhere but then it is not obvious.

[mpack]

1) What do I do if I want to get rid of all the old snapshots and only continue with the current state? (Keep all changes).
1a) Does this free up some diskspace?

Isn't the answer obvious by now? You delete the old snapshots. To quote from the manual that you insist on ignoring, "You can also delete a snapshot, which will not affect the state of the virtual machine, but only release the files on disk that VirtualBox used to store the snapshot data, thus freeing disk space". In other words, if you delete a snapshot, then disk space is released without affecting the current state.

2)How do I get rid of all snapshots and continue with the status I had right BEFORE the first snapshot? (Loose all changes)

You can revert to previous snapshot, but you obviously can't revert to a time BEFORE your first snapshot, short of creating a new VM.

But, consider what might happen if you revert to an old snapshot and then delete snapshots from after the current state.

[smartysmart34]

OK so... as long as I delete snapshots from BEFORE my current state the information of this snapshot is "moved forward" so that i don't actually loose anything.
And if I delete snapshots from AFTER my current state then this information is
- "moved forward" as long as there are further snapshots from later dates
- deleted if it was the last snapshot.

Did I get that right?

So if I want to "Delete and keep" I simply delete everything BEFORE my current state.
If I want to "Delete and go back" I first set the current state to the first (root) snapshot and delete every snapshot after that?

I hope I got it and i still think from an enduser point of view this could be made more explicit in the manual. But maybe that's only me.

Anyway: Thank you for your patience.

regards,
Martin

[mpack]

Anyway: Thank you for your patience.

Even I don't think I displayed much patience in this thread. Readers should understand that this issue has been raised and answered about a zillion times. That gets tiresome after a while.

[smartysmart34]

Let's put it that way:
If it has been asked a zillion times, then the GUI was not too easy to understand, right?
Cheers,
Martin

[mpack]

No, I believe I've made clear by now that the feature is quite easy to understand. I was able to explain it to you in a few paragraphs which essentially (or sometimes literally) repeated what the manual says. But if people come to it invalid expectations, and refuse to read the manual or shed those expectations when they have done so... well then nothing much can be done to fix that.

[lurix]

Hello,
here's my story to support the original request for a "merge concept".
0) suppose you accidentally hit "take snapshot" instead of a "save machine state"
1) the system will freeze the image disk, and will start logging all changes to another disk image, the "Differential" one.
2) now suppose that many months later you realize that your guest is performing very bad, that too much disk space is used by two images almost equal in size in place of one, and that what you di is not what you intended to do. So you don't need the saved "state" anymore, but just the current state, and you just want to have ONE SINGLE VDI only, as it was before,
3) What would you do?
a) I go into Virtual Media Manager: my "main disk" is marked as Normal, and "Not Connected", and right clicking on it provides me with no significant choice (just assuming that I don't want to "Remove" it, at least).
b) the child is marked as Differential and bound to my VM, and right-clicking on it provides a "Release" option. Is it the way to go?

Can I go back to the previous situation where I just had one image, and everything was working better?
If you don't call it "merging" the differential disk into its starting disk, How do you call this operation? Deleting?
Can it be done via the GUI; Or should I use the command line?

Thank you!