Total noob question about very old snapshot

[marian78]

Hi,

i search for answer for my total noob question.

My situation:
Have two old freenas box (with FN 9.10.2 U3 installed).

In begining, i used replications for backuping data. But after some time i decided use rsync for backup and not replications. I disabled autosnapshot task and disabled replication task.

Time is gone, some beer, some fun,....

Today i again setted new auto snapshot task (every 1 day for 1 week), but for now for protecting data on dataset.

Next i decided, that i will check, if snapshots are generate. But my blind eyes saw some very old snapshots from 2015.

I want ask, it is safe to delete these snapshots without loosing data? If it is safe, how to properly delete these very old snapshots, because today i start again generate new auto-snapshots....

 

[Vito Reiter]

Simply click destroy snapshot under volumes > snapshots. It's safe as long as you have a newer one that you've verified the integrity of. Basically, if you're sure you don't need the old snapshot it is safe to delete.

 

[marian78]

Thx sir for quick reply.

So, if i now create new auto snapshot for "/mnt/volume" recursive, after deleting all old snapshots from 2015, this dont delete data on volume (data from 2014 to 2017)? <--- this is very noob question...

Is there some automated way for deletion (delete all snapshots from year 2015), because i have it over 500...

 

[Vito Reiter]

Snapshots are just the ability to rollback the filesystem, deleting files won't delete them from the snapshot, and deleting a snapshot won't delete the files, just the ability to go back to what you had in 2015. Also, you can set a lifespan on snapshots so they don't last several years like that. I don't know of a way to delete all of them at once though.

 

[marian78]

I'm cautious, because after deleting the snapshots i lost the data from volume. It was on the backup freenas, to which I replicated the data.
It's been a long time ago, probably on version FN9.3.1 ....

 

[Vito Reiter]

Don't think that's how it should work.. I don't want you to lose everything either, but I assume if you deleted a snapshot and the volume lost data, that that data wasn't in the volume anyway just held by the snapshot. Can't help much further than that.

 

[Kevin Horton]

Run zfs list -t snapshot to get a list of all snapshots.

zfs destroy can be used to destroy a range of snapshots, by specifying the first one, and the last one, with a "%" in between. The "-n" flag is used for a dry run, in which case it simply lists the snapshots that would be destroyed.

Example, zfs list -t snapshot shows lines like this:

Code:

backup/plex@auto-20170218.2055-1y										1.22M	  -   514G  -
backup/plex@auto-20170319.0100-1y										1.46M	  -   535G  -
backup/plex@auto-20170416.0100-1y										1.32M	  -   576G  -
backup/plex@auto-20170419.0000-30d									   2.28G	  -   607G  -
backup/plex@auto-20170420.0000-30d									   1.19M	  -   623G  -
backup/plex@auto-20170421.0000-30d									   1.05M	  -   626G  -
backup/plex@auto-20170422.0000-30d									   1.03M	  -   626G  -
backup/plex@auto-20170423.0000-30d									   5.98G	  -   645G  -
backup/plex@auto-20170424.0000-30d									   1.17M	  -   661G  -
backup/plex@auto-20170425.0000-30d									   1.08M	  -   649G  -
backup/plex@auto-20170426.0000-30d									   1.26M	  -   632G  -
backup/plex@auto-20170427.0000-30d									   1.19M	  -   639G  -

If I want to destroy the snapshots in rows 2 through 5, I would run a command like this:

zfs destroy -rvn backup/plex@auto-20170319.0100-1y%auto-20170420.0000-30d

Output:

Code:

would destroy backup/plex@auto-20170319.0100-1y
would destroy backup/plex@auto-20170416.0100-1y
would destroy backup/plex@auto-20170419.0000-30d
would destroy backup/plex@auto-20170420.0000-30d
would reclaim 4.56G

If I really wanted to destroy those snapshots, I would run that command again without the "-n" flag

zfs destroy -rv backup/plex@auto-20170319.0100-1y%auto-20170420.0000-30d

Good luck. I have used the above commands in the past, but no warranty is provided.

 

[Robert Trevellyan]

i have it over 500...

The GUI allows multiple selection of snapshots.

 

[marian78]

Thanks you all for the answers.
I'm still a bit lost in "snapshots" and I'm afraid to erase them. I do not want lost any data.

I guess we'll have to risk it and try some less important dataset.

 

[Robert Trevellyan]

I'm afraid to erase them. I do not want lost any data.

Would it help to say that a snapshot simply records what a dataset looked like at some point in the past? Therefore, if the current state of the dataset includes all the data you want to keep, deleting a snapshot can't possibly do any harm. Conversely, if you think you might want to recover data from a snapshot of a dataset that no longer includes everything you want, deleting that snapshot could be harmful.