snapshots, rollbacks and critical information.

Posted by mylinuxguy@reddit | linuxadmin | View on Reddit | 3 comments

I've never used snapshots where you can decide to 'rollback' one if you decided that something broke and you want to go back to a previous version. On the surface.. it seems like a nice thing thing to be able to do. Maybe it's the best thing ever.. but I can see issues. I wanted to see if I am thinking of them incorrectly or not.

Out of the box... it's sort of easy to see why you'd want to have separate / ( or @ ) and /home ( or home ) snapshots. If you upgrade a kernel and find out a few days later that it's bad and want to do a rollback, if /home was not separate, when you did the rollback to fix the kernel issue, you'd wipe out days of user changes.

But when you have a busy server with Mail Directories, Database Directories, Docker Containers, VMs, etc where data is spread all over /var and /etc and maybe /srv and /opt how do you do a snapshot / rollback and not loose critical information?

Are snapshots for 'simple' systems or do people actually figure out which specific dir in /var that can be restored and which ones can't be restored and have complex directory structures or what exactly?

Thinking that maybe snapshots are not something I want... but I can see where it would be nice to have... I can also see me wiping out important data by mistake.

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faxattack@reddit

Rolling back kernel is not harder than simply selecting the earlier one from the boot menu.

420ball-sniffer69@reddit

At my place we take a daily master doomsday backup and copy it over to an LTO tape library. In the snapshot we take records of the slurm database, all configuration files as well as other stuff that we’d need in a doomsday scenario

treuss@reddit

Like you said: snapshots protect you from damages during updates or upgrades. That's why I'd only recommend using them on root filesystem which is separate from home, var, srv and so on.

If you snapshot reset a database you might even end up with data corruption.

If I'm going to make larger changes on a system, I'll create an offline snapshot via VMware and create a database full backup. However, I'd want to have a downtime for this. In my case we're typically talking about SAP S/4 systems or conversions of a classic ECC system on databases like Oracle or DB2 to S/4HANA.