Best way to take a "snapshot" of a linux system

[Red Squirrel]

Is there a way I can take a "snapshot" of a linux system so I can recover in the event of a disaster? Data itself I got covered but I'm talking about the settings/apps themselves. I don't want to spend 10 days rebuilding everything in the event of a failure. I tried acronis but it does not like that system.

Is backing up /etc /var /usr /boot /bin /sbin sufficient? I probably can't do that on a live system without some files being in use, but if I do it while I'm booting off a live CD, will that work ok when I go to restore it?

 

[xSauronx]

Originally posted by: RedSquirrel
I tried acronis but it does not like that system.

maybe partimage would be useful? partimage

 

[Crusty]

The only thing you should need to backup is /etc if you've got your data backed up. All of your configurations should be in that directory, everything else should be replaceable. Of course if you had to do custom installs for particular libraries it would be a wise idea to have those steps saved somewhere so you can easily redo them. It all depends on what you're doing with the server, but from your past posts it seems like this is a dedicated web hosting server so it doesn't seem like there should be any custom installs.

We keep base images for our servers that have all of the needed software/libraries pre-installed that we use and backup each servers /etc directory to keep all system unique settings saved.

An image is really the fastest way to recover a system, especially if you're running linux with only the bare essentials needed to run your server. Our base image fits on one CD, but pretty soon we are going to start using DVD's.

 

[Onund]

I run a monthly cron job that does this:
tar -cvpzf backup.tgz --exclude=/proc --exclude=/lost+found --exclude=/backup.tgz --exclude=/mnt --exclude=/sys /

I have successfuly used this tar to 'recover' my system on a new HD, more like upgrade the harddrive. This method might require some boot loader work though, I don't recall now what I did. I think I used a live CD to start up the system with my HD, formatted and untared then did some grub work.

Edit:
forgot to say you'll have to mkdir your excluded dirs this way after the untar

 

[Red Squirrel]

I'll try partimage.

I want to avoid having to reinstall any apps in the event of disaster. Just copying /etc would still require to reinstall everything. This is for my home server which has more specialized setups such as vmware which is a task to install due to it needing kernel modules. So would copying the other folders and restoring simply work? (assuming partimage craps out too, which I have a feeling it will).

Think my issue is I have two sata controller cards, so they probably only load up once the OS loads up (ex: acronis booter), then the drive orders get scrambled and it can't finish booting off the cd. That's my guess at least.

 

[sourceninja]

I've had success with the tar route as well. Linux has no problems letting you read files that are in use. If the file is being written to, then you might have some problems, but that is usually a data file, and you can schedule the services for those databases to be shutdown before you backup (for exmaple turn off your mail server, backup, turn it back on).

Then you can just extract the tar file to a new hard drive and install a boot loader.

 

[Nothinman]

You can tar up all of the files while the system is running, the only files that would be problematic is those that get written to while tar is running. So logs, databases, etc could be suspect but binaries, config files, etc are all fine. You could also take a snapshot of the volume to ensure that no writes happen if you're using LVM.

 

[Red Squirrel]

I ended up using the rescue CD but was unable to even boot into any kind of menu where I can pick the tool I want. I got dropped to a shell. I tried to start X to see if it would bring me to some menu but it just froze at the initial screen with the cursor in middle and the mouse did not work. Tried to also start gparted to see if it would load but did not. I could not remember the name of the imaging program as I figured I'd get an option for it.

So I ended up just copying all of / (from the system, not the livecd - without the raid mounted) which was 11GB. I never realized how fast esata was. I copied it to a temp drive on my sata dock and 11GB took about 10 minutes or so. It's compressing to a tar now then I'll keep it in my backups. So in the event of a disaster I should be able to untar that and replace all the files and it will work right? I also made sure to preserve all permissions.

 

[crontab]

i don't image systems at work, but when i need to p2v stuff, i boot off a live cd and dd the whole drive or the partitions to another drive/system.

you can do the same since it seems you have another drive for storage..

 

[Red Squirrel]

well I don't want my disaster recovery image taking up 50 times more space then it needs to. That drive was temporary, it will eventually be thrown as part of my backup rotations once I get my new backup system setup. HDDs and a docking station is way cheaper then tapes and holds more.

On the other hand, if I had raid1 I would essentially be using a whole drive for "backup" and I don't have raid1 on that drive so I suppose it's not truely a waste to just DD the whole thing to another drive. It would be even better than raid as it would be a true backup.