Re: [gentoo-user] tar a brand new Gentoo install to a USB drive for safe keeping?

[Jil Larner]

Hi Mark,

Mark Knecht a écrit :
> [...]
> happen I have a way to restore where I am today. Since the disk usage
> is currently about 4GB it seems like a great time to do it. Is this
> possible? I think it's essentially what the stage 3 file is that I use
> when I install, isn't it?

If you don't export stage3 and /usr/portage/ files, your backup will be 
lighter. The portage tree shouldn't be backed up because it shall be 
outdated when you'll restore, and emerge --sync will bring it back 
(except if you plan to restore in two weeks and have a low speed 
connection so you use emerge-delta-webrsync, but in that case you 
already know why you need to keep the tree).
For stage3, you can safely discard it.

Cf. exclude-dires in man tar

>
>>From the running system here's what things look like right now:
>
> laptop1 ~ # df
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/sda5             15820524   3641240  11375636  25% /
> udev                     10240       172     10068   2% /dev
> /dev/sda6              1320272    189304   1063900  16% /var
> /dev/sda7             10278304    312012   9444184   4% /home
> shm                    1003844         0   1003844   0% /dev/shm
> laptop1 ~ #
>

Tip: use df -h and put it as an alias (alias df='df -h' in .bashrc) ;)

> My thought is to boot using the install CD, mount a USB drive at
> /mnt/gentoo, then create a mount point 'backup' on the USB drive to
> mount each of the 3 partitions I want to back up one at a time. ( /,
> /var and /home) Then I'll mount each partition by itself and use tar
> to create a single file for each partition where that file gets
> written on the USB drive. When I'm done I have 3 files.

Thus, you would be able to restore only one partition if needed, and 
there is less chance that all your archive becomes corrupted. I would 
process the same way.

You also ought to backup the full MBR, which is a good practice, so you 
can bring back your boot sector and the partition table. Backing it up 
if very painless, just a dd command, cf. http://gentoo-wiki.com/MBR . 
And it saves a *lot* of time when restoring (especially when there is 
@&$#! vista partitions with more sectors than there is really on the 
disk...)

>
> Restore would be to create the partitions anew, untar, install grub
> from in the chroot, and reboot.

So, restore would be a dd command for the MBR, and a mkfs on your 
partitions, then untar your backups. So you wouldn't even need to chroot


>
> Is this a reasonable way to go? Is there something easier? (That seems
> pretty easy to me...)

It is reasonable, for one single computer. If you've more to manage, 
look at dedicated software, or more complex solution as in 
http://gentoo-wiki.com/HOWTO_Backup

>
> I don't want to create images of the partitions because I might want
> to put the data onto a different drive or in a different
> configuration. (Like no /var or something.)

With a separate backup of the MBR, you're free to restore it or not ;) 
But if you want to be able to adjust your partition tables, leave free 
space on the drive and take a look at LVM, very powerful and easy to use 
by now (there's a good tutorial on howtoforge with a debian VMWare 
virtual machine)

>
> If this makes sense then what commands would I want to use to do this
> correctly. Presumably it needs to tar up links, file system
> permissions, and everything else. Since the Quick Install guide uses

You *must* keep permissions of your files, so if you use tar, use -p 
option (cf. man), as if you use cp, use -p option.


> Or is there more to it?

Yep, that's it. Restore mbr, mkfs, mount, untar, sync(or umount), reboot

>
> I'm rambling here so I'll hope for a quick answer and then give it a try.
>
> Thanks in advance,
> Mark
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