Saving root filesystem with tar

Mr. Alex · 01-04-2014, 12:43 AM

Hello guys! I am planning to tar my root partition to temporarily move it to another HDD and later back on the old one and untar, so while it's on a new drive I can do some things with the old one. And I wanted to make sure I won't screw it up. Is this set of option (from LiveCD, in a mounted root directory) enough for tar to save and restore all OS files correctly:

Code:

tar cpf sda1.tar *

Or do I need to add some option to handle links or anything else?

grail · 01-04-2014, 04:04 AM

I think you will need to exclude all temporary file systems (/tmp, /sys, /proc ...)

If you do exclude the above I would suggest placing the tar file on one of them as including within the area being tarred can throw errors (just warnings I think).

As doing the main system you would need to be root, hence -p is already the default

you may also wish to consider compressing it depending on the size of the data and the room on the drive

Mr. Alex · 01-04-2014, 04:43 AM

Quote:

Originally Posted by grail

I think you will need to exclude all temporary file systems (/tmp, /sys, /proc ...)

Will I? As I mentioned, "from LiveCD, in a mounted root directory". So yes, tar file will have to be put somewhere else, but there will be no /proc or /sys dirs/filesystems on sda1 mounted to, say, /mnt when doing it all from some LiveCD. Right?

TobiSGD · 01-04-2014, 07:14 AM

Quote:

Originally Posted by Mr. Alex

Will I? As I mentioned, "from LiveCD, in a mounted root directory". So yes, tar file will have to be put somewhere else, but there will be no /proc or /sys dirs/filesystems on sda1 mounted to, say, /mnt when doing it all from some LiveCD. Right?

Indeed, but you still may to exclude /tmp, unless it is empty anyway.

jpollard · 01-04-2014, 12:02 PM

I use a shell script for backups - even when on line.

Code:

#!/bin/sh
# backup.sh - a simple backup script creating tar files
# usage:
#	backup.sh [ref]
# where:
#	ref	- reference name of filesystem to backup.
# note:
#	If no ref is specified then all file systems will be backed up.
#	Reference names are one (or more) of root, boot, or home;
#	separated by spaces.
#------------------------------------------------------------------------
# configuration
#	Adding filesystems to the Base list requires modifying
#	the evaluation and the list of real filesystems.
#	This script may be redone as a perl script to simplify this...
#------------------------------------------------------------------------

Base="root boot home"
Release="Fedora16"
TARGET="/home/sys"
HOST="panther"

#------------------------------------------------------------------------
# evaluate options

if [ "$*" == "" ]; then
   list="${Base}"
else
   list="$*"
fi

for item in $list; do
    case $item in
	root);;
	boot);;
	home);;
	*)
	   echo "Only one of \"${Base}\" can be used"
	   exit 1 
	;;
    esac
done

#------------------------------------------------------------------------
# perform the backup

DATE=`date +"%Y.%m.%d"`

# protect the generated tar files

umask 077

# verify destination exists

if [ ! -d "${TARGET}/${HOST}" ]; then
    mkdir ${TARGET}/${HOST}
fi

if [ ! -d "${TARGET}/${HOST}/${Release}" ]; then
    mkdir ${TARGET}/${HOST}/${Release}
fi

# backup the list of filesystems

for item in ${list}; do

    echo "${item} -"`date +%H:%M:%S`
    case ${item} in
	root)	frm="/"
		xclude=" --exclude /tmp/* --exclude /var/tmp/* --exclude=/home"
		;;
	boot)	frm="/boot"
		xclude=""
		;;
	home)	frm="/home"
		xclude="";;
    esac 
    tar --one-file-system --selinux --acls --xattrs -z \
	${xclude} \
	-cf \
		${TARGET}/${HOST}/${Release}/${item}.${DATE}.tgz ${frm}

done
echo "done  -"`date +%H:%M:%S`

exit

Tar will identify files that change while it is performing a backup... and normally this is not a problem as the files are the log files...

Using the "--one-file-system" eliminates the need to specifically exclude /proc, /sys, and any mounted filesystem as tar will only create an entry for the mountpoint, but not backup any of the files within.