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Tar options for bare metal recovery

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There is a lot conflicting information about what options to use for creation of recovery tarball. Here is what Relax-and-Recover uses (relax and recover is just fancy envelope for tar)

# save everything except directories listed in file /exclude_dirs
time tar cvpPzf $TARBALL -C / -X /exclude_dirs / 
If you have everything in one partition you can use option --one-file-system and explicitly exclude pseudo-directories such as /proc /sys
time tar cvpPzf  $TARBALL  -C / --one-file-system  --exclude /mnt --exclude /proc exclude /sys  / 

Where: 

Warning: Exclude actually  specifies not a file path, but a "basic" (DOS style) regular expression for the file(s) or directories.

 Excluding Some Files

To avoid operating on files whose names match a particular pattern, use the `--exclude' or `--exclude-from' options.

`--exclude=pattern'
Causes tar to ignore files that match the pattern.

The `--exclude=pattern' option prevents any file or member whose name matches the shell wildcard (pattern) from being operated on. For example, to create an archive with all the contents of the directory `src' except for files whose names end in `.o', use the command `tar -cf src.tar --exclude='*.o' src'.

You may give multiple `--exclude' options.

`--exclude-from=file'
`-X file'
Causes tar to ignore files that match the patterns listed in file.

Use the `--exclude-from' option to read a list of patterns, one per line, from file; tar will ignore files matching those patterns. Thus if tar is called as `tar -c -X foo .' and the file `foo' contains a single line `*.o', no files whose names end in `.o' will be added to the archive.

Notice, that lines from file are read verbatim. One of the frequent errors is leaving some extra whitespace after a file name, which is difficult to catch using text editors.

However, empty lines are OK.

When archiving directories that are under some version control system (VCS), it is often convenient to read exclusion patterns from this VCS' ignore files (e.g. `.cvsignore', `.gitignore', etc.) The following options provide such possibility:

 
`--exclude-vcs-ignores'
Before archiving a directory, see if it contains any of the following files: `cvsignore', `.gitignore', `.bzrignore', or `.hgignore'. If so, read ignore patterns from these files.

The patterns are treated much as the corresponding VCS would treat them, i.e.:

`.cvsignore'
Contains shell-style globbing patterns that apply only to the directory where this file resides. No comments are allowed in the file. Empty lines are ignored.
`.gitignore'
Contains shell-style globbing patterns. Applies to the directory where `.gitfile' is located and all its subdirectories.

Any line beginning with a `#' is a comment. Backslash escapes the comment character.

`.bzrignore'
Contains shell globbing-patterns and regular expressions (if prefixed with `RE:'(16). Patterns affect the directory and all its subdirectories.

Any line beginning with a `#' is a comment.

`.hgignore'
Contains posix regular expressions(17). The line `syntax: glob' switches to shell globbing patterns. The line `syntax: regexp' switches back. Comments begin with a `#'. Patterns affect the directory and all its subdirectories.
`--exclude-ignore=file'
Before dumping a directory, tar checks if it contains file. If so, exclusion patterns are read from this file. The patterns affect only the directory itself.
`--exclude-ignore-recursive=file'
Same as `--exclude-ignore', except that the patterns read affect both the directory where file resides and all its subdirectories.
 
`--exclude-vcs'
Exclude files and directories used by following version control systems: `CVS', `RCS', `SCCS', `SVN', `Arch', `Bazaar', `Mercurial', and `Darcs'.

As of version 1.29, the following files are excluded:

  • `CVS/', and everything under it
  • `RCS/', and everything under it
  • `SCCS/', and everything under it
  • `.git/', and everything under it
  • `.gitignore'
  • `.gitmodules'
  • `.gitattributes'
  • `.cvsignore'
  • `.svn/', and everything under it
  • `.arch-ids/', and everything under it
  • `{arch}/', and everything under it
  • `=RELEASE-ID'
  • `=meta-update'
  • `=update'
  • `.bzr'
  • `.bzrignore'
  • `.bzrtags'
  • `.hg'
  • `.hgignore'
  • `.hgrags'
  • `_darcs'
`--exclude-backups'
Exclude backup and lock files. This option causes exclusion of files that match the following shell globbing patterns:
.#*
*~
#*#

When creating an archive, the `--exclude-caches' option family causes tar to exclude all directories that contain a cache directory tag. A cache directory tag is a short file with the well-known name `CACHEDIR.TAG' and having a standard header specified in http://www.brynosaurus.com/cachedir/spec.html. Various applications write cache directory tags into directories they use to hold regenerable, non-precious data, so that such data can be more easily excluded from backups.

There are three `exclude-caches' options, each providing a different exclusion semantics:

`--exclude-caches'
Do not archive the contents of the directory, but archive the directory itself and the `CACHEDIR.TAG' file.
`--exclude-caches-under'
Do not archive the contents of the directory, nor the `CACHEDIR.TAG' file, archive only the directory itself.
`--exclude-caches-all'
Omit directories containing `CACHEDIR.TAG' file entirely.

Another option family, `--exclude-tag', provides a generalization of this concept. It takes a single argument, a file name to look for. Any directory that contains this file will be excluded from the dump. Similarly to `exclude-caches', there are three options in this option family:

`--exclude-tag=file'
Do not dump the contents of the directory, but dump the directory itself and the file.
`--exclude-tag-under=file'
Do not dump the contents of the directory, nor the file, archive only the directory itself.
`--exclude-tag-all=file'
Omit directories containing file file entirely.

Multiple `--exclude-tag*' options can be given.

For example, given this directory:

 
$ find dir
dir
dir/blues
dir/jazz
dir/folk
dir/folk/tagfile
dir/folk/sanjuan
dir/folk/trote

The `--exclude-tag' will produce the following:

 
$ tar -cf archive.tar --exclude-tag=tagfile -v dir
dir/
dir/blues
dir/jazz
dir/folk/
tar: dir/folk/: contains a cache directory tag tagfile;
  contents not dumped
dir/folk/tagfile

Both the `dir/folk' directory and its tagfile are preserved in the archive, however the rest of files in this directory are not.

Now, using the `--exclude-tag-under' option will exclude `tagfile' from the dump, while still preserving the directory itself, as shown in this example:

 
$ tar -cf archive.tar --exclude-tag-under=tagfile -v dir
dir/
dir/blues
dir/jazz
dir/folk/
./tar: dir/folk/: contains a cache directory tag tagfile;
  contents not dumped

Finally, using `--exclude-tag-all' omits the `dir/folk' directory entirely:

 
$ tar -cf archive.tar --exclude-tag-all=tagfile -v dir
dir/
dir/blues
dir/jazz
./tar: dir/folk/: contains a cache directory tag tagfile;
  directory not dumped
Problems with Using the exclude Options   

[ < ][ > ]  [ << ][ Up ][ >> ]        [Top][Contents][Index][ ? ]

Problems with Using the exclude Options

Some users find `exclude' options confusing. Here are some common pitfalls:

 

Exclude File

tar has the ability to ignore specified files and directories contained in a special file. the localtion of the file is specified with option -X.  The syntax is one definition per line. tar also has the capability to understand regular expressions (regexps). For example:

# Not old backups                                                              
/opt/backup/arch-full*                                                                  
                                                                               
# Not temporary files                                                          
/tmp/

# Not the cache for pacman
/var/cache/pacman/pkg/

 

see BackupYourSystem-TAR - Community Help Wiki

Backup Script

Success of bare metal recovery using tar archive depends on the correctness of your options. Here is a basic script that can do it and provides a couple checks. You'll need to modify this script to define your backup location, and exclude file (if you have one), and then just run this command after you've chrooted and mounted all your partitions.

#!/bin/bash
# full system backup

# Backup destination
backdest=/opt/backup

# Labels for backup name
#PC=${HOSTNAME}
pc=pavilion
distro=arch
type=full
date=$(date "+%F")
backupfile="$backdest/$distro-$type-$date.tar.gz"

# Exclude file location
prog=${0##*/} # Program name from filename
excdir="/home/<user>/.bin/root/backup"
exclude_file="$excdir/$prog-exc.txt"

# Check if chrooted prompt.
echo -n "First chroot from a LiveCD.  Are you ready to backup? (y/n): "
read executeback

# Check if exclude file exists
if [ ! -f $exclude_file ]; then
  echo -n "No exclude file exists, continue? (y/n): "
  read continue
  if [ $continue == "n" ]; then exit; fi
fi

if [ $executeback = "y" ]; then
  # -p and --xattrs store all permissions and extended attributes.
  # Without both of these, many programs will stop working!
  # It is safe to remove the verbose (-v) flag. If you are using a
  # slow terminal, this can greatly speed up the backup process.
  tar --exclude-from=$exclude_file --xattrs -czpvf $backupfile /
fi

First stage restoration

Run you kickstart file with you ISO disk to get a base system.

Second Stage Restoration

To restore the test computer:

[root@tester ~]# restore.all

If you used tar for your backup and restoration, and used the -k (keep old files, don't overwrite) option, you will see a lot of this:

tar: usr/sbin/rpcinfo: Could not create file:  File exists
tar: usr/sbin/zdump: Could not create file:  File exists
tar: usr/sbin/zic: Could not create file:  File exists
tar: usr/sbin/ab: Could not create file:  File exists
This is normal, as tar is refusing to overwrite files you restored during the first stage of restoration.

Just to be paranoid, run LILO after you perform your restoration. I doubt it is necessary, but if it is necessary, it's a lot easier than the alternative. You will notice I have it in my script, restore.all (see Listing 3).

Listing 3. restore.all Script

Now reboot. On the way down, you will see a lot of error messages, such as "no such pid." This is a normal part of the process. The shutdown code is using the pid files from dæmons that were running when the backup was made to shut down dæmons that were not started on the last boot. Of course there's no such pid.

Your system should come up normally, with a lot fewer errors than it had before. The acid test of how well your restore works on an RPM based system is to verify all packages:

rpm -Va

Some files, such as configuration and log files, will have changed in the normal course of things, and you should be able to mentally filter those out of the report.

If you took my advice earlier and keep RPM metadata as a normal part of your backup process, you should be able to diff the two files, thereby speeding up this step considerably.

You should be up and running. It is time to test your applications, especially those that run as dæmons. The more sophisticated the application, the more testing you may need to do. If you have remote users, disable them from using the system, or make it "read only" while you test it. This is especially important for databases, to prevent making any corruption or data loss worse than it already might be.

If you normally boot to X, and disabled it above, test X before you re-enable it. Re-enable it by changing that one line in /etc/inittab back to: id:5:initdefault:

You should now be ready to rock and roll-and for some Aspirin and a couch.

Tips

SanDisk FIT USB drives can be as large as 128 GB.

"FIT" form factor almost does not protrude from the USB port. There is a small (orange in case of SanDisk) indicator light and I kind of like it. When it is writing or reading, the light will blink. They are supposed to be plugged in and seldom pulled out, or pulled out fairly rarely. Perfect for local backup of OS.
Bar form factor protrude one inch or so. Which in many case is acceptable but still carry some risks.

USB 3.0 FIT

USB 3.0 BAR

USB 2.0


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Old News ;-)

[Apr 29, 2018] How not to do system bare-metal backup with tar

He excluded /dev. This is a mistake if we are talking about bare metal recovery.
Apr 29, 2018 | serverfault.com

The backup is made with Tar. I backup the whole system into the Tar file.

If the HDD on my webserver dies, I got all my backups in a safe place.

But what would be the best way to do a Bare Metal Restore on a new HDD with a differential backup make the previous day? Can I boot with a boot cd, and then format a new HDD and untar the backup file into it? How do I do that exactly?

EDIT:

This is my backup script:

#!/bin/sh
# Backup script

BACKUPDIR="/backups"
BACKUPFILE=$BACKUPDIR/backup_$(date +%y-%m-%d).tgz

if [ ! -d $BACKUPDIR ]; then
        mkdir $BACKUPDIR
fi

if [ -f $BACKUPFILE ]; then
        echo "Backup file already exists and will be replaced."
        rm $BACKUPFILE
fi

apt-get clean

tar czpf $BACKUPFILE --same-owner \
--exclude=$BACKUPDIR \
--exclude=/boot/grub/menu.lst* \
--exclude=/home/error.log \
--exclude=/proc \
--exclude=/media \
--exclude=/dev/* \
--exclude=/mnt \
--exclude=/sys/* \
--exclude=/cdrom \
--exclude=/lost+found \
--exclude=/var/cache/* \
--exclude=/tmp / 2>/home/error.log
linux backup debian tar share improve this question edited Dec 22 '11 at 13:25 asked Dec 22 '11 at 3:44 Jonathan Rioux 1,087 4 22 47 add a comment 4 Answers active oldest votes up vote 3 down vote accepted Simply restoring the HDD will not be enough, you're probably will want your boot record too which I hardly believe exists in your backup (am I wrong?, it's better for you if i do!)...

Lest assume you got the server to the point it can boot (i personally prefer creating the additional partition mounted to /boot which will have kernel and initrd with busybox or something similar to allow you basic maintenance tasks). You can also use a live CD of your Linux distribution.

Mount your future root partition somewhere and restore your backup.

tar was created for tapes so it support appending to archive files with same name. If you used this method just untar -xvpf backup.tar -C /mnt if not you'll need to restore "last sunday" backup and applying deferential parts up to needed day.

You should keep in mind that there is a lot of stuff that you should not backup, things like: /proc , /dev , /sys , /media , /mnt (and probably some more which depend on your needs). You'll need to take care of it before creating backup, or it may became severe pain while in restore process!

There is many points that you can easily miss with that backup method for whole server:

Some good points on that exact method can be found on Ubuntu Wiki:BackupYourSystem/TAR . Look for Restoring.

BTW:

P.P.S

I recommend reading couple of Jeff Atwood posts about backups http://www.codinghorror.com/blog/2008/01/whats-your-backup-strategy.html and http://www.codinghorror.com/blog/2009/12/international-backup-awareness-day.html

[Apr 29, 2018] Bare-metal server restore using tar by Keith Winston

The idea of restoring only selected directories after creating "skeleton" linux OS from Red Hat DVD is viable. But this is not optimal bare matalrestore method with tar
Apr 29, 2018 | www.linux.com

... ... ...

The backup tape from the previous night was still on site (our off-site rotations happen once a week). Once I restored the filelist.txt file, I browsed through the list to determine the order that the directories were written to the tape. Then, I placed that list in this restore script:

#!/bin/sh

# Restore everything
# This script restores all system files from tape.
#
# Initialize the tape drive
if /bin/mt -f "/dev/nst0" tell > /dev/null 2>&1
then
    # Rewind before restore
    /bin/mt -f "/dev/nst0" rewind > /dev/null 2>&1
else
    echo "Restore aborted: No tape loaded"
    exit 1
fi

# Do restore
# The directory order must match the order on the tape.
#
/bin/tar --extract --verbose --preserve --file=/dev/nst0 var etc root usr lib boot bin home sbin backup

# note: in many cases, these directories don't need to be restored:
# initrd opt misc tmp mnt

# Rewind tape when done
/bin/mt -f "/dev/nst0" rewind

In the script, the list of directories to restore is passed as parameters to tar. Just as in the backup script, it is important to use the
--preserve switch so that file permissions are restored to the way they were before the backup. I could have just restored the / directory, but
there were a couple of directories I wanted to exclude, so I decided to be explicit about what to restore. If you want to use this script for your own restores, be sure the list of directories matches the order they were backed up on your system.

Although it is listed in the restore script, I removed the /boot directory from my restore, because I suspected my file system problem was related to a kernel upgrade I had done three days earlier. By not restoring the /boot directory, the system would continue to use the stock kernel that shipped on the CDs until I upgraded it. I also wanted to exclude the /tmp directory and a few other directories that I knew were not important.

The restore ran for a long time, but uneventfully. Finally, I rebooted the system, reloaded the MySQL databases from the dumps, and the system was fully restored and working perfectly. Just over four hours elapsed from total meltdown to complete restore. I probably could trim at least an hour off that time if I had to do it a second time.

Postmortem

I filed a bug report with Red Hat Bugzilla , but I could only provide log files from the day before the crash. All core files and logs from the day of the crash were lost when I tried to repair the file system. I exchanged posts with a Red Hat engineer, but we were not able to nail down the cause. I suspect the problem was either in the RAID driver code or ext3 code. I should note that the server is a relatively new HP ProLiant server with an Intel hyperthreaded Pentium 4 processor. Because the Linux kernel sees a hyperthreaded processor as a dual processor, I was using an SMP kernel when the problem arose. I reasoned that I might squeeze a few percentage points of performance out of the SMP kernel. This bug may only manifest when running on a hyperthreaded processor in SMP mode. I don't have a spare server to try to recreate it.

After the restore, I went back to the uniprocessor kernel and have not yet patched it back up to the level it had been. Happily, the ext3 error has not returned. I scan the logs every day, but it has been well over a month since the restore and there are still no signs of trouble. I am looking forward to my next full restore -- hopefully not until sometime in 2013.

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