Cloning Production Server for Testing using DAR

Sun, 05/29/2005 - 21:30 — sandip

DAR (Disk ARchive) is a command-line backup tool, that uses compression, makes differential or full backups, which can be split over several files or disks. Dar saves all *NIX inode types, hard links, as well as Extended Attributes. And many other features...

Below are the steps on what was done to get a full archive of an external production server and restore it to a local test machine. The process can also be used for recovering from hard-disk failures.

Installation:

Download and Install:

$ ./configure
$ make
$ su -
# make install-strip

Archive:

Do a full backup of the production server via:
```
# cp `which dar_static` /path/to/archive
# dar -c /path/to/archive/full_server_backup -s 680M -z \
  -R / -P dev/pts -P proc -P path/to/archive -P "home/virtual/site*" \
  -D -m 256 -Z "*.gz" -Z "*.bz2" -Z "*.zip"
```
- -c -- creates a backup with the basename of "full_server_backup"
- -s -- size of slice (680M so the slices fit in CDs)
- -z -- compress slices using gzip alogrithm (default compression level of 6)
- -R -- backup path
- -P -- exclude path
- -D -- store excluded path as empty directories
- -m -- minimum file size for compression
- -Z -- exclude files from compression

Restore:

Use knoppix to boot via CD to prepare, partition and create the filesystems for restoration.

Preparation

Partition the hard-disk as needed:

# fdisk /dev/hda1 ( 100MB for boot)
# fdisk /dev/hda2 ( 256MB for swap )
# fdisk /dev/hda3 ( rest for the system )

Here is the final result:

Disk /dev/hda: 240 heads, 63 sectors, 776 cylinders
Units = cylinders of 15120 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hda1   *         1        14    105808+  83  Linux
/dev/hda2            15        48    257040   82  Linux swap
/dev/hda3            49       776   5503680   83  Linux

Inform the kernel of the new partitions:

# partprobe /dev/hda1 /dev/hda2 /dev/hda3

Filesystems Format

# mke2fs -j /dev/hda1 ( ext3 filesystem )
# mkswap -c /dev/hda2 ( swap )
# mke2fs -j /dev/hda3 ( ext3 filesystem )

Activate Swap
```
# swapon /dev/hda2
```

Mount

# mount -t vfat /dev/sda1 /mnt/sda1 ( external usb storage drive )
# mount -t ext3 /dev/hda3 /mnt/hda3 
# mkdir /mnt/hda3/boot
# mount -t ext3 /dev/hda1 /mnt/hda3/boot

Restore

# cp /mnt/sda1/dar_static /mnt/hda3/
# /mnt/hda3/dar_static -x /mnt/sda1/path/to/full_server_backup -R /mnt/hda3
# rm /mnt/hda3/dar_static

Lilo Check
Once the archive is restored, launch lilo to boot properly.
```
# chroot /mnt/hda3
# lilo -v -v
# exit
```
Reboot
```
# shutdown -r now
```

Comments

Thu, 06/23/2005 - 20:12 — sandip Remote Restore over SSH using DAR

On the localhost where the remote backup is to be restored:

Generate a ssh passwordless login key.
```
$ ssh-keygen -t dsa
```
Note: Press enter when prompted for password.
Copy the "id_dsa.pub" to remote backup server as "authorized_keys2".
```
$ scp ~/.ssh/id_dsa.pub remote_server:./.ssh/authorized_keys2
```
Create the named pipes "todar" and "toslave".
```
$ mkfifo /tmp/todar /tmp/toslave
```

Run the dar_slave on remote and dar_static on local:

$ ssh remote_host dar_slave /path/to/backup </tmp/toslave >/tmp/todar &
$ /path/to/dar_static -x - -i /tmp/todar -o /tmp/toslave /file/to/restore1 /file/to/restore2 ... /file/to/restoreN

Note: Leaving out the file/folder to restore path, will restore everything.

Fri, 06/17/2005 - 10:19 — sandip Remote Backup using DAR over SSH

DAR can output its archive to stdout instead of a given file. To activate it, use "-" as basename.

# ssh remote_host /path/to/dar -c - -z \
  -R / -P dev/pts -P proc -P "path/to/skip*" \
  -D -m 256 -Z "*.gz" -Z "*.bz2" -Z "*.zip" -Z "*.jpg" -Z "*.png" \
  | dar_xform -s 680M - /path/to/full_backup

Tue, 06/14/2005 - 09:51 — sandip Extended Attributes Namespace error

Use the -U and -u option to not consider user and system namespaces.

Sun, 06/12/2005 - 15:04 — sandip libattr.a error when doing make

Note: when installing dar on RHEL3 and Fedora Core 3, I had to symlink as below:

# ln -s /usr/lib/libattr.a /lib/libattr.a

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