Backup and Recovery Strategies
Backup using dd
dd allows us to take backups of files or entire filesystems and store them as images. It's a powerful tool for creating snapshots that capture the state of a disk at a specific moment.
For this lab, I deleted all the EBS volumes and created a fresh one, /dev/xvdb, then partitioned and formatted it with EXT3, mounting it to /mnt/diskb1. For detailed instructions on disk partitioning and mounting, please refer to sections on Managing partitions.
eden@tst-rhel:mnt $ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/xvda2 10G 2.8G 7.3G 28% /
/dev/xvdb1 9.8G 23M 9.3G 1% /mnt/diskb1
eden@tst-rhel:mnt $ lsblk -f
NAME FSTYPE LABEL UUID MOUNTPOINT
xvda
├─xvda1
└─xvda2 xfs d35fe619-1d06-4ace-9fe3-169baad3e421 /
xvdb
└─xvdb1 ext3 5bae5568-d137-495f-b2f5-e0518b1c6d71 /mnt/diskb1
To backup a filesystem, specify:
if: input file or deviceof: output file or image
Here, we're backing up /dev/xvdb1 to an image file in our home directory:
$ ll
total 0
$ sudo dd if=/dev/xvdb1 of=/home/eden/mybackup.img
[sudo] password for eden:
15215337+0 records in
15215336+0 records out
7790252032 bytes (7.8 GB, 7.3 GiB) copied, 71.3802 s, 109 MB/s
$ ll
total 7607672
-rw-r--r--. 1 root root 7790252032 Dec 7 15:34 mybackup.img
Restore using dd
For this lab, I created another EBS volume, /dev/xvdc, alongside /dev/xvdb which we backed up in the previous step. Both disks have been partitioned, formatted with EXT3, and mounted (/mnt/diskc1 for /dev/xvdc). Refer to earlier sections for disk partitioning and mounting details.
Note: Expanding the root volume from 10G to 50GB is in progress, so I couldn't include the restore output here.
To restore the backup, reverse the process, specifying the backup image as if and the target partition as of:
sudo dd if=/home/eden/mybackup.img of=/dev/xvdc1
Always restore to an unmounted partition (/dev/xvdc1 in this case). This ensures data integrity and prevents conflicts with active filesystem operations.