How to do image backup and restore in centos by using dd

dd
Disk cloning is nothing but a mere process of creating an image of an entire disk. This can be useful for copying disks, backups, recovery and more. The dd command is easy to use tool for making such clones.

dd if=/dev/source of=/mnt/destination bs=64k conv=noerror,sync

bs=64k : Sets the block size to 64k. You can use 128k or any other value.
conv=noerror : Tell dd to continue operation, ignoring all read errors.
sync : Add input blocks with zeroes if there were any read errors, so data offsets stay in sync.

# dd if=/dev/sdc1 of=/dev/sdd1 bs=128K conv=noerror,sync

if you want to put remote place

# dd if=/dev/da0 conv=sync,noerror bs=128K | gzip -c | ssh vivek@server1.cyberciti.biz dd of=centos-core-7.gz

disk image
#dd if=/dev/INPUT/DEVICE-NAME-HERE conv=sync,noerror bs=64K | gzip -c > /path/to/my-disk.image.gz

restore the image
# gunzip -c IMAGE.HERE-GZ | dd of=/dev/OUTPUT/DEVICE-HERE

# gunzip -c centos-core-7.gz | dd of=/dev/da0

if you want to know the status of progress let's add like this
# dd if=/dev/sdc1 of=/dev/sdd1 bs=128K conv=noerror,sync status=progress

-----------------------------------------------------------------------------
[root@ADV-CACTISERVER sdb]# dd if=/dev/sda conv=sync,noerror bs=1024k | gzip -c > /mnt/sdb/centos.gz
30720+0 records in
30720+0 records out
32212254720 bytes (32 GB) copied, 1311.88 s, 24.6 MB/s
---------------------------------------------------------------------------

Add new disk

[root@ADV-CACTISERVER ~]# mkfs.ext4 /dev/sdc

mke2fs 1.41.12 (17-May-2010)

/dev/sdc is entire device, not just one partition!

Proceed anyway? (y,n) y

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

Stride=0 blocks, Stripe width=0 blocks

2293760 inodes, 9175040 blocks

458752 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=4294967296

280 block groups

32768 blocks per group, 32768 fragments per group

8192 inodes per group

Superblock backups stored on blocks:

        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,

        4096000, 7962624

Writing inode tables: done

Creating journal (32768 blocks): done

Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 27 mounts or

180 days, whichever comes first.  Use tune2fs -c or -i to override.

---------------------------------------------------

#gunzip -c /mnt/sdb/centos.gz | dd of=/dev/sdc

it take a while
after that sdb can able to boot