Csdrhrt

I just received a new workstation and installed RHEL 7 on it, added user accounts, and installed the apps. Before I turn this over to the users I would like to find a way to "image" the disk (user accounts + installed software) so if something happens I can re-create the disk without the hassle of starting from scratch.

I think the Linux dd command will do this for me but, and this is after a lot of on-line reading, it's not a command I understand or feel comfortable using. The workstation's HD is only 2TB, but I have a 30TB networked NAS available.

Here are my questions:

• Is dd the only way to make the image or am I barking up the wrong tree with what I want to do?


• Can I make the image to the NAS or is it DVD only?


• What's the best way to restore the image?

Thanks for your time.

dd is not the only method; an alternate method uses a LiveUSB with Clonezilla. You boot from that LiveUSB to write the image to your NAS; a similar task is illustrated from the Clonezilla help forum.

That Clonezilla file will be much smaller than 2TB as only blocks with content are included in the Clonezilla image, and Clonezilla offers your choice of compression levels to shrink the image even further.

Then, reboot back into your normal configuration, and create another LiveUSB with both Clonezilla and the image file, and duct tape that onto the back of the PC cabinet. If they ever need to restore back to Day Zero, everything they need except you is there, and you can easily walk them through it over the phone while you're on the beach at Diamond Head on your first vacation in years.

If your NAS is mounted, you'll know the mount point where it is mounted. You can dd to a mount point. Boot up a live-dvd. Can you automount the NAS? If so, you know the mountpoint (it'll usually show in your file browser, but if it doesn't, while in the file browser try using the keyboard shortcut Ctrl-l (lower-case L). In a terminal you can look up mount-points with the 'mount' command (just type mount with no options).

Then you can use dd:

dd if=/dev/sda of=/path-to-nas-mointpoint/path-to-desired-directory/backup.img bs=512 conv=noerror,sync

Notice that /dev/sda does not have a number after the 'a'. So it will image the whole disk and not a partition. If there was a partition number then it would image just that partition. You have to use sudo when using dd.
You can check the following webpages for more info:

https://en.wikipedia.org/wiki/Dd_(Unix)

https://www.raspberrypi.org/documentation/installation/installing-images/linux.md

You can check what conv=noerror,sync means by checking the dd man page with man dd.

To restore the image, you just switch around the if= and of= , like

dd if=/path/to/nas/mointpoint/backup.img of=/dev/sda bs=512 conv=noerror,sync

In regards to the bs= option, this page:
https://docs.kali.org/downloading/kali-linux-live-usb-install
says: The recommended value, “bs=512k”, is conservative and reliable.

The raspberrypi.org webpage uses bs=4M . To display progress as dd runs, you can try using status=progress ... if that doesn't work there is another method on those webpages listed.