OpenWRT and Bare Metal BackUps: Difference between revisions

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The overall objective, long term objective of this project is to create a bare metal backup and move an x86_64 SquashFS based system to an LVM EXT4 based system. The "Backing Up" or BackUp Process or Cloning is of course the first part of that objective.

For this article, the x86_64 (referred to as just x86 in this article) version of OpenWRT on an EXT 4 installed on a BIOS / MBR / DOS partitioned Disk / SSD will be the main focus. SquashFS will be addressed too. All of the below information was tested on an OpenWRT 19.07.10 EXT4 "Combined" (as in MBR, GRUB, Boot, and Root Partition (no Overlay)) based system.

The ~~overall~~ objective ~~beyond~~ a bare metal ~~backup is~~ to ~~eventually move an x86_64~~ SquashFS ~~based system~~ to an LVM ~~EXT4 based system~~.

So why not just use something like an external drive bay to clone the disk / SSD to another drive? Because that involves removing the drive. The end objective is to be able to do a live, bare metal cloning process. Plus it doesn't do anything to accomplish migrating a SquashFS install to an EXT4 install on an LVM drive.

===Backing Up===

The "Backing Up" or BackUp Process is the first part of cloning a system too. So why not just use something like an external drive bay to clone the disk / SSD to another drive? Because that involves removing the drive. The end objective is to be able to do a live, bare metal cloning process.

====Assumptions====

In syntax examples, devices are assumed to be in /dev.

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Bad news. The delete command doesn't always work. After issuing the command on a legitimate Loop Device, and with no errors, the Loop Device will persist. Checking it with LOSETUP -a shows it is still there. Accessing it with CFDISK or MOUNT still works. Oh, well. Windows solution time. Reboot.

==== Example Uses for LOSETUP ====

====Example Uses for LOSETUP====

* Syntax: losetup -o OFFSET_IN_BYTES /dev/loopX /path/to/your/file

*Syntax: losetup -o OFFSET_IN_BYTES /dev/loopX /path/to/your/file

* Example: losetup -o 3014656 -fP /mnt/sda1/OpenWRT_SDC2.img (this command allows for the LOSETUP command to select the next available LOOP Device in /dev)

*Example: losetup -o 3014656 -fP /mnt/sda1/OpenWRT_SDC2.img (this command allows for the LOSETUP command to select the next available LOOP Device in /dev)

* Mount the resulting LOOP Device created by LOSETUP: mount -t f2fs /dev/loop1 /mnt/loop1

*Mount the resulting LOOP Device created by LOSETUP: mount -t f2fs /dev/loop1 /mnt/loop1

* Displays LOOP Devices: losetup -a

*Displays LOOP Devices: losetup -a

* Delete LOOP Devices: losetup -d /dev/loopX

*Delete LOOP Devices: losetup -d /dev/loopX

===FAQs===

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OpenWRT specifically mentions GRUB 2 in their documentation. But the way it works on an x86_64 EXT4 installation of OpenWRT would convince anyone that it is Legacy GRUB (except for the GNU GRUB version 2.02 heading at the top of the screen). The way it is configured via /etc/grub/grub.cfg would also convince anyone that Legacy GRUB was being used. So, the conclusion is that GRUB 2.02 is indeed being used, but since it is backwards compatible, it is in 'Legacy Mode'.

==== QEMU ( QEMU-NDB ) ====

====QEMU ( QEMU-NDB )====

[[wikipedia:QEMU|QEMU]], specifically QEMU-NDB and QEMU-IMG, were commands available to install on OpenWRT that seemed like it would be useful in terms of VHD and other Virtual Disk Files, but were ultimately not needed.

@@ Line 1: / Line 1: @@
+The overall objective, long term objective of this project is to create a bare metal backup and move an x86_64 SquashFS based system to an LVM EXT4 based system.  The "Backing Up" or BackUp Process or Cloning is of course the first part of that objective.
 For this article, the x86_64 (referred to as just x86 in this article) version of OpenWRT on an EXT 4 installed on a BIOS / MBR / DOS partitioned Disk / SSD will be the main focus.  SquashFS will be addressed too.  All of the below information was tested on an OpenWRT 19.07.10 EXT4 "Combined" (as in  MBR, GRUB, Boot, and Root Partition (no Overlay)) based system.
-The overall objective beyond a bare metal backup is to eventually move an x86_64 SquashFS based system to an LVM EXT4 based system.
+So why not just use something like an external drive bay to clone the disk / SSD to another drive?  Because that involves removing the drive.  The end objective is to be able to do a live, bare metal cloning process.  Plus it doesn't do anything to accomplish migrating a SquashFS install to an EXT4 install on an LVM drive.
 ===Backing Up===
-The "Backing Up" or BackUp Process is the first part of cloning a system too.  So why not just use something like an external drive bay to clone the disk / SSD to another drive?  Because that involves removing the drive.  The end objective is to be able to do a live, bare metal cloning process.
 ====Assumptions====
 In syntax examples, devices are assumed to be in /dev.
@@ Line 161: / Line 161: @@
 Bad news. The delete command doesn't always work. After issuing the command on a legitimate Loop Device, and with no errors, the Loop Device will persist. Checking it with LOSETUP -a shows it is still there. Accessing it with CFDISK or MOUNT still works. Oh, well. Windows solution time. Reboot.
-==== Example Uses for LOSETUP ====
+====Example Uses for LOSETUP====
-* Syntax: losetup -o OFFSET_IN_BYTES /dev/loopX /path/to/your/file
+*Syntax: losetup -o OFFSET_IN_BYTES /dev/loopX /path/to/your/file
-* Example: losetup -o 3014656 -fP /mnt/sda1/OpenWRT_SDC2.img (this command allows for the LOSETUP command to select the next available LOOP Device in /dev)
+*Example: losetup -o 3014656 -fP /mnt/sda1/OpenWRT_SDC2.img (this command allows for the LOSETUP command to select the next available LOOP Device in /dev)
-* Mount the resulting LOOP Device created by LOSETUP: mount -t f2fs /dev/loop1 /mnt/loop1
+*Mount the resulting LOOP Device created by LOSETUP: mount -t f2fs /dev/loop1 /mnt/loop1
-* Displays LOOP Devices: losetup -a
+*Displays LOOP Devices: losetup -a
-* Delete LOOP Devices: losetup -d /dev/loopX
+*Delete LOOP Devices: losetup -d /dev/loopX
 ===FAQs===
@@ Line 191: / Line 191: @@
 OpenWRT specifically mentions GRUB 2 in their documentation.  But the way it works on an x86_64 EXT4 installation of OpenWRT would convince anyone that it is Legacy GRUB (except for the GNU GRUB   version 2.02 heading at the top of the screen).  The way it is configured via /etc/grub/grub.cfg would also convince anyone that Legacy GRUB was being used.  So, the conclusion is that GRUB 2.02 is indeed being used, but since it is backwards compatible, it is in 'Legacy Mode'.
-==== QEMU ( QEMU-NDB ) ====
+====QEMU ( QEMU-NDB )====
 [[wikipedia:QEMU|QEMU]], specifically QEMU-NDB and QEMU-IMG, were commands available to install on OpenWRT that seemed like it would be useful in terms of VHD and other Virtual Disk Files, but were ultimately not needed.