Clone Raspberry Pi SD card to image file

rpi-backup-sd-to-img.txt

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# OBJECTIVE > A GitHub gist attempting to describe how one could backup the 
# ...entirity of a Raspbian OS install to a sparse image file.
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# REQUIREMENTS
# 1) raspberry pi
# 2) SD card
# 3) A seperate computer or SD card to mount the original Raspbian OS
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# SETUP
# 1) Install Raspbian OS to an SD card using preferred method, ie. Etcher or
# ...some other method.
# 2) Install, update, software in Raspbian, make and save some configuration changes
# 3) Power off the Pi, remove the SD card, mount the SD via a card reader,
# ...or mount the SD card on a different computer preferably running Linux, or
# ...or have another SD card that has enough space to backup the entirity of SD
# ...card #1, ie. preferably have a 128GB SD card to backup a 64GB SD.
# NOTE during the initial backup phase 64GB of space will be used on SD card #2
# ...or computer backing up the initial SD card, ie. SD card #1.
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# BACKING UP > creating a sparse image of an entire SD card, ie. 
# ...both the 1) `boot` and the 2) `root` partitions into a single file.
# NOTE the majority of commands will require super user privs via `su` or `sudo`
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# TL;DR Steps to reproudce
# 1) zeros will need to be written to empty space (null bytes) on the partitions
# 2) the large single file containing the zero bytes will need be deleted
# 3) sync the file system changes with the local OS
# 4) unmount the file system(s)
# 5) create a sparse image file of the entire disk containing all partitions
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# Procedure
# NOTE path(s) to disks, partitions, and mnt points will vary
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# mount SD card #1 from SD card #2 or seperate computer, and then write zeros 
# ...to boot partition of SD card #1, NOT the BOOT parition of the active system
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mount -o rw /dev/sdb1 /home/pi/mnt/backup-sd-boot
dd if=/dev/zero of=/home/pi/mnt/backup-sd-boot/zero-file bs=1M
sync
rm /home/pi/mnt/backup-sd-boot/zero-file
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# BACKUP > write zeros to root partition
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mount -o rw /dev/sdb2 /home/ip/mnt/backup-sd-root
dd if=/dev/zero of=/home/pi/backup-sd-root/zero-file bs=32M
sync
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# BACKUP > SPARSE > create sparse image file of SD card #1
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dd if=/dev/sdb \
of=/path/to/ext-file-system/to/hold/sparse/image/backup-sd.img \
bs=512 conv=sparse status=progress
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# RESTORE > restoring from a backed up image, images can be restored using Etcher
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dd if=/path/to/ext-file-system/to/hold/sparse/image/backup-sd.img \
of=/dev/sd[DISK_LETTER] \
bs=32M

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# NOTES
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# running `ls /path/to/backup-sd.img` on backed up image file will report the full
# ...file size of the SD card backed up however `-s` flag will print the actual
# ...block size of the file on disk because the `img` file contains sparse bytes
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# Not all file systems handle sparse files, ie. FAT32, and different filesystems
#...manage sparse files differently making them incompatible when tranferring
#...between file sytems.
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# mount an accessible network partition on a LAN using Raspbian so a local SD 
# ...card can be backed up to an `.img` file.
#
# NOTE I'm mounting a partition on a Apple Time Capsule from Raspbian to 
# ...backup the entire contents of an SD card.
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sudo mount -t cifs \
//[IP_ADDRESS_OF_NFS]/[MNT_POINT] \
/path/to/local/mnt \
-o rw,uid=1000,gid=1000 \
-o iocharset=utf8,sec=ntlm,vers=1.0
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# the below command will backup an entire sd card mounted on a running Raspbian
# ...OS to a network mount point that has been mounted locally from the Raspbian
# ...OS where the local mount point is a partition / file system elsewhere on a LAN.
# NOTE `/dev/sdb` refers to the entire SD card not a single partition
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sudo dd \
if=/dev/sdb \
of=/mnt/net/tc/backup/rpi/backup-01.img \
bs=32M conv=noerror,sync status=progress
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# CREDIT 💳 > https://superuser.com/a/1097391/148584
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# cheers 🍻
# @ipatch