Getting Old
Recently I've found myself lying awake at night worrying if my documents, code and photos are backed up and recoverable. Or to put it another way - I've officially become old :-(
With a new Raspberry Pi 4B on order it's time to re-purpose the old Raspberry Pi 3B to create a backup solution.
Hardware
I want my backup solution and backup media to be small, cheap and redundant. Speed isn't really an issue, so I've chosen micro SD as my backup media for this project.
I've picked up an Anker 4-Port USB hub, 2 SanDisk 64 GB micro SD cards and 2 SanDisk MobileMate micro SD card readers. I ordered this kit from Amazon and the prices at the time of writing were:
| Component | Price |
|---|---|
| Anker 4-Port USB 3.0 Ultra Slim Data Hub | £10.99 |
| SanDisk Ultra 64 GB microSDXC | £11.73 |
| SanDisk MobileMate USB 3.0 Reader | £7.50 |
They fit together really well, with room for two more SD cards and readers if I need to expand:
The plan is to make one of the SD cards available over the network as a share, via the Pi using SAMBA. The share can be mapped as a Windows network drive and files can easily be dragged and dropped for backup. In case the first backup SD card fails, the Pi will copy the files and folders from the first SD card to the second SD card using rsync to create a backup of the backup.
Software
Download and upgrade the Pi 3B to the lastest version of Raspbian. I've chosen Rapbian Lite to save a bit of space on the Pi's SD card:
https://downloads.raspberrypi.org/raspbian_lite_latest
At the time of writing the lastest download was:
2019-06-20-raspbian-buster-lite.zip
Write the OS to the Pi's SD card using Etcher. Top tip - Etcher can write a .zip file, but it's much quicker to extract the .iso file from the .zip file and write that instead.
Don't forget to add an empty ssh file to the boot partition on the Pi's SD card if you are going to run the Pi headless.
Put the Pi's SD card into the Pi, attached the USB hub and micro SD cards, and boot the Pi and login via SSH. Update and upgrade any new packages first, enable unattended security updates and install your editor of choice:
$ sudo apt-get update $ sudo apt-get upgrade $ sudo apt-get install unattended-upgrades $ sudo apt-get install vim
Because I've got a Pi 4 on the way, I want to call this Pi 'raspberrypi3'. Modify the /etc/hostname and /etc/hosts files:
$ sudo vim /etc/hostname raspberrypi3
$ sudo vim /etc/hosts 127.0.1.1 raspberrypi3
$ sudo reboot
At this point, the backup SD cards should be available to Linux as devices /dev/sda and /dev/sdb.
I want the backup SD cards to be readable on Linux and Windows machines using the exFAT file system. A good tutorial on how to do this on Linux using FUSE and gdisk is available here:
https://matthew.komputerwiz.net/2015/12/13/formatting-universal-drive.html
$ sudo apt-get install exfat-fuse exfat-utils $ sudo apt-get install gdisk
Use gdisk to remove any existing partitions, create a new partition and write this to the SD cards. Make sure to create the new partition as type 0700 (Microsoft basic data) when prompted:
$ sudo gdisk /dev/sda GPT fdisk (gdisk) version 0.8.8 Partition table scan: MBR: not present BSD: not present APM: not present GPT: not present Creating new GPT entries. Command (? for help):
Command (? for help): o This option deletes all partitions and creates a new protective MBR. Proceed? (Y/N): Y
Command (? for help): n
Partition number (1-128, default 1):
First sector (34-16326462, default = 2048) or {+-}size{KMGTP}:
Last sector (2048-16326462, default = 16326462) or {+-}size{KMGTP}:
Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300): 0700
Changed type of partition to 'Microsoft basic data'
Command (? for help): w Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING PARTITIONS!! Do you want to proceed? (Y/N): Y OK; writing new GUID partition table (GPT) to /dev/sda. Warning: The kernel is still using the old partition table. The new table will be used at the next reboot. The operation has completed successfully.
Repeat for the second SD card:
$ sudo gdisk /dev/sdb
Create exFAT partitions on both SD cards and label the partitions PRIMARY and SECONDARY:
$ sudo mkfs.exfat /dev/sda1 $ sudo exfatlabel /dev/sda1 PRIMARY
$ sudo mkfs.exfat /dev/sdb1 $ sudo exfatlabel /dev/sdb1 SECONDARY
Create directories to mount the new partitions on:
$ sudo mkdir -p /media/usb/backup/primary $ sudo mkdir -p /media/usb/backup/secondary
Modify /etc/fstab to mount the SD cards by partition label. This allows us to mount the correct card regardless of it's device path or UUID:
$ sudo vim /etc/fstab LABEL=PRIMARY /media/usb/backup/primary exfat defaults 0 0 LABEL=SECONDARY /media/usb/backup/secondary exfat defaults 0 0
Mount the SD cards:
$ sudo mount /media/usb/backup/primary $ sudo mount /media/usb/backup/secondary
Create a cron job to rsync files from the primary card to the secondary card. The following entry syncs the files every day at 4am:
$ sudo crontab -e 0 4 * * * rsync -av --delete /media/usb/backup/primary/ /media/usb/backup/secondary/
To sync files immediately, rsync can be run from the command line at any time with:
$ sudo rsync -av --delete /media/usb/backup/primary/ /media/usb/backup/secondary/
To make the primary SD card available as a Windows share, install and configure SAMBA:
$ sudo apt-get install samba samba-common-bin $ sudo vim /etc/samba/smb.conf [backup] comment = Pi backup share path = /media/usb/backup/primary public = yes browseable = yes writable = yes create mask = 0777 directory mask = 0777 $ sudo service smbd restart
Finally, install and configure UFW firewall, allowing incoming connections for SSH and SAMBA only:
$ sudo apt-get install ufw $ sudo ufw default deny incoming $ sudo ufw default allow outgoing $ sudo ufw allow ssh $ sudo ufw allow samba $ sudo ufw enable
