I get this question a lot, and figured it’s about time to address it. Once you’ve finished a Raspberry Pi Home Server, and have it booting from the hard drive, how are you supposed to take backups? After all, you can’t just pop out the SD card and just run it through Win32DiskImager anymore.
If your main computer is a Mac or Linux machine, then you can simply shut down the Pi, hook it up to your main computer, and use the “dd” command to make a copy of the OS partition in the same way you wrote the SD card in the first place, but with the “if” and “of” parameters reversed.
If your main computer is a Windows machine, then one answer is to create a secondary, minimal SD card or the Pi. You can use Raspbian Lite for this, since you won’t need anything but the command line. Then, you just shut down the Pi, drag it back over to your desk and hook it back up to the monitor and keyboard, swap the SD cards, boot up using the new SD card, and use the “dd” command to write a backup of the OS partition to the Data partition on the same drive, or mount a flash drive, and back up to there.
But wait… there’s a much simpler option. You can just attach the hard drive to your Windows computer, and use Win32DiskImager to take a backup of the whole hard drive. You’ll get a snapshot of the complete working state of the system this way. If the drive attached to the Pi is very large, then I realize this may not be an option, but let me tell you about my current setup.
My Raspberry Pi Home Server has two drives these days. The first is a smallish SSD (like 60GB small) that I have long since “traded up” from. It still has two partitions on it, a 16GB OS partition, and a Data partition, but that’s not where most of my actual stuff goes. I use the Data partition on this first drive for things like the swap file, MiniDLNA’s database, and CrashPlan’s metadata, but my actual music, movies, pictures, and CrashPlan backup files are all on a second hard drive, which is the 2TB RAID. In this way, I’ve completely separated my “stuff” from the system. The storage drive is blissfully unaware of the Pi’s existence. I still format this drive using NTFS, so I can just plug it into my regular computer and get to my stuff.
By the way, I don’t really use Win32DiskImager anymore, either. These days I use HDDRawCopy, which has the added benefit of writing out compressed image files, so instead of creating a 60GB file and then Zipping it up to get my hard drive space back, I end up with a file that’s already compressed in the first place.
Every now and then, after doing system upgrades, I’ll shut the whole thing down, hook the primary drive up to my regular computer, and create a new image. This image contains not only the OS, but the current state of the Data partition as well. If I’ve added music or movies since the last back up, then MiniDLNA will have to play catch-up when the system starts up, but eventually, it all sorts itself out.
But what if you only have a single, very large drive hooked up to the Pi? There are many programs available that will let you back up individual partitions. I don’t have a personal favorite here, but I would welcome recommendations in the comments.
I’ve heard good things about Paragon Backup & Recovery, and Macrium Reflect Free, but I don’t know if backing up and restoring individual partitions is included in their free versions or not. Also, I think the free version of Paragon is limited to backing up and restoring drives that are 2TB or less. I’m not sure about Macrium. Perhaps I’ll find the time to do some testing on these free solutions and update this post a bit later on.