A few months ago, I switched my backup server to an ODROID-M1 SBC. It uses a RK3568 SoC with a quad-core Cortex-A55 and AES extensions (useful for disk encryption), and I added a 2 TB NVME SSD to the M2 slot. It also has a SATA connector, but the default enclosure does not have space for 2.5" drives. It's not the fastest SBC, but it runs stable and quite well as a backup server, and it's fanless, and low-power (less than 2 W idle). The support for the SoC has been added recently to the Linux kernel (it's used by various SBC), however the device tree for the ODROID-M1 was missing, so I contributed it based on the vendor one, and also submitted a few small fixes.

All the changes ended in the Bookworm kernel, and with the Bookworm release approaching, I decided it was the good moment to upgrade it. It went quite well, and now I can enjoy running dist-upgrade like on other stable servers without having to care about the kernel. I am currently using Borg as a backup software, but the upgrade also gave access to a newer Restic version supporting compression (a must have for me), so I may give it a try.