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Fast Boot & Reboot

"Fast" is a relative term when it comes to server hardware. The BIOS tends to do a lot more checks, which makes the process inherently slow. But the OS itself has a lot to do when shutting down everything and bringing it back. I prefer this to be as fast as possible.

Setup

Unlike the installation times in a VM, these times are on actual server hardware. As such, it's important to describe the servers a bit and what they're doing.

  • Process load
    • FreeBSD: 8 jails (considerably more)
    • Debian: 1 LXC/LXD container
  • Disk Encryption
    • FreeBSD: 6 geli-encrypted HDDs, 5400 RPM
    • Debian: 4 luks-encrypted HDDs, 7200 RPM
  • CPU

Spec-for-spec, Debian has an unfair advantage. Less load, less drives, newer drives, faster drives, and a faster CPU.

Results

FreeBSD reboots in two-thirds of the time of Debian, despite the hardware disadvantages and despite having more things to get started at boot.

OS Reboot
to
BIOS		 BIOS to
Loader
(BTL)		 Loader
to
Kernel		 Kernel
to
Login		 Total Total
Minus
BTL
FreeBSD 13.2 20s 39s 5s 58s 122s 83s
Debian 12.1 25s 42s 10s 91s 168s 126s

These results are far from scientific, but FreeBSD consistently boots faster for me. On the same hardware, Linux systems like Void would take incredibly long to shutdown virtualization tasks. I found Arch Linux configured with systemd boot would perform the best of the Linux options, but still slower than FreeBSD. I suspect the main bottleneck is the LUKS decryption step. FreeBSD seems to zip right through this with geli(8).

In short, FreeBSD wins the race. It's probably not the most important criteria, but less downtime is better. If I must reboot, I want it to be snappy.