[kwlug-disc] Server reboot time ...

[Khalid Baheyeldin]

On Mon, Oct 6, 2025 at 1:29 PM Khalid Baheyeldin <kb at 2bits.com> wrote:

> I am setting up a new Dell server for a client, so we can move the site to
> it.
>
> But I am bothered by the time it takes from shutdown to boot.
> It will not be a frequent event, but when it is happening, the site is
> down.
> So minimizing it is important ...
>
> Here is the logs from journalctl:
>
> Oct 06 16:27:48 foo systemd[1]: Reached target shutdown.target - System
> Shutdown.
> Oct 06 16:27:48 foo systemd[1]: Reached target final.target - Late
> Shutdown Services.
> Oct 06 16:27:48 foo systemd[1]: systemd-reboot.service: Deactivated
> successfully.
> Oct 06 16:27:48 foo systemd[1]: Finished systemd-reboot.service - System
> Reboot.
> Oct 06 16:27:48 foo systemd[1]: Reached target reboot.target - System
> Reboot.
> Oct 06 16:27:48 foo systemd[1]: Shutting down.
> Oct 06 16:27:48 foo systemd-shutdown[1]: Syncing filesystems and block
> devices.
> Oct 06 16:27:48 foo systemd-shutdown[1]: Sending SIGTERM to remaining
> processes...
> Oct 06 16:27:48 foo systemd-journald[1694]: Journal stopped
>
> -- Boot 67974696049a495c86f01b56d2a150dd --
>
> Oct 06 16:32:09 foo kernel: Linux version 6.8.0-85-generic (...)
> (x86_64-linux-gnu-gcc-13 ...
> Oct 06 16:32:09 foo kernel: Command line:
> BOOT_IMAGE=/vmlinuz-6.8.0-85-generic root=UUID=foo ro
> Oct 06 16:32:09 foo kernel: KERNEL supported cpus:
> Oct 06 16:32:09 foo kernel:   Intel GenuineIntel
> Oct 06 16:32:09 foo kernel:   AMD AuthenticAMD
> ...
> Oct 06 16:32:09 foo kernel: BIOS-provided physical RAM map:
>
> You can see it takes a full 4 minutes and 20 seconds to do ... nothing?
>
> Any ideas why it takes that long, or where to look?
>

I found out a significant contributor to the boot delay.

In the BIOS for the servers, PXE boot is enabled for all network
interfaces, and it is before other boot options (RAID controller, then
plain old disks).
Because it has to wait for each to time out, it adds up to several minutes
of delay.
Disabling PXE boot solves this issue.

-- 
Khalid M. Baheyeldin
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