ssh login - *** System restart required ***

While you can, you SHOULDN'T.

Issue reboot jobs from the Linode Manager. It makes everything happy.

It's totally fine to reboot via the shell. That said, the "System restart required" banner is likely telling you that you upgraded your kernel package, which has no effect on your Linode unless you're using pv-grub.

• Les

Issuing a reboot from the shell is actually identical to issuing a shutdown; Lassie (the Linode watchdog) will then detect the system has shut down and will start it up again.

I do find some timing differences though between the shell and Linode Manager, in terms of the downtime.

Doing it from the shell shuts down faster, but then you have to wait for Lassie to notice and execute the restart job. It doesn't take long, but there is some latency.

Doing it from the manager takes a little longer to get the shutdown job going (and have the guest actually shut down), but the restart job is queued up immediately so happens faster.

So while I've done it both ways, if I have access to the manager, I tend to take that approach as while it may not change the overall time for the restart, it helps minimize the actual down time.

– David

As akerl said, if it's a kernel update and you're not using pv grub you can ignore it, you should however reboot periodically to keep your linode kernel up to date (kernels are listed here https://www.linode.com/kernels/).

Other packages do sometimes create this flag, updates to openssl normally trigger it.

If you want to clear it without rebooting run rm /var/run/reboot-required

Many thanks everyone. :)