Are faster reboots possible?
I found this old topic on this specific issue. Though Linode's are KVM based now, a reboot from the Linode itself will still shut down the system, rather than reboot it without placing a job in the queue. There are less things that actually require a reboot now than before, such as network configurations, etc. If not the default, I wonder if something like this could be an option.
In experimenting with an alternate VPS hosting company, I am able to get reboots in perhaps five seconds using syslinux as the bootloader, and no prompt, no menu displayed, simply booting immediately to a specified entry configured in the boot loader configuration file. I really like this for kernel upgrades and anything else requiring a reboot, but unfortunately, I can't get such speeds on Linode, even when rebooting via lish.
There would be a couple disadvantages to this that I can see.
- Any kernel panic or system crash that initiates a reboot would not send you a job notification of a Lassie reboot.
- Anything that would require a complete reboot of the system, a shut down of the virtual machine Hypervisor and reloading, would not work while rebooting from the Linode itself if it instantly restarted without reloading the Hypervisor.
If this was an available option, to reboot without actually shutting everything down and placing a boot job in the queue, I could personally deal with the disadvantage, as a full reboot should still be available from Lish or the Linode cloud manager.
I am aware of Kexec, but in experimenting with this, I noticed that sometimes, network connections over UDP traffic, and perhaps in general, are slower and not as stable.
How many might be interested in this, would it be something Linode might be willing to offer?
Hey Blake - since Linode offers GRUB2 and the Linode kernels, you may be able to add syslinux as the bootloader to a custom compiled kernel on a custom Image for additional testing on our platform. I've never done it though so I can't speak from experience.
I have gone ahead and submitted your feedback regarding faster reboots to our internal tracking for improvements. We'll be sure to reach out regarding this if/when it gets implemented.
I've done this on some custom images, building a raw image from one Linode and booting from it in the configuration you've described, using syslinux as the boot loader, and disk image for the Kernel in the profile. In this configuration, as you probably know, it boots via a bios configuration and searches for the MBR. Unfortunately, if you reboot such an image from the Linode, it will still be shut down as I described in my post, and thus, the reboot will still occur as I've stated, unless there's been a recent change that I don't know about.