KSplice is a paid service that applies important kernel security updates without the need to reboot the web server.
Generally, Linux servers rarely need to be rebooted due to updates. In contrast Windows servers need to be rebooted frequently after updates. When a server is rebooted, this means your website and email become available for a short period of time, generally minutes, while the server reboots.
Normally, if the Linux kernel requires an update, the server needs to be rebooted to apply that update. KSplice uses kernel modules to apply updates and patches against the kernel without the need to reboot. This means more uptime for your services.
Our servers have a minimum of 124 days of uptime at this point and time, partially due to ksplice.