Reboot scheduled for host "bellini", 2012-02-20 2200Z; host "president", 2012-02-21 2200Z

Hi folks, Short version: Two of our servers appear to be subject to a now fixed kernel bug affecting IPv6, and require a reboot for kernel upgrade. Host bellini.bitfolk.com will be rebooted on Monday 20th February at 2200Z. Provided that does fix the problem, host president.bitfolk.com will be similarly rebooted the following day, Tuesday 21st February also at 2200Z. Longer version: While investigating some recent reports of poor IPv6 performance, it seems that both bellini.bitfolk.com and president.bitfolk.com are affected by a bug in the igb Intel gigabit Ethernet driver as described here: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=630730 The symptoms are very poor IPv6 performance in the region of a maximum of 100kilobit/sec. On doing a tcpdump you will see packets of length greater than 1500 bytes, followed by an ICMP6 "packet too big" message coming from our server, and then a retransmit. These hosts have been up for 138 days (bellini) and 223 days (president), and unfortunately neither we nor any customers noticed any problems until recently. On casual inspection IPv6 works. It's only noticeable when trying to do a larger data transfer. Since the current impact is so low, I am not going to rush to reboot these hosts. I would rather give plenty of notice to those who need it. When it's time for the reboot we will shut down all VPSes on these servers cleanly, reboot the machine and then begin booting them up again. Downtime is expected to be in the region of 15 minutes. If you are in any doubt as to whether your VPS starts cleanly with all required services running, you should test this ahead of time. I am fairly confident that the problems observed are caused by that bug and therefore that a kernel upgrade will fix it, but unfortunately we do not have any other hardware that uses the igb driver. If doing the upgrade on bellini does not resolve the issue then we will have to consider our options. In the mean time, if your VPS is hosted on bellini or president then you may wish to set your VPS to prefer IPv4 DNS results ahead of IPv6 results: https://tools.bitfolk.com/wiki/IPv6#Preferring_IPv4_over_IPv6 Cheers, Andy -- http://bitfolk.com/ -- No-nonsense VPS hosting