More virtual servers and a competition

September 24th, 2013 by

We’ve just extended our range of Virtual Servers to include a 512MB “VS Lite” option for just £7 + VAT per month – or the equivalent of £5.83/month if you pay annually.

We’ve been doing Virtual Servers for 10 years now, and we’ve always hosted them on machines with hot-swappable hardware RAID, meaning that we can replace failed disks without customers even being aware that there was a problem. One of the great things about virtualisation is that reliability shares really well – but it still adds a bit to the cost

A large proporption of our Dedicated Server customers use machines without hot-swappable drives, and we thought we’d extend the option of using cheaper hardware to our Virtual Server range in the form of the VS Lite, our most affordable Virtual Server yet.

The VS Lite host hardware still has monitored RAID, so we can cope with disk failures without data loss*, but it requires downtime in order to replace the drive.

Our standard Virtual Servers start at £12.50 + VAT per month for a 1GB server, and all run RAID-10 on hot-swappable drives, and offer a choice of data centres, allowing you to spread multiple servers across geographically diverse sites.

In the unlikely event that even £7/month sounds expensive, then we’ve got an even more affordable alternative with a bit of a twist up our sleeves which we’ll be unveiling shortly. The first person to guess what we’re planning can have one free for a year, and don’t worry, as with all our Virtual Servers you can upgrade and downgrade easily, so don’t be put off by the prospect of an even better offer in the pipeline!

On the other hand, there are no prizes for guessing what hardware we’re using for the VS Lite host servers…

* RAID is not backup.

DNS API – Implementing Dynamic DNS

September 21st, 2013 by

Last year we announced some improvements to the Mythic Beasts DNS API, and I asserted that this made it good for implementing a Dynamic DNS service. Dynamic DNS is simply a mechanism for programmatically updating a DNS record, typically used to provide a consistent name for a computer that is at the end of an internet connection with a dynamically assigned IP address.

Well, last weekend I had the opportunity to try implementing a Dynamic DNS service with our API, and realised that it actually makes the task unduly difficult. It can be done, but in order to change a record, you need to remove the old record, and to remove the old record you need to know what it is currently. This meant that you had to use the LIST command, grep out the old record, and then issue the necessary DELETE and ADD commands. Aside from being hassle, it introduces an unavoidable race condiition between the LIST and DELETE commands.

We’ve now implemented the obvious fix: a REPLACE command, which replaces all existing records for the specified host and type, and replaces them with the one provided. Obviously this doesn’t work if for some reason you want multiple records for a single host, but for the obvious use case it means that Dynamic DNS can be handled in a single command:

curl --data "domain=MY_DOMAIN&password=MY_PASSWORD&command=REPLACE \
myhost 300 A"

The DNS API is a standard feature included with all Mythic Beasts domain registrations. Full documentation can be be found here.

IPv6, End users starting to care

September 17th, 2013 by

We’ve had an IPv6 aware network for quite some time, and we’ve been gradually rolling it out to our services with the aim of eventually having every service we offer fully available over IPv6 and IPv4. We host the Raspberry Pi website which has an IPv6 only internal network, IPv6 only virtual machines and IPv4 on the front end to help out those of you with the ‘legacy’ internet.

A quick skim over the logfiles suggests that about 96% of you still access the site through the legacy IPv4 network – about 4% of hosts are now connecting over IPv6 which is starting to become a non trivial fraction of the traffic. Of course this is much higher than typical sites, Raspberry Pi users are much more technically aware than the general population.

Yesterday we had our first real connectivity problem to investigate – an end user within (the UK academic network) was unable to access files from the Raspberry Pi download server on about half of the occasions. Further investigation showed that they could access the load balancers in our Sovereign House site with connectivity via the London Internet Exchange Juniper LAN, but not the load balancers in our Harbour Exchange site with connectivity over the London Internet Exchange Extreme LAN.

When we started investigating we confirmed that it seemed to be a problem with the Extreme LAN, if we forced the connectivity via the Juniper LAN it worked from both sites, if we forced it via the Extreme LAN it failed from both sites. Odder and odder though, a packet dump on our LINX interface didn’t show us passing the packets on.

Our IPv4 peering worked fine, this was IPv6 specific.

We then started looking at the routing table on the router. Over IPv4 it looks like via dev eth0

and over IPv6 it looks like

2001:630::/32 via fe80::5e5e:abff:fe23:2fc2 dev eth0

That gives us the netblock, and the next hop to send the packet to.

So the next step is to check you can reach the gateway happily enough.

# ping
PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=64 time=0.220 ms


# ping6 fe80::5e5e:abff:fe23:2fc2
connect: Invalid argument

Odd. Then I realised that fe80:: in IPv6 means a link local address – the address is specific to the network card so to ping it you have to specify the destination address and the network interface.

# ping6 fe80::5e5e:abff:fe23:2fc2 -I eth9
PING fe80::5e5e:abff:fe23:2fc2(fe80::5e5e:abff:fe23:2fc2) from fe80::21b:21ff:fe65:a4c5 eth9: 56 data bytes
64 bytes from fe80::5e5e:abff:fe23:2fc2: icmp_seq=1 ttl=64 time=0.451 ms

Then the penny dropped. The routing table has eth0 in it but we’re actually connected to eth9. Under IPv4 this is fine because the next-hop address is globally unique and only accessible over eth9 so we send the packets out of eth9 and they go to the correct destination. Under IPv6 it’s a link local address and therefore valid over any interface, so we obey the routing table and throw the packets out of eth0 whereupon they fall onto the floor because there’s no fibre connected.

Fixing the config to put the right interface description in made it all work, and our end user is happily able to access all the load balancers on all the v6 addresses in all of the buildings.

Obviously if you’re a Mythic Beasts customer and you don’t already have an IPv6 allocation for your real or virtual server, drop us an email and we’ll hand you your own address space to play with.

I do not accept your silly software license

September 9th, 2013 by

So our newest Mythic Beast started working for us today. The first task is to start installing your new laptop and reading and signing employment contracts. Today we had our newest employee fail at the first hurdle.

The laptop in question is a shiny Toshiba z930. This one came with Windows 8 and a fully charged battery. On first powering it on it comes up with the Windows 8 licence. This has a tickbox option for ‘I accept the license’ and a big button labelled ‘Accept’ to click on.

If you don’t tick the box, it tells you you have to. There’s no option to reject the license.

If you press the power button the laptop suspends itself. If you press and hold the power button the laptop still suspends itself. Ctrl-Alt-Delete doesn’t work. You can’t remove the battery as it’s built in. In frustration our newest employee suggested pouring his coffee over the damn thing to make it power cycle. This was a really stupid idea, not only does the laptop have a spill proof keyboard he’d also then have no coffee.

The best plan we could come up with was to wait for the batteries to run out which requires pressing a key about every five minutes to stop the thing suspending itself.