If you are IPv6 connected, the www.pool.ntp.org site will now be delivered to you via IPv6.
I did tests on a hundred thousand visitors to the site and nobody who could connect with IPv4 had trouble talking to a site with both "AAAA" and "A" records. The test only included users with javascript however, so it could still miss appliances, older boxes etc. More tests are needed to make the pool.ntp.org service "ipv6 enabled".
In our ongoing process of getting the NTP Pool IPv6 compatible we took a first (small!) step getting the website partially available via IPv6. For now it's via an IPv6-only hostname: www6.ntppool.org.
So far the anecdotal reports are that it's working fine for people with IPv6. The next tests will be to see how connectivity is affected for everyone else if a host has both AAAA (IPv6) and A (IPv4) records in DNS.
As part of the same change, the website is now served through Varnish which makes it a bit faster and more importantly makes it inconsequential when people rudely try to "sync time" via HTTP to the server.
The pool keeps growing (although we still need more servers).
Recently we've added zones and servers in Costa Rica, Venezuela, Serbia, Croatia, El Salvador and New Caledonia.
But we need more servers all over the world. In smaller developing countries internet use is picking up and local servers will help. In bigger countries usage is also growing faster than the number of servers; so extra help is needed. We're getting close to 2000 [active servers] - but for millions and millions of users we need more.
Sometimes I’m asked if the NTP Pool really needs more servers. The answer is yes, always!
While the number of servers has grown nicely over the years, so has the number of users so we need
The only (tricky) requirement is that you have a static IP address and expect the server (and IP) to be around for a long time. ntpd doesn’t deal well with changing IP addresses (yet), so this is important.
It really depends on which country you are in; but you can heavily regulate it with the “netspeed” setting in the server settings on the manage page. As a rule of thumb you’ll get 1/3 query a second “per megabit”; with peaks of about 1 to 1.5 queries per second per megabit at the top of each hour (yeah, lots of people are unhelpfully synchronizing their time at the hour each hour). Each packet is only about 50 bytes, so this is very little traffic. If you set the netspeed to for example 1 mbit (the default) you’ll get very little traffic but still help tens of thousands of users a day set their time.
In some countries you might get more queries; but that just means that the need for your server is greater in that country!
As mentioned a few months ago, NTP operates exclusively with UTC time. If your system is (typically) one hour off after syncing with the NTP Pool then it's because your operating system needs to be configured with the correct timezone and daylight saving time setting. If you live in a place that recently changed rules for daylight saving time you need to make sure you have the latest system updates installed.
The goal of the NTP Pool is to provide accurate time to everybody. Though internally it's really about serving DNS requests. Quite a lot of them, and ideally fast.
Through history we've ended up with using the 'pool.ntp.org' domain for client access which for performance isn't really optimal, but it's what we have. Through a bit of administrative division it ends up that just to find out who to ask for the IP of '1.fedora.pool.ntp.org' you have to send a whole lot of DNS requests out.
While the DNS system is resilient in handling failures, to get decent performance it's important that each "layer" has fast and highly available servers. To that end we're fortunate that Dynect are providing Anycast DNS services for the NTP Pool (about 300 million requests a month right now, and we're just getting started).
For now we're just using Dynect for the ntpns.org zone, but in the future we're looking forward to also using their failover system to help make sure the pool website is always available.
Due to the distributed nature of the pool system we don’t know exactly; but based on some sample measurements we estimate that the overall pool system on average handles somewhere between 40 and 120 thousand NTP requests per second.
If we assume it’s 50,000 a second, that makes a bit over 4300 million requests a day!
In a year that’s about 1500 trillion (american) / billion (other countries) requests a day. (1576800000000, if I’m counting the zeroes right).
That’s a lot of accurate time distributed; and yet triains, planes and meetings run late. :-)
In many places around the world March is the month of changing clocks as daylight saving time comes and goes.
Usually a number of users write to tell me that the NTP Pool is an hour off during this time and in the fall when clocks change the other way. Happily it isn’t so; because NTP is based on the almost stable Coordinated Universal Time (aka UTC).
If you use NTP and your clock is an hour off, you either need to update your operating system with the latest patches for the time zone information or you need to check that your time zone is configured correctly and “adjust automatically for daylight saving time” is enabled if that option is provided.
For people in the Northern Hemisphere: Enjoy spring and the increasing daylight!
For those of you on the other side: Sorry, but it’s our turn to have longer days now. :-)
Happy New Year everyone! Please take a moment to remind your fellow sysadmins about registering their servers in the pool if they have servers meeting the requirements (~100% uptime and a static and stable IP address).
As mentioned earlier the pool system now has partial support for IPv6 servers.
It's currently limited to just getting the servers registered though! They are not monitored and the pool DNS system does not give out AAAA records.
The plan is to start testing various approaches to IPv6 support during 2009. Stay tuned.
This morning I pushed the latest version of the NTP Pool Server code to www.pool.ntp.org. The news are:
Runs on the code from the git repository
Translations are back! The end-user portions of the site is now available in English, Dutch and French.
Partial IPv6 support (thanks to Martin von Löwis). More about this in the next post.
Apache 2 / mod_perl 2 support - this makes it much quicker to setup a development sandbox.
Various bugfixes.
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