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.
We hit another milestone in the last few days with 1000 active servers in Europe!
Now of course we need to get more servers added so we don't slump below that number again - right now the number is 999. Who will take us back over 1000? :-)
Growth in North America have practically stalled on the other hand; we could use more servers there too (and as always in Asia, South America and Africa, too).
Most people don't know, but the NTP Pool web site and monitoring software is actually licensed under the Apache Software License 2.0.
I did that to make it easier if at some point the community decides that my stewardship of the NTP Pool isn't good enough. Since installing the pool site doesn't make much sense other than for development I don't make ordinary releases, but all the code is available in my public subversion repository.
On a somewhat related note the project has an entry on ohloh. If you are an open source contributor and haven't seen that site before, you should give it a look.
I've been adding support to the NTP Pool site for translations again.
Before I took over the site it was translated in a bunch of languages, but as the site got dynamic features and more pages we lost that. Now it's back!
If you are interested in helping then send me a mail at ask@develooper.com. Experience with gettext (".po") files or Locale::Maketext lexicons and with version control (Subversion specifically) will be helpful, but if you are willing to learn then it isn't required.
Early this morning (PST) we had a few hours of "sub-optimal" performance on the monitoring server. A hundred servers or so were marked "bad" and got unnecessary warning mails because of it. users of the pool should not have been impacted. Work is in progress to permanently improve on this.
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