Robert Hulme wrote:
Hi,
I'm fairly new to NTP (although I have read a lot of the documentation
on the site and in the wiki) and I'm trying to get some expert advice to
help with an internal IT discussion occurring in the IT team at my
company.
We have about 20-30 linux servers collocated (on two sites - 95% of them
on one site) and about 30 windows desktops at a different site. The new
Linux sysadmin has noticed that the NTP client configuration on the
servers is fairly random (they seem to use various random UK ISP's NTP
servers (only one NTP server configured for each box)). Clearly that
needs sorting out - but in the course of the discussion there was a
debate about whether we ought to get a refclock.
Could you give some advice on how we should be thinking about this, what
we should consider, and what the pros and cons of using a refclock are.
For reference we basically do web hosting for our clients on these
servers - some run databases and so on but there is nothing particularly
unusual that the servers do.
If you think a refclock is a good idea or an important thing to have the
one that has been suggested is this one
http://www.atomic-clock.galleon.eu.com/Atomic-Clock-Time-Server/Atomic-C
lock-Time-Server.htm
If on the other hand there is a simple place I can RTFM then please
point me to it :-)
Robert Hulme
Technical Consultant
Anthony Hodges Consulting Limited
Direct line: (01924) 203904
Switchboard: (01924) 203900
Email: [EMAIL PROTECTED]
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You really need to define your requirements. When you have specified
the accuracy you need and the reliability you need, we can probably give
better advice. If traceability of your timestamps to a national
standards lab is a requirement be sure to mention that as well
A refclock, particularly a GPS timing receiver, provides an ultra stable
and ultra accurate reference. The stability means that clients can
synchronize with the server synchronized to that refclock and stay
within, say, 50 microseconds of it. A great deal depends on the
hardware and O/S being used. A refclock can, but need not, be
expensive; mine cost me $200 US. The cheapest I know of is about $85 US.
The fast, easy, and cheap solution, is to designate one of those Linux
boxes as your house timeserver and configure it to use four or five
internet servers. Then tell all the other boxes to synchronize with it.
You can expect everybody to stay within ten to twenty milliseconds of UTC.
If you need better reliability than a single in house server can
provide, you can use more. That is a good reason to define your
requirements up front.
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