[time-nuts] Selecting server hardware (newbie question)
phk at phk.freebsd.dk
Sat Jan 28 04:54:52 EST 2006
In message <20060128092400.42708BDE0 at ip-64-139-1-69.sjc.megapath.net>, Hal Murr
>> I am trying to select a host machine for a dedicated NTP server. I
>> have several spare PCs to hand, with processor speeds around 500 MHz
>> - all my budget will allow for the moment.
>You will probably get more/better responses from comp.protocols.time.ntp on
>My 2 cents...
Another 2 cents:
>As a sanity check, several people use the Soekris Engineering net4501 as a
>It's got a 133 Mhz 486 class processor. (Runs cool.)
The 4501 is actually particularly good if you use the onboard
timers to timestamp your 1PPS signals:
I know of no other computer that can do this out of the box.
>The main source of instability is the temperature of the crystal.
Agreed. Replacing the 33 MHz xtal with something better is highly
>Most systems use the 32 KHz battery backed TOY (Time-of-Year) clock for
>timekeeping rather than the CPU crystal.
Wrong, few systems do. Most systems use the 32.768 kHz xtal to run
their battery-backed Real Time Clock, but this is only consulted on
boot to get an initial fix on time.
>This is good because it's generally
>farther from the heat generating CPU than the CPU crystal.
This has no hold in reality.
>For software, the PPS support needed by GPS clocks (and others)
>is part of the normal source code for some OSes. It's not on Linux
>but is available as an add-on. I suggest using whatever you are
>most comfortable/familiar with.
I'm obviously biased, but I think the FreeBSD code I wrote is an
order of magnitude ahead of anything else:
A Soekris NET4501, a bit of work with a soldering iron, an OCXO possibly
with a PLL to generate something roughly 33MHz and a GPS receiver
will get you about as good a NTP server as money can buy and at a
rock bottom price.
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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