In message <[EMAIL PROTECTED]>, Hal Murr ay writes: > >> 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 >usenet. > >My 2 cents...
Another 2 cents: >As a sanity check, several people use the Soekris Engineering net4501 as a >NTP server. > http://www.soekris.com/net4501.htm >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: http://phk.freebsd.dk/soekris/pps/ 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 advised. >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: http://phk.freebsd.dk/pubs/timecounter.pdf Summary: 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 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
