Hi Paul, This is probably going further up the track for you, however, with the HP "c class" blades you can use a PCI expansion blade with a serial IO card in it. The downside is that the expansion blade takes up one bay (to the left of a half-height blade, or bottom left slot next to a full height blade) If your enclosures are already quite full this maybe a problem for you? Another thought is the SUV Dongle that goes on the front, breaks out com1 to the DB9 on the Cable. However, loss of PPS due someone hijacking the cable for service reasons is probably quite high... I wouldn't recommend epoxying the cable in unless you are going to use the cheapest available blade and intend to chuck it if it fails.
Another thought is to use the HP SL type blades, some of which have expansion slots natively. These are not so well known, however video rendering farms seem to love them.. I wish you luck on your exciting project, feel free to drop me a line if you have any HP blade or ISS technical related questions? Mark -----Original Message----- From: Paul Sobey [mailto:bud...@the-annexe.net] Sent: Saturday, 24 December 2011 1:47 AM To: questions@lists.ntp.org Subject: Re: [ntp:questions] Accuracy of NTP - Advice Needed Our problem will be that running coax around many sites to lots of machines, many of which don't have serial ports (think blades), is both highly time consuming and maintenance intensive. If we have to do it then we will but I'd like a clear idea as to the whys before I start down that particular path. In particular at this stage I'm trying to understand more about the theoretical accuracies obtainable under ideal conditions, and most important, how to independently verify the results of any tweaks we might apply. Say I have coalesence turned on a nic and I disable it - I'd like to be able to determine the effect, if any of that change. Is it possible for ntpd (or ptpd) to accurately determine its own accuracy, if that makes sense? If not what techniques might I use to independently measure? On a related note, I'm aware that there are various methods for querying the system time, some of which involve a context switch, and some of which can be done cheaply in userspace. I'm not sure whether the same is true for setting the time. Is anyone aware of how much ntpd operation involves context switches, which obviously would place quite a high ceiling on accuracy since we're at the mercy of the OS scheduler? Cheers, Paul _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
