Re: [ntp:questions] VM host not snyching time
David Woolley da...@ex.djwhome.demon.invalid wrote in message news:hobhio$u1...@news.eternal-september.org... Ramesh wrote: I am trying to synchronize the time of my VM server with ntpd. I have the following configuration. Not a good idea. VMs play tricks with time. They shouldn't be used for applications that require high precision time and any time synchronisation should be done on the host. He _is_ synchronising the host. Or trying to. Do VMs still have problems responding to timer ticks when there are enough cores to go around? Groetjes, Maarten Wiltink ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VM host not snyching time
Maarten Wiltink maar...@kittensandcats.net wrote: Do VMs still have problems responding to timer ticks when there are enough cores to go around? If anything, the problems tend to get worse when you have many cores. I am trying to get everything working in a VM environment right now, and I have many different versions of Windows and Linux running on a set of VMware ESX 4 servers. Every version of Linux needs different tweaking to get it working reasonably. I am not asking very high accuracy, I just want the time to be within a few hundred milliseconds and not jumping around or getting completely unsynced. This requires a lot of attention, much more than in the usual NTP environment (which merely requires patience). ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VM host not snyching time
On 2010-03-24, Maarten Wiltink maar...@kittensandcats.net wrote: David Woolley da...@ex.djwhome.demon.invalid wrote in message news:hobhio$u1...@news.eternal-september.org... Ramesh wrote: I am trying to synchronize the time of my VM server with ntpd. I have the following configuration. Not a good idea. VMs play tricks with time. They shouldn't be used for applications that require high precision time and any time synchronisation should be done on the host. He _is_ synchronising the host. Or trying to. That is not clear. If he is trying to sync it from a VM OS, it will not work. If he is syncing the base OS, then it should work. It is unclear what he is trying to do. It would help if he told us what he has done to reach his goals. Do VMs still have problems responding to timer ticks when there are enough cores to go around? Groetjes, Maarten Wiltink ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VM host not snyching time
Maarten Wiltink wrote: David Woolley da...@ex.djwhome.demon.invalid wrote in message news:hobhio$u1...@news.eternal-september.org... Do VMs still have problems responding to timer ticks when there are enough cores to go around? Were I work, the number of cores are seriously over-committed, as is memory. Many modern server applications are designed to use all the cores that they can get. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VM host not snyching time
David Woolley da...@ex.djwhome.demon.invalid wrote: Were I work, the number of cores are seriously over-committed, as is memory. Many modern server applications are designed to use all the cores that they can get. The Law of Unintended Consequences strikes following the Demise of Timesharing :) rick jones -- Wisdom Teeth are impacted, people are affected by the effects of events. these opinions are mine, all mine; HP might not want them anyway... :) feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VM host not snyching time
On Wed, Mar 24, 2010 at 7:49 AM, Rob nom...@example.com wrote: Maarten Wiltink maar...@kittensandcats.net wrote: Do VMs still have problems responding to timer ticks when there are enough cores to go around? If anything, the problems tend to get worse when you have many cores. Multi-core VMs present a significant challenge in a virtualized environment, as the cores themselves can actually run at slightly different times rates, and may be de-scheduled by the hypervisor at different times. And this disparity between cores has actually become even greater in the most recent VMware 4: http://www.vmware.com/files/pdf/perf-vsphere-cpu_scheduler.pdf Great for aggregate application throughput, but not so good for NTP. I wonder if setting affinity for NTP to a single virtual core would help. -- RPM ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] VM host not snyching time
Hi, I am trying to synchronize the time of my VM server with ntpd. I have the following configuration. And in the /etc/ntp.conf, I have the following line: restrict default ignore restrict 127.0.0.1. server time1.server server time2.server Whenever I have this line, the erver is not able to synchronize its time... So far as I understood, this line prevents other servers using this machine as a time server. And the second line says to allow localhost to use as time server. But why do I need to use its own time server when I have specified to use time1.server and time2.server ? ( firewall for tcp and udp ports 123 is open) However, when I replace the first line of the configuration with the following line, it works.. restrict default kod nomodify notrap noquery But with this, i am allowing other servers to use this server a ntp (which I wouldn't like to). Why this machine tries to use ntp server of its own (to snyc time) and why it is not working though i have the entry restrict 127.0.0.1 ?? Your comments will be highly appreciated. Thanks. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VM host not snyching time
Hi-- On Mar 19, 2010, at 12:39 PM, Ramesh wrote: I am trying to synchronize the time of my VM server with ntpd. You didn't mention which time of VM you are using, but normally it is better to run ntpd only in the host ESX for VMware, Dom0 for Xen, etc. See: http://xen.epiuse.com/xen-faq.txt http://www.nabble.com/Unable-to-set-system-clock-on-domU-td22042252.html I have the following configuration. And in the /etc/ntp.conf, I have the following line: restrict default ignore restrict 127.0.0.1. server time1.server server time2.server Whenever I have this line, the server is not able to synchronize its time... So far as I understood, this line prevents other servers using this machine as a time server. And the second line says to allow localhost to use as time server. But why do I need to use its own time server when I have specified to use time1.server and time2.server ? ( firewall for tcp and udp ports 123 is open) You need to add restrict lines for each host that you don't want the default restrict line permissions to apply, such as: restrict time1.server restrict time2.server Regards, -- -Chuck ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VM host not snyching time
Ramesh wrote: I am trying to synchronize the time of my VM server with ntpd. 13.6. VMware and NTP http://psp2.ntp.org/bin/view/Support/VMWareNTP 9.2.2.1. VMware http://psp2.ntp.org/bin/view/Support/KnownOsIssues#Section_9.2.2.1. -- E-Mail Sent to this address blackl...@anitech-systems.com will be added to the BlackLists. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VM host not snyching time
Ramesh wrote: I am trying to synchronize the time of my VM server with ntpd. I have the following configuration. Not a good idea. VMs play tricks with time. They shouldn't be used for applications that require high precision time and any time synchronisation should be done on the host. However And in the /etc/ntp.conf, I have the following line: restrict default ignore restrict 127.0.0.1. You are missing restrict lines to open up access to the servers. There is no implicit permission to receive from your servers. server time1.server server time2.server ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] VM host not snyching time
On 2010-03-19, Ramesh cfm...@yahoo.com wrote: I am trying to synchronize the time of my VM server with ntpd. I have the following configuration. And in the /etc/ntp.conf, I have the following line: restrict default ignore restrict 127.0.0.1. server time1.server server time2.server Whenever I have this line, the erver is not able to synchronize its time... So far as I understood, this line prevents other servers using this machine as a time server. restrict default ignore tells ntpd to ignore all NTP packets. This blocks all access to and from your ntpd. When you use restrict default ignore you must explicitly relax the restrictions for your remote time servers and your authorized clients. http://support.ntp.org/Support/AccessRestrictions http://www.eecis.udel.edu/~mills/ntp/html/accopt.html (ntp-dev documentation) http://doc.ntp.org/4.2.6/accopt.html (stable release documentation) And the second line says to allow localhost to use as time server. No, that line does not enable time service. restrict 127.0.0.1 relaxes the restrictions for connections from the localhost (e.g. for status queries). -- Steve Kostecke koste...@ntp.org NTP Public Services Project - http://support.ntp.org/ ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
