Questions tagged [time-synchronization]
249 questions
110
votes
10 answers
How do I update a CentOS server's time from an authoritative time server?
I have CentOS machine and each time I've noticed that the server loses correct time after a while. It is usually behind by several minutes after time passes from having manually set the correct time. Is there a mechanism whereby I can update the…
user111196
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41
votes
4 answers
Windows Server unable to synchronize NTP time reliably
Why does Windows Server (2008, in this case, but I've seen the same problem in 2003) seem to have problem synchronizing time? I've seen this error in my System log across a variety of servers:
The time service has not synchronized the system time…
Jeff Atwood
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37
votes
12 answers
Is anyone using GPS for time sync?
I've come across a handful of GPS NTP servers, as well as some inexpensive solutions using off-the-shelf receivers and software. Right now I'm just using NTP with a list of servers over the Internet. What is the advantage to using GPS instead…
user640
35
votes
6 answers
Why is it important that servers have the exact same time?
I have read multiple times (although I can't find it right now) that data centers take great effort to make sure that all server have the exact same time. Including, but not limited to worrying about leap seconds.
Why is it so important that servers…
Jens Schauder
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27
votes
3 answers
NTP is running, system clock still not in time - what gives?
A Debian Stable (5.0.3) server is running ntpd, and connected to the internet. Still, the system clock is about 5 minutes wrong.
$ /etc/init.d/ntp status
NTP server is running..
Relevant parts (I think) of /etc/ntp.conf:
driftfile…
Jonik
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20
votes
6 answers
How to keep time on resumed KVM guest with libvirt?
On my host I am using libvirt and a KVM guest. When the host is shutting down, libvirt suspends the guest. When the host is starting up, libvirt resumes the guest. The problem is, if the guest is suspended and resumed after 24 hours for example,…
Hristo Hristov
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14
votes
2 answers
What can be done to improve time synchronization on networks with sporadic internet access?
I'm looking for advice setting up time servers for a very non-typical network. I support many closed networks that have occasional access to the internet. A network would get access most days for a few hours, but would frequently go 1-3 weeks…
anregen
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14
votes
4 answers
How to set a frequent period for NTP client to sync with the NTP server
I've setup an NTP client for my DC to sync time with time.windows.com but I want it to query the NTP server at least twice a day. I made all the changes via the registry, is there a period registry I can amend and how?
stead1984
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12
votes
3 answers
How to synchronize time on ESXi Windows virtual machines within one second?
I'm a developer and we are using Quartz.Net, widely used scheduling library with SQL backing store to run cluster of jobs servers (VMs on ESXI cluster).
Quartz.Net requires that time will be synchronized between job server instances and recommends…
Leotsarev
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12
votes
9 answers
12
votes
2 answers
How to change time source from "Local CMOS Clock" to "DC"
In a domain, I want to set DC as time server.
To do that I use this command:
w32tm /config /manualpeerlist:europe.pool.ntp.org /syncfromflags:manual /reliable:yes /update
and
w32tm /resync /rediscover
In the client servers I use
net time…
Barny
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11
votes
3 answers
How come one of my switches is off by two minutes in spite of ntp?
I just noticed by pure chance that one of my Cisco 4500 switches has its clock going wrong: it is more than 2 minutes behind in spite of seemingly functional ntp. In my opinion, even a single second should not be considered acceptable for the…
Hagen von Eitzen
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11
votes
3 answers
Timesync on HyperV with CentOS 6.2
I've got a CentOS VM (release 6.2) running under HyperV. I have integration services installed (part of base now), and CentOS shows the current clocksource is hyperv_clocksource, however my time in the VM is about 10 minutes fast after a week of…
WaldenL
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10
votes
7 answers
Hyper-V Machine drifts time all over, even with NTP
Resolved
The problem was Hyper-V on that machine. I removed Hyper-V, installed VMware Server, ran the same VM. Time sync issues went away (< 100ms difference after a day).
My setup is like this:
HYV1 - HyperV machine (non domain) - sync…
MichaelGG
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8
votes
3 answers
Ntpd on local network - Preventing clock drift causing high offsets
I have a local network with a microcontroller ARM as the NTP server and I have a desktop computer running with ubuntu 16.04 LTS as a NTP client.
Once I start ntpd -g -c /etc/ntp.conf with the following ntp config file
server 192.168.0.11 minpoll 4…
Daniel R.
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