Questions tagged [clock-synchronization]
58 questions
27
votes
3 answers
How far is "too far off" for ntpd? Can it get there by a sudden jump to heavy load? Can this be overridden?
In many primers on ntpd, like this one, there's always a warning that ntpd will stop resetting the clock "[if] your clock is too far off."
How far off is "too far off"?
Also, if a server takes a sudden jump to heavy load, for example from total…
user144330
14
votes
3 answers
Synchronize clock with NTP while online, and with RTC while offline?
Is there a existing mechanism that synchronizes a linux system with NTP while online, and with a predictably drifting RTC while offline?
We operate remote "collectors": embedded Linux systems that collect and timestamp sensor data. We need their…
![](../../users/profiles/165450.webp)
Nils Toedtmann
- 3,202
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9
votes
1 answer
Force chrony time check
Context:
Centos 7.0
chronyc (chrony) version 3.1 (+READLINE +IPV6 +DEBUG)
Issue
I want to find a way to force chronyd to change the hardware clock
instantly without waiting.
The program chronyd is currently running on my machine :
[root@localhost…
![](../../users/profiles/436156.webp)
Orelsanpls
- 193
- 1
- 1
- 6
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…
![](../../users/profiles/492785.webp)
Daniel R.
- 211
- 2
- 7
8
votes
2 answers
Red hat Linux + TIME ZONE CONFIGURATION + details from clock file
In order to configure the Time Zone on red hat Linux machine ( version 5 and 6 )
need to configure
the file:
/etc/sysconfig/clock
And create a symbolic link between
/etc/localtime to /usr/share/zoneinfo/America/New_York
but /etc/sysconfig/clock…
![](../../users/profiles/346089.webp)
dandan
- 1,021
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8
votes
6 answers
What consequences / implications can arise from a wrong system clock?
What issues can you think of that may arise from a wrong system clock setting ?
Primarily interested in potential problems affecting servers and Linux or UNIX-like systems in particular.
And how severe are these consequences, depending on how much…
![](../../users/profiles/55347.webp)
Arc
- 343
- 4
- 9
7
votes
3 answers
hwclock: Cannot access the Hardware Clock via any known method
On a Debian server, I'm having problem with hwclock:
$ hwclock --show
hwclock: Cannot access the Hardware Clock via any known method.
hwclock: Use the --debug option to see the details of our search for an access method.
System runs on backports…
![](../../users/profiles/65750.webp)
Tombart
- 2,013
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- 47
6
votes
5 answers
Completely disable Date and Time sync in a Hyper-V VM
No matter what, a Hyper-V virtual machine keeps finding ways to sync time with the host.
I have:
Disabled the time synchronization service
Disabled Windows time
synchronization on the guest machine
mapped time.windows.com to 127.0.0.1 on the hosts…
![](../../users/profiles/273736.webp)
resle
- 189
- 1
- 1
- 9
6
votes
3 answers
Clock is 10% faster than normal
I'm having some strange problem with the clock on my server – it's about 10% faster than normal.
The problem started 2 days ago and I've not done anything special with the server.
I tried to turn of the ntp update by stopping the ntpd daemon.
It…
![](../../users/profiles/107794.webp)
Linus Oleander
- 177
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5
votes
2 answers
How to fix time on NTP server with a lot of machines synchronized by it
I have one NTP server which has a wrong time setting which are 7 hours in the future (timezone was changed after machine shipment, but not the time). The server itself is not synchronized, but only has its local clock. On this server >10 clients…
![](../../users/profiles/126008.webp)
Rick-Rainer Ludwig
- 123
- 1
- 8
5
votes
3 answers
Clock synchronisation on kvm guests
I'm having trouble keeping the system clocks sync'd on a number of kvm guests. I've googled a fair bit, and found a lot of different options, many of which I've tried, to no avail. So here I am.
ntpd is out of the question (the host system runs it…
![](../../users/profiles/19295.webp)
DictatorBob
- 1,614
- 11
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5
votes
3 answers
System clock drifting out of sync with hwclock and ntpd
My current system drifts from the hwclock and ntpd dramatically. I've looked at many forums and posts online and on SF, but haven't found a suitable solution.
Here is my ntpq -pn output:
remote refid st t when poll reach delay …
![](../../users/profiles/63123.webp)
samxli
- 203
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- 11
4
votes
1 answer
TSC missing from available clocksources
Not sure why TSC as a clock source is not available?
cat /sys/devices/system/clocksource/clocksource0/available_clocksource
hpet acpi_pm
The CPU I'm using is Intel Xeon(R) X5570 @ 2.93GHz. The motherboard is Supermicro X8DTU-F. Running CentOS 6.3…
![](../../users/profiles/280949.webp)
sudoer
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4
votes
2 answers
Synchronize time on a private network that must not connect to the Internet
For HIPAA compliance, this network can not be connected to the Internet or to any other network or computer which connects to the Internet.
I've got a small private network comprised entirely of Macs running Mac OS X 10.6. The computers share files…
![](../../users/profiles/31208.webp)
Justin Force
- 338
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- 14
3
votes
1 answer
Compute Engine VM clock runs fast and gains 15 seconds per hour (or about 1 second per each 4 minutes)
I have a 2 vm instances in GCE that do not keep correct time in spite of the server OS being set to sync with NTP every 24 hours. The OS clock gains about 1 second of time every four minutes (or about 15 seconds each hour). One vm instance machine…
![](../../users/profiles/454719.webp)
Ricky
- 31
- 1