Questions tagged [clock-synchronization]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0 votes
3 answers
91 views

No info found about `ethtool -T` output?

Nowhere I can find such info, to interpret the following number: PTP Hardware Clock: 1 Most documentation I can find (e.g. from RedHat it shows 0). What does it mean?
jaques-sam's user avatar
0 votes
1 answer
156 views

How can I verify if time is set correctly on server in my bash script?

I'm working on ultimate backup script for very important server. My script already: creates a backup verifies copied file(-s) verifies gz archive compares MD5 on local and remote after sending file ...
Kamil's user avatar
  • 157
0 votes
1 answer
614 views

How can the local time clock of a server become the NTP time source in a network?

I want to make a the local te clock in a Stratum 1 server be the network time source for my network (I don't want a Stratum 0 server with the antenna). How may I set this up in a network? Is there a ...
Baldovín Cadena Mejía's user avatar
1 vote
1 answer
403 views

How "real" is the POSIX clock in a virtual machine?

Introduction: Time is OS like Linux is typically derived from a clock chip (RTC), or maintained by software using either periodic interrupts or some hardware registers (e.g. CPU's TSC cycle counter) ...
U. Windl's user avatar
  • 366
0 votes
1 answer
936 views

Cannot change NTP Time Source on a 2012 R2 DC Server

So I have seen dozens of people with this issue on various websites and forums, but here I am asking again. No matter what I try so far, nothing has fixed the issue which I will describe below in as ...
ksrobinson's user avatar
0 votes
2 answers
529 views

Is there a way to keep server times in sync to the millisecond, globally?

I'm working on a project where I need to keep server times in sync, to the millisecond. There are servers in the UK, US and Asia amongst other countries, and at the moment someone is manually having ...
Professor of programming's user avatar
1 vote
1 answer
554 views

Incorrect PTP timestamps [closed]

I have trouble syncing to Linux systems using PTP. Setup: Two PCBs with a BegleCore module and a DP83640 PHY are connected with each other over Ethernet. One board should act as the PTP master, the ...
11011100's user avatar
  • 111
0 votes
1 answer
143 views

ntpdate succeeds but ntpq fails against Windows DC

DC: Server 2019 Client: TrueNAS https://docs.microsoft.com/en-US/troubleshoot/windows-server/identity/configure-authoritative-time-server for step 3, the DC is configured to be an NTP server and is ...
Tyler Montney's user avatar
1 vote
1 answer
3k views

How to Set Up Time Synchronization with NTP on Ubuntu 20.04.1 LTS

After updating the base system with the latest available packages: apt-get update -y and root@localhost:~# timedatectl Local time: Wed 2021-01-06 08:03:11 UTC Universal time:...
Fèlix Boniquet Pelfort's user avatar
0 votes
1 answer
2k views

DC NTP not syncing and Local CMOS Clock issue

I've configured my DC (Domain Controller; Windows 2016) as described here to get his time from my Sophos-UTM. So i configured the GPO as described there. But after that and a restart of the server i ...
Opa114's user avatar
  • 113
0 votes
1 answer
244 views

Problems with chronyd Centos 7 all updates applied

I have an email server running on top of CentOS7. This is a new server and has been in production for 2 days. It seems that chronyd is losing it's connection to the ntp servers that it contacts at ...
tgz's user avatar
  • 3
1 vote
1 answer
905 views

Prevent VM clock running faster than it should

I have a unRAID 6.6.5 server with perfectly correct time and multiple Linux VMs which used to be perfectly synced too. I rebooted one of my VM and suddenly the clock goes twice as fast as the hwclock. ...
dan's user avatar
  • 83
3 votes
1 answer
211 views

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 ...
Ricky's user avatar
  • 31
8 votes
3 answers
7k views

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 ...
Daniel R.'s user avatar
  • 211
11 votes
1 answer
65k views

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 ...
Orelsanpls's user avatar
1 vote
1 answer
881 views

How to have WSL think it is in the past? [closed]

I am developing PHP/Apache/MySQL based code on my Windows 10 laptop via Windows Subsytem For Linux. I am working on some code that is time related. It has a mix of PHP date commands, and MySQL "NOW()"...
Hippyjim's user avatar
  • 211
3 votes
1 answer
829 views

AWS EC2 with huge clock drift at boot

We have an Amazon EC2 CentOS 7.5 instance whose clock, at boot, is always 35 days late. Yes, you read it correctly. That's a hell of a drift. [root@myec2 ~]# ntpd -gqn ntpd: time set +2937270.012860s ...
dr_'s user avatar
  • 1,085
3 votes
0 answers
928 views

NTP 'reach' resetting, wrong refid of remote ntp server, and high jitter

I've got a remote unmanned server that's been exhibiting some extremely strange clock/NTP behavior lately. Symptoms: Very high jitter ntpq -pn returns: A resetting 'when' count of back to 1, even ...
EnemyBagJones's user avatar
-5 votes
1 answer
319 views

Time on Windows servers out and won't stay corrected

I have a bunch of windows servers that are VM's running on a group of hypervisors, all in a domain environment. Its a mix of Server 2012 R2 and Server 2016 For some reason the clock is out by about 7 ...
John's user avatar
  • 541
6 votes
5 answers
12k views

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 ...
resle's user avatar
  • 189
0 votes
1 answer
868 views

/sbin/hwclock --utc --systohc not working on AWS EC2 under Ubuntu

I'm in the process of moving some servers to AWS. One problem I'm encountering is that my script to synchronize the time using ntpdate and then write that time to the hwclock is failing. When the ...
Stephen Ostermiller's user avatar
2 votes
0 answers
871 views

Chrony reporting system time slower than NTP and growing

I have chrony running on several of my instances. Unfortuantely, on one of them, it keeps reporting that the system time is slower than NTP time. This number of seconds keeps growing at a rate of ...
checklist's user avatar
  • 121
0 votes
0 answers
126 views

How to read VMware interrupt backlog?

The VMware document titled "Timekeeping in VMware Virtual Machines" have the following referente to the issues with the time drift: If the virtual machine is running too slowly, perhaps as a result ...
rfmoz's user avatar
  • 772
7 votes
3 answers
36k views

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 ...
Tombart's user avatar
  • 2,143
3 votes
2 answers
7k views

FreeBSD: how to syncronize the system clock with the hardware clock in bash?

I am writing a script that synchronizes the system clock with the hardware clock (aka RTC, or CMOS clock) assuming that no Network Time Protocol (NTP) daemon is running. I am running in a virtual ...
Lilás's user avatar
  • 223
3 votes
2 answers
2k views

RTC time is going totally wrong after a few minutes (Ubuntu 16.04 + Hyper-V)

My RTC time on my Ubuntu 16.04 is going crazy. After a few minutes the RTC time is going totaly wrong. The strange thing is, if I disable NTP Service (timedatectl set-ntp false and service ntp stop) ...
Jerico's user avatar
  • 31
0 votes
0 answers
1k views

When to change current_clocksource

I am running an Ubuntu 16.04 machine on a M4.xlarge in AWS EC2. I was reading about some of the performance tuning that Netflix did for their EC2 machines (link: http://www.brendangregg.com/blog/2015-...
jamesatha's user avatar
  • 133
2 votes
0 answers
2k views

How to configure hwclock to UTC on Redhat Linux?

I have linux redhat machine # more /etc/redhat-release Red Hat Enterprise Linux Server release 5.11 (Tikanga) I want to change the hwclock to UTC time So I perform little test as # date -u Tue ...
dandan's user avatar
  • 1,081
8 votes
2 answers
7k views

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/...
dandan's user avatar
  • 1,081
1 vote
0 answers
358 views

Preventing system clock from auto-updating in Windows Server 2012

I'm working on a project right now where as part of testing I have to move the system clock to far-off future dates. There are two servers involved in the project: an app server and a database server. ...
John Clifford's user avatar
1 vote
1 answer
1k views

NTP synchronized clock alongside the system clock

Does NTP daemon(ntpd) provide some sort of virtual clock that it disciplines and serves, but not touch the system clock? Goal: On a realtime Linux OS, have a NTP synchronized clock alongside of the ...
Vikyboss's user avatar
  • 121
1 vote
0 answers
211 views

RTC/UTC was innacurate on MySQL (MariaDB) server. I fixed it - was that bad?

I'm pinch hitting as an admittedly green server admin. I installed a bunch of security patches on a MariaDB server that had an incorrectly configured repo (not by me) and wasn't getting patches for a ...
bendodge's user avatar
  • 156
5 votes
2 answers
2k views

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 ...
Rick-Rainer Ludwig's user avatar
2 votes
2 answers
2k views

How accurate can we get computer clocks synchronized in a local network of any number of computers?

In the past, I have seen that most of my computer on my local network don't really have the same time within up to 1 second or so. So I wanted to make sure that it would be possible for a stack of ...
Alexis Wilke's user avatar
  • 2,200
0 votes
2 answers
7k views

NTP service stopped in centos7.1 linux machine

In our 3 linux boxes centos 7.1, we saw below messages in the logs and then ntpd service got stopped since the offset is more than 1000s. systemd: Time has been changed ntpd[2626]: 0.0.0.0 0617 07 ...
xrkr's user avatar
  • 413
0 votes
1 answer
363 views

How to synchronize the time in Debian6 server? We have 30 min delay in our VMs

I can't have the correct time in our servers. We get always the same delay in the three of them (they are VM on the same server). We use ntp to have our date always synchronized· The main server ...
Emilio Nicolás's user avatar
4 votes
1 answer
3k views

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 ...
sudoer's user avatar
  • 43
1 vote
1 answer
921 views

Why is clock synchronization on servers difficult?

See: Clock synchronization quality on Windows Azure? This is not meant as a rant, it is just curiosity. Is a computer really drifting more than a second in a single day? I can barely imagine that. ...
Dirk Boer's user avatar
  • 485
3 votes
1 answer
659 views

system clock skewing backwards 112 seconds

I'm troubleshooting a problem on one of my NTP servers. This server seems to defy logic, and I'm at my wits end trying to troubleshoot it. Roughly every 162 seconds, the system clock reverts to (...
ben's user avatar
  • 191
14 votes
3 answers
14k views

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 ...
Nils Toedtmann's user avatar
-1 votes
1 answer
131 views

ntp daemon seems useless and why my server date time is far behind my local time

I've installed ntp daemon in ubuntu to sync my date time with the network time. Now my time on the server is 11:00 while my PC date/time is 19:30. Now all my transactions date/times are logged ...
Alireza's user avatar
  • 583
27 votes
3 answers
52k views

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 ...
user avatar
0 votes
1 answer
837 views

Windows server and AWS clock synchronization

I have a Windows 7 computer that communicates with Amazon Web Servers (S3, SES). This server uses windows internet time for clock synchronization time.windows.com. On my linux machines I ran into ...
The Internet's user avatar
2 votes
0 answers
713 views

Hardware Clock (RTC) Stuck / Will Not Increment

After we rebooted one of our servers (RHEL), we noticed that it would hang when entering GRUB. The problem was the countdown in GRUB (Booting in 5... 4......) was not counting down, and was stuck at ...
Tanaki's user avatar
  • 131
1 vote
2 answers
603 views

Cent OS 6 clock 3 minutes 35 seconds in the future

I run Cent os 6 64 bit on linode. server (incorrect): date Thu Aug 29 11:41:00 BST 2013 client (correct): date Thu Aug 29 11:37:25 BST 2013 As you can see the server clock is in ...
Code Review Doctor's user avatar
1 vote
0 answers
1k views

Update clock on virtualbox virtual machine with cent os from host

I have a virtual machine, with cent os installed, and everytime I sleep the host computer, the clock of the VM goes out of sync. I would like it to pick up the current time from virtualbox - which I ...
Billy Moon's user avatar
  • 1,437
-2 votes
1 answer
193 views

System Time Synchronization Procedure [closed]

I am looking for procedure which I can execute in cron to synch the system time in clustered servers. Can any of the experienced SME's please help?
Pete Ekanem's user avatar
2 votes
1 answer
475 views

How to backdate a domain-connected workstation?

I need to verify some test cases by backdating my system. How to do this?
O.O's user avatar
  • 349
6 votes
3 answers
3k views

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 ...
Linus Oleander's user avatar
0 votes
3 answers
286 views

Is TimeSync still needed on Windows Server 2008?

I've always used TimeSync on my servers. With Windows' built in internet time updating, should I remove TimeSync? I've never turned off windows time updating even with TimeSync - what is the best ...
Neal's user avatar
  • 399