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Questions tagged [clock-synchronization]

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1
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1answer
74 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. ...
3
votes
1answer
50 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 ...
5
votes
3answers
329 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 ...
0
votes
1answer
1k 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 ...
-1
votes
1answer
55 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()"...
3
votes
1answer
240 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 ...
2
votes
0answers
202 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 ...
-5
votes
1answer
35 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 ...
4
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3answers
2k 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 ...
0
votes
1answer
281 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 ...
2
votes
0answers
417 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 ...
-1
votes
0answers
107 views

Why do linux services freeze and system clock reset when they unfreeze?

We have a device running a process that makes heavy use of networking, and we're finding that there are times (never consistent) when it, and other system processes, freeze for about 22 minutes. ...
0
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0answers
51 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 ...
3
votes
2answers
9k 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 ...
2
votes
2answers
2k 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 ...
2
votes
1answer
791 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) ...
0
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0answers
802 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-...
2
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0answers
480 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 ...
6
votes
2answers
2k 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/...
1
vote
0answers
55 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. ...
1
vote
1answer
443 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 ...
1
vote
0answers
66 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 ...
4
votes
2answers
939 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 ...
1
vote
2answers
1k 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 ...
0
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2answers
3k 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 ...
0
votes
1answer
263 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 ...
3
votes
1answer
1k 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 ...
1
vote
1answer
737 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. ...
3
votes
1answer
366 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 (...
10
votes
2answers
8k 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 systems that ...
-1
votes
1answer
96 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 ...
18
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3answers
30k 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 ...
0
votes
1answer
702 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 ...
2
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0answers
511 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 ...
1
vote
2answers
427 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 ...
1
vote
0answers
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 ...
-2
votes
1answer
160 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?
2
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1answer
365 views

How to backdate a domain-connected workstation?

I need to verify some test cases by backdating my system. How to do this?
6
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3answers
2k 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 ...
0
votes
3answers
260 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 ...
3
votes
2answers
50k views

WS2008 NTP - Using time.windows.com,0x9 - Time always skewed forwards

I have a domain controller configured to use time.windows.com (with 0x09 flags set). I've noticed that frequently the systems' clock is fast - it varies from 10 minutes to even 45 minutes. I always ...
0
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2answers
456 views

Virtualizing NTP server [duplicate]

Possible Duplicate: What are the limits of running NTP servers in virtual machines? I was wondering if virtualizing NTP is okay. I have a VMware ESXi 5.0 box, and I want to virtualize my router ...
2
votes
2answers
602 views

SLES guest on HyperV: high CPU usage vs. accurate time keeping

Here is the issue: SLES 10 SP1 guest is running on HyperV. I need accurate timekeeping on this box, so I have applied these kernel parameters (which were proven to work on other identical SLES 10 SP1 ...
3
votes
4answers
3k views

VMware: How to keep time in guest after suspend

I have Gentoo installed as guest OS. I have hardware clock synced with host system, but the clock of OS tend to be wrong after suspend. The only solution I find out is run hwclock -s frequently via ...
8
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6answers
3k views

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 ...
4
votes
2answers
667 views

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 ...
4
votes
3answers
9k views

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 ...
3
votes
2answers
395 views

periodically overridding NTP for simulation purposes

I have this situation: NTP is used to sync time on a set of Windows 7 and Server 2008 machines. Nothing out of the ordinary about this. periodically on this system, the time needs to be changed for ...
2
votes
4answers
6k views

NTP failing to update

I am attempting to use ntp on the server. Checking ps the ntpd process seems to be running: ntpd -u ntp:ntp -p /var/run/ntpd.pid -g However the time is not being corrected, any ideas? The drift is ...
5
votes
3answers
5k views

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 ...