[SailfishDevel] Warning: File `Makefile' has modification time 0.51 s in the future

[David Greaves]

On 15/04/14 07:07, christopher.lamb at thurweb.ch wrote:
> Hi Thomas
> 
> Earlier this year in addition to my normal day job I took over responsibility
> for a server farm of over 50 servers both real and virtual. Their clocks, system
> and hardware were all over the place. This lead to strange knock on effects,
> like Samba not being able to authenticate users via SSSD / LDAP.
> 
> In order to git the clocks under control again I was forced to find out much
> more about clock-skew {1} and NTP then I cared for. As a result I can be very
> boring on the subject. 8-)
> 
> While ntpdate is a valid pragmatic workaround, it remains a workaround, as a
> properly configured ntp daemon should automatically keep your system clock in
> sub millisecond sync. Be aware also that NTDATE is deprecated {2}. Instead you
> should use ntpd -gq

Personally I think you should use a virtualisation specific solution to time
sync if possible - it tends to cope better with virt specific issues like
suspend and migrate. eg VMs running on laptops. In this case the VM may not even
know that it was suspended since the virt layer does it, not VM pm layer and
hence cannot trigger special-case timesync handling.

Running ntp on all guests is required in some situations though (eg older xen).

Happy to hear any counter-arguments though

nb - in farm situations this also means that you simply run ntp on the physical
hosts and that's one less config pita on the guests :)

> However if the time is already "too far off" the NTD may never be able to catch
> up (as normally it only makes small jumps {3), or even give up altogether.
> 
> When I encountered a server with clock(s) "way off" I used the set of commands
> below to get it back in line.
> 
> hwclock --show
> date
> service ntpd stop
> ntpd -gq
> hwclock --systohc --localtime
> service ntpd start
> hwclock --show
> date
> 
> After that, if NTPD is properly configured, then NTP should be able to keep the
> server's system clock in line.
> 
> HtH
> 
> Chris
> 
> 
> {1} the root of all evil
> {2} http://support.ntp.org/bin/view/Dev/DeprecatingNtpdate
> {3} by my measurements about 1.7 mins per day
> 
> 
> Zitat von "Thomas Tanghus" <thomas at tanghus.net>:
> 
>> On Monday 14 April 2014 14:49 Chris Walker wrote:
>>> I installed the ntp client and it now picks up network time. I'm
>>> assuming therefore that there is some time 'slip' between the host
>>> machine and VBox.
>>
>> I had the same problem and now run ntpdate from cron.daily. Turns out my PCs
>> clock loses ~5 seconds(sic!) for every 24h :(
>>
>> -- 
>> Med venlig hilsen / Best Regards
>>
>> Thomas Tanghus
>> _______________________________________________
>> SailfishOS.org Devel mailing list
>>
> 
> 
> 
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