[PVE-User] Chrony?!

[Stefan Radman]

Hi Marco

Quoting from "chrony vs. systemd-timesyncd – What are the differences and use cases as NTP clients? <https://newbedev.com/chrony-vs-systemd-timesyncd-what-are-the-differences-and-use-cases-as-ntp-clients>"

systemd-timesyncd is a client-only implementation of the SNTP protocol (RFC4330).
It can only synchronize to a single source, can not serve as a time source, typically steps the system time and is less accurate.

chrony is a full client and server mode implementation of the NTPv4 protocol (RFC5905).
chrony can synchronize to multiple sources, slowly adjusts system time and is typically more accurate.

With chrony you can synchronize your cluster nodes to pool.ntp.org <http://pool.ntp.org/> and to each other, making your cluster a very stable time reference.
See example below. You can’t do that with systemd.

Stefan

root at pve1:~# for node in pve1 pve2 pve3; do ssh $node 'hostname && cat /etc/chrony/sources.d/peer.sources && chronyc sources'; done
pve1
# peer with cluster neighbors
peer pve2.home.arpa
peer pve3.home.arpa
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^- nu.binary.net                 2   6   377   101   -844us[-1017us] +/-   54ms
^? 168.119.4.163.polisystem>     3   8     2   350  +1410us[ +889us] +/-  130ms
^* ntp1.glypnod.com              2   7   377    34   -911us[-1020us] +/-   21ms
^+ t2.time.gq1.yahoo.com         2   7   377    36   -124us[ -233us] +/-   27ms
=+ pve2.home.arpa                4   6   377   398  +2193us[+1409us] +/-   39ms
=+ pve3.home.arpa                5   6   377   120   +909us[ +737us] +/-   20ms
pve2
peer pve1.home.arpa
peer pve3.home.arpa
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^- 156.67.164.186                3   6   377    40  -1227us[-1227us] +/-  124ms
^- fastmirror.pp.ua              2   6   377    37  -2191us[-2191us] +/-   94ms
^+ c-73-239-136-185.hsd1.wa>     3   6   377    40  +2131us[+2131us] +/-   38ms
^- ntp1.karneval.cz              2   6   377   102  +1068us[+1381us] +/-  106ms
=* pve1.home.arpa                3   6   377    45   -761us[ -447us] +/-   20ms
=+ pve3.home.arpa                4   6   377   263   -760us[ +152us] +/-   40ms
pve3
# peer with cluster neigbors
peer pve1.home.arpa
peer pve2.home.arpa
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^- fastmirror.pp.ua              2   6   377    40  -2083us[-2054us] +/-   93ms
^+ c-73-239-136-185.hsd1.wa>     3   6   377    43  +1884us[+1912us] +/-   38ms
^- 156.67.164.186                3   6   377    42   -822us[ -794us] +/-  125ms
^- ntp1.karneval.cz              2   6   377    42  +2503us[+2532us] +/-  108ms
=+ pve1.home.arpa                3   6   375    52   -698us[ -677us] +/-   20ms
=* pve2.home.arpa                4   6   377    28    -14us[  +24us] +/-   20ms


> On Oct 24, 2021, at 11:27, Marco Gaiarin <gaio at lilliput.linux.it> wrote:
> 
> 
> I've just installed a PVE7; impressive, thanks.
> 
> 
> But i've found that Chrony get installed; looking at changelog/roadmap:
> 
> 	https://pve.proxmox.com/wiki/Roadmap#Proxmox_VE_7.0
> 
> 	Time Synchronization:
> 	 Due to the design limitations of systemd-timesync, which make it problematic for server use, new installations will install chrony as the default NTP daemon.
> 	 If you upgrade from a system using systemd-timesyncd, it's recommended that you manually install either chrony, ntp or openntpd.
> 
> But looking at wiki, still systemd-timesyncd is cited:
> 
> 	https://pve.proxmox.com/wiki/Time_Synchronization
> 
> 
> What are these «problematic for server use» limitation? Someone can point to
> some clue?
> 
> 
> Thanks.
> 
> -- 
>  Il backup è quella cosa che andava fatta prima.
> 					(Proverbio Cinese, Simone Aliprandi)
> 
> 
> 
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