[PVE-User] NTP on PVE8...

[PVE-User] NTP on PVE8...

[Marco Gaiarin]

Running 'pve7to8' i've catch:

 INFO: Checking for supported & active NTP service..
 WARN: systemd-timesyncd is not the best choice for time-keeping on servers, due to only applying updates on boot.
   While not necessary for the upgrade it's recommended to use one of:
     * chrony (Default in new Proxmox VE installations)
     * ntpsec
     * openntpd

This is indeed mostly true, and in a cluster using a NTP daemon is a must.
No doubt on that.


But for a standalone server, systemd-timesyncd seems sufficient to me; and
surely NOT 'only applying updates on boot': systemd-timesyncd sync time at
regilar interval!

       PollIntervalMinSec=, PollIntervalMaxSec=
           The minimum and maximum poll intervals for NTP messages. Polling starts at the minimum poll interval, and is adjusted within the specified limits in response to received
           packets.

           Each setting takes a time span value. The default unit is seconds, but other units may be specified, see systemd.time(5).  PollIntervalMinSec= defaults to 32 seconds and
           must not be smaller than 16 seconds.  PollIntervalMaxSec= defaults to 34 min 8 s (2048 seconds) and must be larger than PollIntervalMinSec=.


Here still using systemd-timesyncd for my standalone servers...

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Re: [PVE-User] NTP on PVE8...

[Alwin Antreich via pve-user]

[-- Attachment #1: Type: message/rfc822, Size: 5582 bytes --]

From: "Alwin Antreich" <alwin@antreich.com>
To: gaio@lilliput.linux.it
Cc: "Proxmox VE user list" <pve-user@lists.proxmox.com>
Subject: Re: [PVE-User] NTP on PVE8...
Date: Mon, 19 Aug 2024 14:57:52 +0000
Message-ID: <6f37f0399dca2a68bf3129aefc8a5843799654bd@antreich.com>

Hi Marco,



August 19, 2024 at 11:00 AM, "Marco Gaiarin" <gaio@lilliput.linux.it> wrote:



> 
> Running 'pve7to8' i've catch:
> 
>  INFO: Checking for supported & active NTP service..
>  WARN: systemd-timesyncd is not the best choice for time-keeping on servers, due to only applying updates on boot.
>  While not necessary for the upgrade it's recommended to use one of:
>  * chrony (Default in new Proxmox VE installations)
>  * ntpsec
>  * openntpd
> 
> This is indeed mostly true, and in a cluster using a NTP daemon is a must.
> No doubt on that.
> 
> But for a standalone server, systemd-timesyncd seems sufficient to me; and
> surely NOT 'only applying updates on boot': systemd-timesyncd sync time at
> regilar interval!
> 
>  PollIntervalMinSec=, PollIntervalMaxSec=
>  The minimum and maximum poll intervals for NTP messages. Polling starts at the minimum poll interval, and is adjusted within the specified limits in response to received
>  packets.
> 
>  Each setting takes a time span value. The default unit is seconds, but other units may be specified, see systemd.time(5). PollIntervalMinSec= defaults to 32 seconds and
>  must not be smaller than 16 seconds. PollIntervalMaxSec= defaults to 34 min 8 s (2048 seconds) and must be larger than PollIntervalMinSec=.
> 
systemd-timesyncd only uses one server to update its time, which can lead to time jumps when this NTP can't be accessed reliably. NTPs (eg. ntpd/chrony) are usually using 3+ servers to calculate a mean time and compensate for jitter and other delays. This allows to keep the time more stable and especially helps when Ceph or HA is enabled. ;)

I do recommend chrony for servers (physical or virtual).

Cheers,
Alwin

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Re: [PVE-User] NTP on PVE8...

[Marco Gaiarin]

Mandi! Alwin Antreich
  In chel di` si favelave...

> systemd-timesyncd only uses one server to update its time, which can lead to
> time jumps when this NTP can't be accessed reliably. NTPs (eg. ntpd/chrony) are
> usually using 3+ servers to calculate a mean time and compensate for jitter and
> other delays.

systemd-timesyncd does not use one server, have also fallback one (or use
round robin); surely 'mean/compensate' is better then fallback and round
robin, but...

> This allows to keep the time more stable and especially helps
> when Ceph or HA is enabled. ;)

...clearly i'm speaking of standalone server or non-HA, non-Ceph clusters!


Anyway, the statement:

>> WARN: systemd-timesyncd is not the best choice for time-keeping on servers, due to only applying updates on boot.

it is not true: i suggest to remove at least 'due to only applying updates on boot'.


(clearly, for future 'pve8to9' scripts... ;-)

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Re: [PVE-User] NTP on PVE8...

[DERUMIER, Alexandre]

basically, systemd-timesync is a simple pool sntp client  

https://github.com/systemd/systemd/blob/v213/NEWS#L5

A new "systemd-timesyncd" daemon has been added for
          synchronizing the system clock across the network. It
          implements an SNTP client. In contrast to NTP
          implementations such as chrony or the NTP reference server
          this only implements a client side, and does not bother with
          the full NTP complexity, focusing only on querying time from
          one remote server and synchronizing the local clock to
          it. Unless you intend to serve NTP to networked clients or
          want to connect to local hardware clocks this simple NTP
          client should be more than appropriate for most
          installations. The daemon runs with minimal privileges, and
          has been hooked up with networkd to only operate when
          network connectivity is available. The daemon saves the
          current clock to disk every time a new NTP sync has been
          acquired, and uses this to possibly correct the system clock
          early at bootup, in order to accommodate for systems that
          lack an RTC such as the Raspberry Pi and embedded devices,
          and make sure that time monotonically progresses on these
          systems, even if it is not always correct. To make use of
          this daemon a new system user and group "systemd-timesync"
          needs to be created on installation of systemd.


Ntp implement incremental time increase/decrease. You really want that
(not big time jump), if you want stable virtualisation (Hello windows
BSOD).


Redhat use chrony on rhel server distro.




-------- Message initial --------
De: Marco Gaiarin <gaio@lilliput.linux.it>
Répondre à: Proxmox VE user list <pve-user@lists.proxmox.com>
À: pve-user@lists.proxmox.com
Objet: Re: [PVE-User] NTP on PVE8...
Date: 19/08/2024 17:50:29

Mandi! Alwin Antreich
  In chel di` si favelave...

> systemd-timesyncd only uses one server to update its time, which can
> lead to
> time jumps when this NTP can't be accessed reliably. NTPs (eg.
> ntpd/chrony) are
> usually using 3+ servers to calculate a mean time and compensate for
> jitter and
> other delays.

systemd-timesyncd does not use one server, have also fallback one (or
use
round robin); surely 'mean/compensate' is better then fallback and
round
robin, but...

> This allows to keep the time more stable and especially helps
> when Ceph or HA is enabled. ;)

...clearly i'm speaking of standalone server or non-HA, non-Ceph
clusters!


Anyway, the statement:

> > WARN: systemd-timesyncd is not the best choice for time-keeping on
> > servers, due to only applying updates on boot.

it is not true: i suggest to remove at least 'due to only applying
updates on boot'.


(clearly, for future 'pve8to9' scripts... ;-)


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Re: [PVE-User] NTP on PVE8...

[Olivier Benghozi]

Seriously, systemd-timesyncd is fine for clients, not for servers. It's
just a very simple SNTP daemon.
It must be said too that once you start using chrony, you just throw away
all those other stuffs (and happily forget all the various historic issues
and problems you experienced in the past with ntpd).


Le lun. 19 août 2024 à 18:42, DERUMIER, Alexandre <
alexandre.derumier@groupe-cyllene.com> a écrit :

> basically, systemd-timesync is a simple pool sntp client
>
> Ntp implement incremental time increase/decrease. You really want that
> (not big time jump), if you want stable virtualisation (Hello windows
> BSOD).
>
> Redhat use chrony on rhel server distro.
>
>
> -------- Message initial --------
> De: Marco Gaiarin <gaio@lilliput.linux.it>
> Répondre à: Proxmox VE user list <pve-user@lists.proxmox.com>
> À: pve-user@lists.proxmox.com
> Objet: Re: [PVE-User] NTP on PVE8...
> Date: 19/08/2024 17:50:29
>
>
> Anyway, the statement:
>
> > > WARN: systemd-timesyncd is not the best choice for time-keeping on
> > > servers, due to only applying updates on boot.
>
> it is not true: i suggest to remove at least 'due to only applying
> updates on boot'.
>
>
> (clearly, for future 'pve8to9' scripts... ;-)
>

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