From: Alwin Antreich via pve-user <pve-user@lists.proxmox.com>
To: gaio@lilliput.linux.it
Cc: Alwin Antreich <alwin@antreich.com>,
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 [thread overview]
Message-ID: <mailman.313.1724079504.302.pve-user@lists.proxmox.com> (raw)
In-Reply-To: <46ebpk-rqm.ln1@leia.lilliput.linux.it>
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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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next prev parent reply other threads:[~2024-08-19 14:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-19 9:00 Marco Gaiarin
2024-08-19 14:57 ` Alwin Antreich via pve-user [this message]
[not found] ` <6f37f0399dca2a68bf3129aefc8a5843799654bd@antreich.com>
2024-08-19 15:50 ` Marco Gaiarin
2024-08-19 16:34 ` DERUMIER, Alexandre
2024-08-19 18:45 ` Olivier Benghozi
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