CentOS RHEL 7 Chrony Vs NTP (Differences Between ntpd and chronyd).txt

CentOS  RHEL 7  Chrony Vs NTP (Differences Between ntpd and chronyd)

--//翻譯並轉載連結：

CentOS / RHEL 7 : Chrony V/s NTP (Differences Between ntpd and chronyd)

By admin

Chosing between Chrony and NTP

– In RHEL 7 ntpd is replaced by chronyd as the default network time protocol daemon.
– Basic configuration for synchronize time and date is stored in the file /etc/chrony.conf.
– ntpd is still included in yum repository for customers who need to run an NTP service.
– Chrony is a different implementation of the network time protocol (NTP) than the network time protocol daemon (ntpd)
   that is able to synchronize the system clock faster and with better accuracy than ntpd.

--//在RHEL7中，ntpd被chronyd替換為預設的網路時間協議守護程式。
--//同步時間和日期的基本配置儲存在檔案/etc/chrony.conf中。
--//對於需要執行NTP服務的客戶，ntpd仍然包含在Yum儲存庫中。
--//chrony是網路時間協議(NTP)與網路時間協議守護程式(ntpd)的一種不同的實現，它能夠比ntpd更快、更準確地同步系統時鐘。   

Benefits of Chrony include:

1. Faster synchronization requiring only minutes instead of hours to minimize the time and frequency error, which is
   useful on desktops or systems not running 24 hours a day.
--//1.更快的同步只需要幾分鐘而不是幾個小時，以儘量減少時間和頻率誤差，這在桌上型電腦或系統上是有用的，而不是每天24小時執行。

2. Better response to rapid changes in the clock frequency, which is useful for virtual machines that have unstable
   clocks or for power-saving technologies that don't keep the clock frequency constant.
--//2.更好地響應時脈頻率的快速變化，這對於具有不穩定時鐘的虛擬機器或不保持時脈頻率恆定的節電技術是有用的。

3. After the initial synchronization, it never steps the clock so as not to affect applications needing system time to
   be monotonic.
--//3. 在初始同步之後，它從不步進時鐘，以免影響需要系統時間單調的應用程式。   

4. Better stability when dealing with temporary asymmetric delays, for example when the link is saturated by a large
   download.
--//4. 在處理臨時不對稱延遲時，例如當連結被大量下載飽和時，穩定性更好。   

5. Periodic polling of servers is not required, so systems with intermittent network connections can still quickly
   synchronize clocks.
--//5. 不需要定期輪詢伺服器，因此具有間歇性網路連線的系統仍然可以快速同步時鐘。   

When to use chrony

Chrony would be considered a best match for the systems which are frequently suspended or otherwise intermittently
disconnected from a network (mobile and virtual servers etc).

--//對於經常被掛起或以其他方式間歇性地與網路(移動和虛擬伺服器等)斷開連線的系統，時間安排將被視為最佳匹配)。

When to use NTP

The NTP daemon (ntpd) should be considered for systems which are normally kept permanently on. Systems which are
required to use broadcast or multicast IP, or to perform authentication of packets with the Autokey protocol, should
consider using ntpd.

--//對於通常被永久儲存的系統，應該考慮NTP守護程式(ntpd。 需要使用廣播或多播IP或使用Autokey協議執行資料包身份驗證的系統，
--//應考慮使用ntpd。

Filed Under: CentOS/RHEL 7