Redhat7:ntp vs Chrony

Ntp Vs Chony

The biggest issue with NTP is that it can take a relatively long time to adjust their clocks using ntp to an accurate time if they are not permanently powered on. On a warm reboot NTP can take anywhere from 10 seconds to several hours depending on the accuracy required.

This is due to ntp making a large number of small corrections based on drift and offsets, which themselves can be off due to out side influences such as temperatures.

Chrony has been designed to reduce the time it takes to adjust the system clock.

Differences between the two Services

The algorithm used in the two services is the major difference and this allow chrony to achieve better results than ntp in certain situations:

• where the external time references are only available intermittently.
• where the networks are congested
• where the clock needs to be synced faster with better accuracy
• where there are sudden changes to the rate of the clock, chrony will react faster
• by default chrnony will not step the clock after the initial sync at start up
• Chrony can adjust the clock rate in a wider range, allowing it to deal with a broken clock

Functional Differences

• chrony can provide support for isolated networks with manual entry as the only form of correction
• chrony can also calcuate the rate of gain or loss of the real-time or hardware clock

• ntp fully supports ntp v4
• ntp includes a bigger range of drivers for reference clocks