NAME

ntp.drift − Network Time Protocol (NTP) drift file

DESCRIPTION

When the NTP daemon (xntpd) is first started, it computes the error in the intrinsic frequency of the clock on the computer it is running on.  This process usually takes about a day or two after the daemon is started to compute a good estimate of this (and it needs a good estimate to synchronize closely to its server).  Once the initial value is computed, it will change only by relatively small amounts during the course of continued operation. 

The driftfile declaration should always be included in the ntp.conf file.  This provides xntpd with complete path name to a file in which it can store the current value of the frequency error.  That way, if the daemon is stopped and restarted, it can reinitialize itself to the previous estimate without spending time recomputing the frequency estimate. 

The ntp.drift file contains one line with the following format: freq_offset flag

freq_offset
Specifies the nominal frequency offset.  DO NOT modify this field.

flagSpecifies the method used to improve system clock accuracy. 

0Specifies that xntpd runs a Phase-Locked Loop (PLL) algorithm to keep synchronized with other hosts.  This is the default. 

1Specifies the use of the PLL algorithm in the kernel.  This requires the NTP_TIME kernel option.  After the option is configured in the kernel, edit the ntp.drift file and change the flag value to 1. 

See System Administration for information on the NTP_TIME kernel option. 

FILES

/etc/ntp.drift
Conventional name of the drift file

RELATED INFORMATION

Commands: ntpdate(8), ntpq(8), xntpd(8), xntpdc(8)

Files: ntp.conf(4)

Network Administration, System Administration