Time synchronization with the rdate command

The rdate command synchronizes the filer's time with a target computer's time using the UDP time service (typically, UDP port 37). This service is available on most UNIX computers. Check /etc/services and /etc/inetd.conf on the target computer to see whether this service is supported. For detailed information about the protocol that the rdate command uses, see RFC 868.


Note: There is currently no Windows 95 or Windows NT counterpart to the rdate command. If you want to use the rdate command, you must have a UNIX workstation that supports rdate on your filer's network.


When to use the rdate command

You use the rdate command when you need time accuracy only to the second, or when you want to keep your current method of synchronizing time.

Filer clock accuracy

To keep the filer's clock accurate, regularly run the rdate command on the filer with the target machine, a computer that maintains accurate time and that supports the port 37 UDP time service. For example, if the name of the target computer is time_node, enter

rdate time_node

Use of cron jobs to run rdate

A typical scheme is to have a UNIX computer run a periodic cron job that executes the appropriate rdate command on your filer through rsh. The computer and the user (if not root) running the cron job must be in the filer's /etc/hosts.equiv file on the root volume.

cron job example

For example, on the UNIX computer named adminhost, the user named adminuser sets up a cron job to run every day at 3 a.m. It directs the filer named toaster to request a time update from the computer named time_node, which maintains an accurate time and supports the UDP time service.

crontab entry

The crontab entry on the UNIX system is as follows:

0 3 * * * rsh toaster -l root rdate time_node 
Entry in /hosts/equiv file

The /etc/hosts.equiv file on toaster must contain the following line:

adminhost adminuser

The adminhost and time_node host names must be known to the filer.


Copyright © 1999, Network Appliance, Inc. All rights reserved.

Part No. 210-02334
File: routin23.htm
Last updated: 02/24/99 12:15:49