Synchronizing the system time

About synchronizing system time

You can use the timed daemon to automatically keep the system time for your storage system synchronized with a time server. Using this feature is advised, because problems can occur when the storage system clock is inaccurate.

About time servers

To automatically keep your storage system time synchronized, you need the name of at least one time server. For best results, supply the name of more than one time server in case one becomes unavailable.

About the protocols

There are two protocols you can use for time synchronization: SNTP and rdate.

SNTP (Simple Network Time Protocol) is more accurate; therefore, it is the preferred protocol. You can get a list of public NTP (Network Time Protocol) time servers (used for SNTP) from the NTP.Servers Web at http://ntp.isc.org/bin/view/Servers/WebHome.

If you can't access an SNTP server, you can use rdate. Many Unix servers can function as an rdate server; see your system administrator to set up or identify an rdate server in your environment.

Synchronizing system time

To set the timed daemon to keep the storage system time synchronized with the time server, complete the following steps.

Step	Action
1	If the current time for the storage system is not fairly close to the actual time, use the date command to set the system time to the correct time. For more information about setting the system clock, see Setting the system date and time.
2	At the command line, set the appropriate `timed` options using the `options` command. At a minimum, you must set the `proto` option to use either `sntp` or `rdate` (`sntp` is the preferred protocol), and set the `servers` option to at least one valid time server for the protocol you select. For more information about the protocols, see About the protocols. For more information about the `timed` options, see the na_options(1) man page or About the timed options.
3	Enter the following command to enable the `timed` daemon: options timed.enable on

Step

Action

If the current time for the storage system is not fairly close to the actual time, use the date command to set the system time to the correct time.

For more information about setting the system clock, see Setting the system date and time.

At the command line, set the appropriate timed options using the options command.

At a minimum, you must set the proto option to use either sntp or rdate (sntp is the preferred protocol), and set the servers option to at least one valid time server for the protocol you select.

For more information about the protocols, see About the protocols. For more information about the timed options, see the na_options(1) man page or About the timed options.

Enter the following command to enable the timed daemon:

options timed.enable on

About the timed options

The following table summarizes the available timed options and their default value. For more detailed information on the timed options, see the na_options(1) man page.

Timed option	Function	Allowable values	Default value
`enable`	Enables time synchronization.	`on` `off`	`on`
`log`	Specifies whether time changes should be logged to the console.	`on` `off`	`off`
`max_skew`	Specifies the maximum allowable skew between the system time and the time server time. If the skew exceeds this value, synchronization does not occur.	ns nm nh	`30m`
`proto`	Specifies the protocol used to synchronize the time.	`rtc` (internal Real-Time Clock) `rdate` RFC 868 `sntp` RFC 2030 (preferred)	`rtc`
`sched`	Specifies the timed synchronization schedule.	`hourly` `multihourly` `daily` `custom`	`1h` (hourly)
`servers`	Specifies up to five time servers used by the timed daemon.	Example `times1,times2.ntap.com,10.15.46.92`	null string
`window`	Specifies a window of time around the synchronization time when the synchronization can occur.	ns nm	`0s`

Example clock synchronization

The following example configures timed to use the SNTP protocol with the default hourly synchronization schedule.

filer1> date

Thu Dec  9 13:49:10 PST 2004

filer1> options timed.proto ntp

filer1> options timed.servers pool.ntp.org,10.15.46.92

filer1> options timed.enable on