Sun Java System Application Server Enterprise Edition 8.1 2005Q2 High Availability Administration Guide

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## Synchronizing System Clocks

You must synchronize clocks on HADB hosts, because HADB uses time stamps based on the system clock. HADB uses the system clock to manage timeouts and to time stamp events logged to history files. For troubleshooting, you must analyze all the history files together, since HADB is a distributed system. So, it is important that all the hosts’ clocks be synchronized

Do not adjust system clocks on a running HADB system. Doing so can cause problems in the operating system or other software components that can in turn cause problems such as hangs or restarts of HADB nodes. Adjusting the clock backward can cause some HADB server processes to hang as the clock is adjusted.

To synchronize clocks:

- On Solaris, use `xntpd` (network time protocol daemon).

- On Linux, use `ntpd`.

- On Windows, use `NTPTime` on Windows

If HADB detects a clock adjustment of more than one second, it logs it to the node history file, for example:

    NSUP INF 2003-08-26 17:46:47.975 Clock adjusted.
     Leap is +195.075046 seconds.

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