using ntp on oracle db server

[B.O. CHOI]

Is there any problems when using NTP on oracle db server.
such as ...

1. when ntp server was not reachable a few days.
2. and db server's time is become slew or faster then real time.
3. and then, now the ntp server become reachable
4. the db server's time will try to chase the real time of ntp server. and will change it's time.

if so.
is there any problems related to oracle database.

[Roger Baptiste]

<<. when ntp server was not reachable a few days. >>

No, i use ntp on database servers and no problem.

But, depends on what your problem is. If the
NTP server is not reachable, than it won't be
having a source to keep time with. Still it should not make that much of a differnce, if it is not for too long. Also, why don't you use secondary NTP servers? NTP servers are supposed to be UP all the time!! How can you have a unreliable NTP server?

<4. the db server's time will try to chase the real time of ntp server. and will change it's time.>

Yes, it tries to catch up with the reference time in a short burst. Again, it should not be more than a few seconds, if the server is down for a short while.

In short there is no problem with using NTP pn DB server. I would suggest to add a secondary NTP server in your setup.

HTH
raj

[Sridhar Bhaskarla]

Once the time is sync'ed up there is a very little chance that the system will go out of sync. As long as the system is up and running, the time will not be slowed down or become fast. And it is not advisable to keep a single time server. So as suggested by Rajman, you need to configure a secondary time server.

-Sri

[A. Clay Stephenson]

Hi:

You should use NTP in a database environment; however, you want to force slewing behavior with the -x argument to xntpd. The thing that you want to avoid is step adjustments. With slewing behavior in essense the rate of the clock 'ticks' slows down or speeds up until the time is synced rather than a series of rather abrupt changes. With a secondary time server, you should have no problems and all the servers on your network should be able to acheive accuracy to within a few milliseconds.

[B.O. CHOI]

Thanks Mr. Rajman, Sridhar and Clay ...

I thought the situation of occring accident on connection
between our local network and internet.
if so, any secondary ntp server on outer network may useless.
I am afraid of that kind of situation.

and one more question ...

Is it possible for One host can be a ntp client of ntp server
on outer network.
and simultaneouly Be a ntp server of other local hosts.

if possible please let me know how to configure.

thanks

[Steven Sim Kok Leong]

Hi,

The short answer is yes.

Below is extracted from:

http://docs.hp.com/hpux/onlinedocs/B2355-90685/B2355-90685.html

Configuring Your Primary NTP Server
============================================
Step 1. Install the latest version of NTP.

Step 2. Select a source of time: radio receivers, public time server, local NTP machine.

Step 3. Add the name of the server to the file /etc/ntp.conf:

server my_server.my_domain.my_org.com

Note that my_server.my_domain.my_org.com is the complete name of your server.

Step 4. Specify the time source and add its information to the configuration file.
For Radio Receivers:
Uncomment the following "fudge" line found at the end of the file /etc/ntp.confserver 127.127.26.1. #fudge 127.127.26.1 time1 -0.955

Make a link to the device file that corresponds to the serial port you are connecting to the GPS unit by typing the following: /usr/bin/ln -s /dev/tty0p0 /dev/hpgps1

(device name for HP GPS)

For the Local NTP Machine, add the following line to the end of the /etc/ntp.conf file:

server 127.127.1.1

fudge 127.127.1.1 stratum 10

Make a link to the device file that corresponds to the serial port you are connecting to the GPS unit by typing the following: /usr/bin/ln -s /dev/tty0p0 /dev/hpgps1

Only use this option if NTP will be used in an isolated environment with no radio clock, NIST modem or Internet connection available. You can also use this if a particular server clock will be used as a last resort, when all other normal synchronization sources have gone away.

Step 5. Start the NTP daemon.
Edit the /etc/rc.config.d/netdaemons file. Set the variable NTPDATE_SERVER equal to an NTP time server that is reachable. For example:

NTPDATE_SERVER=15.13.108.1

This will run the /usr/sbin/ntpdate command just before the NTP daemon is started, and bring your system clock very close to the other server to start.

Set the XNTPD variable to 1.

This will cause the daemon to be started automatically when your system makes the transition from run level 1 to 2.

Start the daemon using the startup script:

/sbin/init.d/xntpd start

Verify the daemon process is running. Type:

ps -ef | grep ntp

The line /usr/sbin/xntpd should appear in the list of running processes.
============================================
Hope this helps. Regards.

Steven Sim Kok Leong
Brainbench MVP for Unix Admin
http://www.brainbench.com