Re: Synchronize Time Between Mainframe and Servers?
- From: timothy.sipples@xxxxxxxxxxxx (Timothy Sipples)
- Date: 24 May 2007 00:07:28 -0700
Yes, we're all converging on the correct answers. Here's a quick summary.
There are two supported paths for IBM mainframes to synchronize with an
external clock source, and then a few different types of external clocks
that can be used. The older option is to install a Sysplex Timer
(9037-002) and then connect the Sysplex Timer to an external time reference
(ETR) via the 9037 serial port. You can use a dial-up modem (to the U.S.
NIST modem pool, for example), a shortwave radio receiver (to NIST's WWV
for example), or a GPS receiver. GPS receivers are certainly more in vogue
now, and there are several companies building such boxes. Configure
everything correctly (including operating systems) and you're all set.
Note that some people have figured out how to use that serial port
connection with other devices that could deliver the time information
bytes. Not recommended.
Support for the 9037-002 will end at some point in the future, so nowadays
IBM is recommending STP (Server Time Protocol) which is supported on z890,
z990, z9 BC, and z9 EC systems. At present your external time reference
would be via dial-up modem to NIST and similar time source modem pools --
that's supported much like the Call Home feature and easy to set up on the
HMC. IBM has a Statement of Direction expressing the company's intention
to support two more external time sources in the future: GPS and any
arbitrary NTP server (NTPD). My hunch is the latter option will come with
all sorts of warning statements -- fall victim to time of day spoofing and
you could have horrible problems -- but let's leave that aside for now. :-)
At present you have two choices for keeping mainframe time in sync with
other servers' time clocks:
1. Make the mainframe boss. This is the best choice for a lot of reasons.
Set up the mainframe to get its external time reference, then use the
built-in time server so that other servers can get time sync over the
network, perhaps in a hierarchy.
2. Have both the mainframe and your organization's master time server (if
they are unfortunately different entitites) both sync to the same external
time reference (such as NIST dial-up). This might not offer as much
accuracy, but it might be sufficient for certain purposes.
- - - - -
Timothy Sipples
IBM Consulting Enterprise Software Architect
Specializing in Software Architectures Related to System z
Based in Tokyo, Serving IBM Japan and IBM Asia-Pacific
E-Mail: timothy.sipples@xxxxxxxxxx
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