What an interesting question. PC clocks are of such abysmal quality that they are not remotely usable for even the most simple business mission. Of course there is a need to be able to constantly correct them from a reliable time source. And I do mean constantly. Every few seconds. I recall some servers not too long ago that stopped the clock to do an ordinary disk I/O.
Compare to most any industrial equipment (to include the MF) that uses time. They almost always have a high quality clock that is accurate to milliseconds per fortnight without any outside help. The MF is especially reliant on a time base because it offers an ironclad 100% guarantee of data integrity and recoverability. (Of course, you have to do your part to exploit the guarantee.) To me, it makes perfect sense that the MF could not rely on any time source that does not meet its sub nanosecond needs. It also follows that thinking that servers that have to have an external time source are superior in any way to those that don't is just plain, ah, um, naïve. The only reason you need an external time source for a MF is when you want to have the exact same time setting (to a few nanofortnights) as another MF. Fortnight? I really used that metric? Must be showing my age ;-) http://en.wikipedia.org/wiki/Fortnight My $0.02, and forgive me for having a little fun on a Friday evening. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of McKown, John Sent: Thursday, May 11, 2006 1:39 PM To: [email protected] Subject: TOD clock discussion. I vaguely understand why the hardware, TOD, clock is inviolate. That is, why a person cannot simply change it to a new value. However, unfortunately, this is becoming yet another "the mainframe is junk" argument. The UNIX and Windows servers are constantly adjusting their clocks using an SNTP server. The mainframe clock, set who knows when, is about 3 minutes "slow". I guess my question is: Why does IBM and other software vendor depend on the TOD clock not changing "drastically" and never, ever, "going backwards"? How would you address this "complaint". Without spending any money (gilt, lucre, dinero, ...) -- John McKown Senior Systems Programmer HealthMarkets Keeping the Promise of Affordable Coverage Administrative Services Group Information Technology This message (including any attachments) contains confidential information intended for a specific individual and purpose, and its content is protected by law. If you are not the intended recipient, you should delete this message and are hereby notified that any disclosure, copying, or distribution of this transmission, or taking any action based on it, is strictly prohibited. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html NOTICE: This electronic mail message and any files transmitted with it are intended exclusively for the individual or entity to which it is addressed. The message, together with any attachment, may contain confidential and/or privileged information. Any unauthorized review, use, printing, saving, copying, disclosure or distribution is strictly prohibited. If you have received this message in error, please immediately advise the sender by reply email and delete all copies. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
