I was interested in having our VM system keep time more accurately without the use of a sysplex timer, so I wrote a series of programs to set VM's time at IPL using SNTP.
I'm a little disappointed with the results, since I can only get to about 1 second accuracy, I was hoping for sub-second (currently our time server is +1.0545 from our VM time). At least I have been able to cut the operator out of the time setting loop, and avoid some of the horrors they created. During testing on second-level, I found that VM would accept a dynamic time change and keep running, even with a ridiculous change (like to the 1940s). However I should note that dynamically setting the time is completely unsupported by IBM, and I was warned of potential dire consequences of doing so in production. This is why I set the time at IPL, then do an immediate SHUTDOWN REIPL before running with the new time and just monitoring the time after that. Since we IPL once a month, this works for us. If you are interested in the programs, drop me a note offline, and I can send the bunch to you. The programs assume that you are running VM on GMT (UCT, ZULU). > -----Original Message----- > From: Steven A. Adams [SMTP:[EMAIL PROTECTED] > Sent: Friday, May 30, 2003 5:40 PM > To: [EMAIL PROTECTED] > Subject: Time Sync > > This might be a little off topic so feel free to let me know if it is. > > Our z/800 is about 90 seconds off of time with the rest of the network > and this is starting to cause some havoc with an application that we are > currently developing. I have been told that getting the mainframe to > sync up is probably an expensive proposition. I am being told that there > is not a way to use ntpd under one of my Linux guests to set the clock > and propagate these settings through VM to the CTC. So, if you don't > mind me asking, what solutions are commonly used for time sync? > > Thanks in advance, > > Steve > --
