> To have Linux Sync with the TOD of VM is there a setting in the Linux > environment or is this done automagically or do we use NTP > and given VM as > a server?
You get the correct time from VM at Linux IPL. If you want constant correction, you need NTP in the Linuxen, pointed at either the VM SNTP implementation that Dave J mentioned or another NTP host somewhere else in your network. NTP does have an impact on virtual machine farm performance in that it does wake up the virtual machine with legitimate work to do at regular intervals. Most mainframes have very stable clocks, so the drift is relatively minimal -- as someone else mentioned, you may be able to get away with just running ntpdate every night at midnight rather than needing to run xntpd all the time. If you are planning to use Kerberos or other security protocols that use a time nonce in their authorization validity checking, you may not have a choice but to run NTP all the time. With those protocols, everyone inside *and* outside the box has to agree on the time within a very small delta, and even the minimal drift of the mainframe clock may be unacceptable (depending on how obnoxious your security people feel like being).
