Thanks John. We use an external timer. I just wondered if after they replace the cables do I have to do anything like a POR (power on reset) for the lpar to get it's time refreshed from the external timer. I will check the doc you mention here. You say zVM doesn't keep in synch but I wonder if the lpar does.
-----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Romanowski, John (OFT) Sent: Thursday, May 08, 2008 12:40 PM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: How does z/VM obtain time ? Ann, If you don't use the z/VM IPL prompt to change it's LPAR'as TOD clock then z/VM's LPAR gets its TOD clock set equal to the External Time Reference (ETR) or on z10 Server Time Protocol (STP) time at LPAR-activation time if you're using an ETR or STP, and thereafter the LPAR's TOD drifts a bit. Unlike z/OS, z/VM doesn't include the code that supports keeping in synch with the ETR/STP. See Sysplex Timer and VM http://www.vm.ibm.com/faq/vmgen.html#Header_2 See http://www.redbooks.ibm.com/redbooks/pdfs/sg242070.pdf page 83 section 4.2 VM/ESA Long story short- if your machine's TOD clock is set ok then just let z/VM's LPAR inherit it. -------------------------------------------------------- This e-mail, including any attachments, may be confidential, privileged or otherwise legally protected. It is intended only for the addressee. If you received this e-mail in error or from someone who was not authorized to send it to you, do not disseminate, copy or otherwise use this e-mail or its attachments. Please notify the sender immediately by reply e-mail and delete the e-mail from your system. ________________________________________ From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Smith, Ann (ISD, IT) Sent: Thursday, May 08, 2008 11:48 AM To: IBMVM@LISTSERV.UARK.EDU Subject: How does z/VM obtain time ? I am not sure what the options are for external timers and I think the z9's and probably z10's have some new way of obtaining time. We currently have external timers that are somehow magically connected to the zVM lpars. The timers obtain time from a naval observatory. Anyway, electricians managed to kill some of the mainframe cables (copper melts). They are replacing the cables to the timers this weekend. I am wondering how to verify the new cables work. I always thought (I could be wrong) zVM obtained the time from the hardware (HMC? SE?). Ann Smith Mainframe Systems Support -zVM and zLinux Support Integrated Technology Delivery IBM Global Service Integrated Operations At The Hartford Work phone: 860-547-6110 Pager: 800-204-6367 Email: mailto:[EMAIL PROTECTED] ************************************************************************ * This communication, including attachments, is for the exclusive use of addressee and may contain proprietary, confidential and/or privileged information. If you are not the intended recipient, any use, copying, disclosure, dissemination or distribution is strictly prohibited. If you are not the intended recipient, please notify the sender immediately by return e-mail, delete this communication and destroy all copies. ************************************************************************ * ************************************************************************* This communication, including attachments, is for the exclusive use of addressee and may contain proprietary, confidential and/or privileged information. If you are not the intended recipient, any use, copying, disclosure, dissemination or distribution is strictly prohibited. If you are not the intended recipient, please notify the sender immediately by return e-mail, delete this communication and destroy all copies. *************************************************************************
