I would not run linux virtual machines under a 2nd level z/VM for production - including VAL/DEV which, to me, is production, albeit lower case. 3rd level linux is not an ideal production environment. I think IBM would say this is not a production environment. LPARs LPARs LPARs. You can achieve your desired separation of say PROD, VAL, and DEV by putting them onto their own vswitches using different OSA ports, or even over the same OSA ports using vlan while remaining in 1 LPAR. Either way you get complete isolation. I support a few production environments where we have over 35 vswitches coming into the same LPAR to achieve isolation. Running 2nd level z/VM systems is invaluable for testing, servicing, patching, but not as a host for linuxen providing any services. On the issue of LPARs, there is a cost to separating out workloads into multiple LPARs as desirable as this may be. The memory assigned to an LPAR is committed; so if you have a lightly used LPAR its memory is unusable by other LPARs. Splitting workloads out on different LPARs can be useful for HA purposes. If you have some sort of broker or workload balancer running on your physical servers, you can take an LPAR down for maintenance, and still provide application availability on a different LPAR. Highly attractive. David Kreuter
________________________________ From: The IBM z/VM Operating System on behalf of Martin, Terry R. (CMS/CTR) (CTR) Sent: Thu 12/4/2008 8:57 PM To: IBMVM@LISTSERV.UARK.EDU Subject: [IBMVM] Configuartion question Hi We are moving toward taking our POC into production. This workload is moving from Solaris running UNIX. The environment is 3 zone architecture. Our client's business requirements calls for this 3 zone environment to remain separated. It requires UAL5 security level. To this end we have six LPARS each sharing 7 IFLS with plenty of real memory on each. One of the six LPARS is our test LPAR that will have multiple levels of VM for testing and such. My question: some of our folks believe that this is an excessive number of LPARS and that it defeats the purpose of VM. Now I understand how VM works and its' ability to virtualize reducing the need for large LPAR configurations. I know that we could, lets' say combine our PROD and VAL/DEV environments that are currently running in separate LPARS into one LPAR and run a second LEVEL VM for the VAL/DEV. My contention is that if it is what is needed to fit the business requirements of the client then having six LPARS is not catastrophic. We have plans for another 16 z/Linux guests to run in the existing configuration in the next few months not requiring additional LPARS. I am not an LPAR bigot. Can anyone comment in general on the pros and cons of running LPARS as opposed to running the multiple environments under one LPAR and getting separation logically by having multi levels of VM rather then physical separation by having the environments running under a single level of VM? In the end it probably will not matter if the client insists that we need to proceed as we are. Just trying to get a prospective of those who are more experienced then myself!! Thanks, Terry
