Personally, I would set up your VM system so that it is as device address independent as possible, so that you can pretty much restore and go on the DR system. We do this on our VM, and it works well. The devices that are problematic are the OSAs, and the remote communications controller (3745?), but these can easily be fiddled once our VM is up as the base system.
-----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of James Melin Sent: November 9, 2005 14:06 To: LINUX-390@VM.MARIST.EDU Subject: Re: Poor performance running VM under VM in a DR exercise I spoke to an IBM expert on things WebSphere on z/Series and he had this to say: _________________________________ You will experience much degraded performance when you are running Linux under VM under VM. My understanding of this is that it is caused by running the SIE (start interpretive execution) hardware instruction in software. VM uses the SIE instruction to run guest operating systems like Linux. When VM is itself running interpreted (2nd-level) then when it uses the SIE to run Linux that SIE is running in software emulation. So it's not just your WebSphere that is slow, but all of Linux, and any other guests running under the 2nd-level VM. You're probably not noticing the slowdown in Linux since Linux is quite "light" and doesn't really put much of a load on the system. But WebSphere will, and you'll notice the performance degradation. __________________________________ We are running VM under VM for the convenience of the DR Vendor. Rather than have to re-create our VM environment for us with different device addressing.... A couple questions : Any way to prevent third level guests from doing SIE in emulation? When we do our z/VM & z/Linux restores, the process we undertake is to do it from the 'starter system'. We restore to the real disk devices on the recovery system. The process of volume restore for Linux changes the Volser, so when our VM runs, the devices are at the address they've been told to be at in the VM directory and the labels have been changed to be what labels VM expects. The only real thing that needs to be resolved is recovery system device address definitions vs our 'native' device address definitions. Is it better to re-map our VM configuration to match the device addresses of the recovery hardware, or have the DR vendor create guests in the primary VM that match my Linux definitions? ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of or taking of any action in reliance upon, this information by persons or entities other than the intended recipient or delegate is strictly prohibited. If you received this in error, please contact the sender and delete the material from any computer. The integrity and security of this message cannot by guaranteed on the Internet. The Sender accepts no liability for the content of this e-mail, or for the consequences of any actions taken on basis of the information provided. The recipient should check this e-mail and any attachments for the presence of viruses. The sender accepts no liability for any damage caused by any virus transmitted by this e-mail. This disclaimer is the property of the TTC and must not be altered or circumvented in any manner. ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
