When we arrive at the hot site, there is a VM system IPL'ed with a z/OS starter
system ready for us. We do an initial load of 8 tapes to get our
recovery environment built, then we IPL our z/OS recovery system, as a VM guest
on the main z/VM system running on the vendor z/900 in basic mode. We
then use our recovery system to recover DFDSS imaged disk volumes for z/VM and
z/Linux.
Once OUR z/VM and z/Linux volumes are restored, we IPL our z/VM system as a
guest on the Vendors top Level VM under which the Vendor built starter
system and our z/OS recovery system is running.
We then start Linux guests on OUR VM system running as a guest on the vendor
z/VM. We have 6 gigs of memory allocated to the guest running our VM as
well as 2 dedicated CP's.
As to why we do it? That's the environment we were presented when we undertook
contracting with this vendor. The state of Minnesota also recovers with
this vendor but THEY don't do VM under VM shenanigans or anything like that.
As to why we STILL do our VM and Linux this way after 4-5 tests indicating that
the performance absolutely SUCKS is a mystery I will not even consider
trying to answer as it's out of my hands. the powers that be here are directly
ignoring the recommendations of 3 Sr. Systems Software Programmers that
we try it as a first level guest in parallel with running one of our Linuxes
under our VM again on their VM in favor of the opinion of one person who
1) doesn't work with WebSphere and 2) doesn't work with Linux. They don't even
want to hear anything else except pursue it from where the symptoms are
showing up.
Has me frustrated to the point of resume' polishing.
-J
P.S. - To the list - Thank you for putting up with my somewhat vitriolic pleas
for help/understanding on this.
Bennie Hicks <[EMAIL PROTECTED]>
Sent by: Linux on 390 Port
<[email protected]>
To
[email protected]
cc
05/05/2006 10:52 AM
Subject
Re: What
configurations are people using for Disaster Recovery for Linux under
Please respond to z/VM
Linux on 390 Port <[email protected]>
Just curious, since you are talking DR and I assume hotsite. Are you
IPL'ing your VM system on that hardware directly, or running it second
level under the hotsite floor system (don't know why you would do that
just speculating...)???
Alan Altmark wrote:
>On Thursday, 05/04/2006 at 02:19 EST, James Melin
><[EMAIL PROTECTED]> wrote:
>
>
>>I just want to reconcile what the People here are saying with what the
>>
>>
>folk on
>
>
>>the list say regarding what constitutes a 3rd level guest....
>>
>>I'm being told by our head sysprog AND someone else with considerably
>>
>>
>more VM
>
>
>>experience (he's the new guy) that in Basic mode, the DR VM system is
>>first Level, our VM is second level and therefore any guests running
>>
>>
>under OUR
>
>
>>VM are second level.
>>
>>It sounds to me like people here on the are saying that the DR VM system
>>
>>
>is
>
>
>>first level, OUR VM system is second level, and the Linux Guests running
>>under our VM under the DR vendor VM are in fact executing third level,
>>
>>
>and
>
>
>>hitting the SIE not in hardware problem.
>>
>>Which is correct?
>>
>>
>
>LOL. It just depends on training and local custom. Some people use the
>"level" to describe levels of virtualization. There is "1st-level SIE"
>(SIE1) and "2nd-level SIE" (SIE2), so some say that any operating system
>which runs under the ausipices of SIE2 is a "2nd-level guest". But I
>would say the majority would use "3rd level" to describe the guests of a
>2nd level z/VM system.
>
>In Basic mode, 1st level CP (CP1) uses SIE1 to dispatch the the 2nd level
>CP (CP2), which uses SIE2 to run your 3rd-level guest (Guest3). Everything
>is wonderful.
>
>In LPAR mode, LPAR uses SIE1 to dispatch CP1, which uses SIE2 to dispatch
>CP2, leaving leaves none for Guest3. This means that when CP2 issues the
>SIE instruction, it will cause a SIE2 break on CP1. That, in turn, causes
>CP1 to construct a SIE descriptor, converting CP2's view of Guest3 to that
>viewed by CP1, or to simulate whatever needs to be simulated. This
>process is called "Virtual SIE" (VSIE).
>
>The itty bitty time slices and possibly small amount of resident guest
>memory in CP1 real memory means that VSIE doesn't perform very well.
>
>Are we having fun yet?
>
>Alan Altmark
>z/VM Development
>IBM Endicott
>
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