Thomas Kern wrote, re guest migration: >I thought the early prototype of this was the Single-System-Image code >written at University of Waterloo back in the early 1980's.
Now why would you think that? Just because Romney wrote both of them... ;-) The SSI SWITCH command was a lot of fun. It moved a VM from one machine in an SSI cluster (only they weren't called "clusters" back then) to another; we would do this so we could reIPL one of the boxes, or for load-balancing. The problems were somewhat different from today: CP was less well-structured; bandwidth between machines was lower; but guests were even smaller than the bandwidth difference, so it was practical to simply suspend the guest, move it, and resume. That's less advisable with an 8GB guest, even over a fast OSA, so the current prototype does some interesting stuff to move memory, then go back and re-move (not "remove!) pages that changed during the first move. It does this several times until it either gets a "clean" pass or throws up its hands, "stuns" the guest, and moves the remaining pages. So you can move an only moderately active, very large guest without noticeable disruption. Moving between CECs is an interesting concept; I'd imagine that getting the functionality out there within a CEC would be the first priority for obvious reasons, and then the inter-CEC problem could be examined. A reasonable implementation would require a VLAN across the CECs for network transparency. For extra credit, while the guest is being containerized, it might be nice to be able to store a copy of the state, a la the old VMSAVE facility. I'm not sure how useful this actually is, since any changes to data on DASD wouldn't be reflected in the state, so the saved image might not be usable. But it's fun to think about... ...phsiii ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
