V=R - then why run under VM at all? As an old MVS production hand, I have to at least smirk at that ;) Why not VM for those things appropriate to VM and an LPAR or LPARs where appropriate, talking back and forth using hipersockets?
One of the configurations I see tried more and more often is a VM environment of a lot of small linux EC's to act as web servers and routers connected to one very large data base server (VLDB) (Linux LPAR, MVS LPAR or pSeries). Its these VLDB servers I'm talking about. These VLDB servers under Linux could use 2-10 GB of real memory and have hundred's of GB's or Terabytes of data at 15 ms access times or less. In these cases, why incur any VM? The apps themselves are large and the big buffer caches for Linux speeds up the I/O. This kind of app, is well suited for zSeries parallel escon/ficon channel architecture is and, if anything, I/O bound. Forcing the buffer space small only slows them down and using large memory under VM only adds unnecessary paging. Things like very large, frequently used table spaces and indices do much better in memory. Obviously, the issues of cost, performance, throughput, availability, and reliability, need to be stewed into the equation, but don't discount BIG penguins as an alternative. Regards, Jim Linux S/390-zSeries Support, SEEL, IBM Silicon Valley Labs t/l 543-4021, 408-463-4021, [EMAIL PROTECTED] *** Grace Happens ***
