Legolas Wood writes: >As There are several OSs that run on System Z, Which one is >the Default OS on IBM mainframe? I mean, Does IBM sell all >of them to a customer when it buys a mainframe or customer >has the option to select the OS ?
It's entirely the mainframe owner's choice. A single mainframe can run all 5 at the same time if the owner wishes. >Another question is, Z/VM allows us to install several >"Linux for System Z" on it and for example cluster the >application server which is installed on it. so we can >achieve high availability and handle heavy work load, >what about Z/OS ? It has not a virtual machine, so it >can run one OS at the same time. First of all, just as with Linux, z/OS can also run within z/VM virtual machines. Actually, all 5 operating systems can, including z/VM itself. But bear in mind that each mainframe has first level virtualization called LPARs (logical partitions), managed by something called PR/SM. This is all part of the hardware itself and comes with every system. You can define up to 30 (System z9 BC) or up to 60 (System z9 EC) LPARs without z/VM, and PR/SM can dynamically allocate resources to each LPAR. This is how most mainframe owners run z/OS, in LPARs. So why is it more common to run z/OS in LPARs and Linux in z/VM (with z/VM in the LPAR)? Because z/OS itself has considerable virtualization capabilities. I would recommend studying the z/OS references mentioned earlier to start to get an idea about the many characteristics that make z/OS unique, including z/OS address spaces, WLM, RRS, ARM, UNIX System Services, DVIPA, Parallel Sysplex, GDPS, and much more. >My question is, When we have websphere and DB2 as >main components of a big system, which OS can be selected >for them? WebSphere Application Server is available on the mainframe twice: both for z/OS and for Linux on z. There are versions of DB2 available for z/OS, Linux on z, z/VSE, and z/VM (4 out of the 5 supported operating systems). >I thought that Z/VM could be the choice as it simulate the >way that we already deploy application server instances and >database, but If Z/VM is correct choice, what is use of Z/OS? There is a long list of capabilities z/OS has that Linux does not. For example, z/OS runs CICS and IMS, the world's two most popular transaction processing systems. (The other half of IMS is a very popular and important information management system.) But, in simple terms, here's the comparison: while Linux on System z offers the highest qualities of service of any Linux implementation, z/OS offers the highest qualities of service of any operating system. Qualities of service include characteristics like reliability, availability, security, disaster recovery, performance and scalability, manageability, etc. You can run both of course, and they complement each other very well. - - - - - Timothy Sipples IBM Consulting Enterprise Software Architect Specializing in Software Architectures Related to System z Based in Tokyo, Serving IBM Japan and IBM Asia-Pacific E-Mail: [EMAIL PROTECTED] ---------------------------------------------------------------------- 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
