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The concept of virtualization as a solution for scaling cloud applications by adding server instances at the edge. It covers the importance of keeping response times within reasonable bounds and the role of virtualization tools like server virtualization. The document also explains the concept of virtualization and its various types, with a focus on machine virtualization.
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Can "scale" cloud applications "on the edge" by adding server instances. (So far, haven't considered scaling the interior of the cloud). Recall: where we are clients App servers form an outer edge Distributed services form an inner core (JDO) Recall: where we are Docsity.com
how demand changes over time how quickly you can re-allocate server power to the edge nodes. key tool: virtualization. The safe operating bounds of the edge nodes of the cloud are based upon: Flowless switching between edge nodes. Response time P = tserver + tnetwork + tcloud. tnetwork is just client-to-edge and edge-to client. tcloud includes networking inside the cloud. Both of these are subject to their own SLAs. So we concentrate on keeping tserver within reasonable bounds. Assumptions for today's discussion Point for today Docsity.com
In its simplest form, creating a fictional version of a thing that acts like the real thing. This is called "virtualizing a thing". Many possible things... What is virtualization? What is virtualization? Docsity.com
Machine virtualization : thinking of a physical machine as "hosting" one or more virtual machines. I/O virtualization : sharing an I/O device with several running operating systems, perhaps even on different physical machines. Filesystem virtualization : making one instance of an operating system behave as if it were multiple, distinct instances by controlling filesystem access. Program virtualization: program is compiled to run on a virtual machine, e.g., the Java Virtual Machine (JVM). Several kinds of virtualization: A very broad term Docsity.com
Repurposing a server can require rebuilding the whole operating system. This can take (relatively) a lot of time. Virtualizing the machine allows two or more operating systems to share it. (One can be running normally even while another is being built.) Also, whole operating system instances can be prebuilt and latent, ready to start running when needed. Why we need machine virtualization Why we need machine virtualization Docsity.com
Separate sections of memory. Separate disk. Running two operating systems is like running two "programs". Most things about machine virtualization are easy. A disk drive doesn't take well to being asked to read something during a write. An I/O driver is a piece of software designed to maintain proper device state. Devices have state. Hard part: sharing resources and devices. Therefore, most of the work of machine virtualization is I/O virtualization. Machine and I/O virtualization Docsity.com
Best thought of as a miniature operating system for the machine Runs instances of operating systems as if they were application programs! is (theoretically!) unaware of the other instances. has its own memory and disk. Is scheduled to use the CPU(s) by the hypervisor. Each instance The hypervisor The hypervisor Docsity.com
