Changes between Version 62 and Version 63 of WikiStart


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Timestamp:
10/13/11 15:04:05 (13 years ago)
Author:
lvpeng
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  • WikiStart

    v62 v63  
    11= Welcome to [wiki:WikiStart Resilire] Project =
    22
    3 High availability refers to a system and associated service implementation that is continuously operational for a long period of time. Whole-system replication is a conventional way to increase system availability ---- once a primary machine fails ---- the running applications are migrated and resumed on backup machine(s). However, there are several limitations that make this method unattractive for deployment: it needs specialized hardware and software, which are usually expensive. Additionally, such a system may also require complex customized configurations, which are difficult to manage and maintain.
     3High availability refers to a system and associated service implementation that is continuously operational for a long period of time. Whole-system replication is a conventional way to increase system availability ----
     4once a primary machine fails, the running applications are migrated and resumed on backup machine(s).
     5----
     6However, there are several limitations that make this method unattractive for deployment: it needs specialized hardware and software, which are usually expensive. Additionally, such a system may also require complex customized configurations, which are difficult to manage and maintain.
    47
    58These limitations are efficiently overcome by virtualization: all applications now run on a virtual machine (VM). Thus, whole-system replication can easily and efficiently be implemented -- a copy of the whole VM is continuously checkpointed and saved on a backup machine. As VMs are totally hardware-independent, the cost is much lower compared to the hardware expenses in traditional high availability solutions. Besides, virtualization technology can facilitate the management of multiple VMs on a single physical machine. With virtual machine monitors (VMM), the service applications are separated from physical machines, providing increased flexibility and improved performance.