Enterprise systems often use replication technology to keep multiple instances of applications or data stores in synchronization. Existing data replication techniques are primarily storage based and are usually applied at coarse time granularity. Furthermore, they can not be used to achieve service replication that requires state synchronization in addition to disk synchronization.
Continue reading »As more and more data centers embrace end host virtualization and virtual machine (VM) mobility becomes commonplace, we explore its implications on data center networks. Live VM migrations are considered expensive operations because of the additional network traffic they generate, which can impact the network performance of other applications in the network, and because of the downtime that applications running on a migrating VM may experience. Most virtualization vendors currently recommend a separate network for VM mobility. However, setting up an alternate network just for VM migrations can be extremely costly and thus presents a barrier to seamless VM mobility. Therefore, it is apparent that VM migrations should be orchestrated in a network-aware manner with appropriate QoS controls such that they do not degrade network performance of other flows in the network while still being allocated the bandwidth they require for successful completion within the specified time lines.
Continue reading »Steady state VM management in data centers should be network-aware so that VM migrations do not degrade network performance of other flows in the network, and if required, a VM migration can be intelligently orchestrated to decongest a network hotspot. Recent research in network-aware management of VMs has focused mainly on an optimal network-aware initial placement of VMs and has largely ignored steady state management.
Continue reading »Human error has been identified one of the major factors behind system outages and network downtime in a number of previous research papers and surveys. Gartner statistics show that almost 40% of unplanned application downtime is caused due to operator errors such as unintentional changes to network configuration resulting in a network outage, patch installations, service restart, etc. Yet, system admin activities on production IT systems are rarely properly logged and monitored. Existing tools to track user activities either produce too much information without any hints of a potential outage scenario or too little information to be useful in a meaningful way.
Continue reading »Most enterprises today run their applications on virtual machines (VMs). VM mobility - both live and offline, can provide enormous flexibility and also bring down OPEX (Operational Expenditure) costs. However, both live and offline migration of VMs is still limited to within a local network because of the complexities associated with cross subnet live and offline migration. These complexities mainly arise from the hierarchical addressing used by various layer 3 routing protocols. For cross data center VM mobility, virtualization vendors require that the network configuration of the new data center where a VM migrates must be similar to that of the old data center. This severely restricts wide spread use of VM migration across data center networks. For offline migration, the above limitations can be overcome by reconfiguring IP addresses for the migrated VMs. However, even this effort is non-trivial and time consuming as these IP addresses are embedded in various configuration files inside these VMs. As enterprises grow and new data centers emerge in different geographic locations, there is a need to interconnect these data centers in a way that allows seamless VM mobility.
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