The diploma thesis is focused on expansion of current KVM virtualization infrastructure with network storage in a web hosting company environment. The first part describes the basics of the network storage field, and the virtualization field as well. This is amended by a description of the current solution in the company, which is going to be expanded. The searching for suitable innovative solution is following, several variants are found, each of them is commented and their advantages and disadvantages are summarized. The realization of the selected solution is implemented, including the testing on the practical part.

Fault tolerance is essential in a production-grade service delivery network. One of the solution is build a clustered environment to keep system failure to a minimum. This thesis examines the use of high availability and load balancing services using open source tools in GNU/Linux. The thesis discusses some general technologies of high availability computing as virtualization, synchronization and mirroring. To build relatively cheap high availability clusters is suitable DRDB tool. DRDB is tool for build synchronized Linux block devices. This paper also examines Linux-HA project, Redhat Cluster Suite, LVS, etc. Content Delivery Networks (CDN) replicate content over several mirrored web servers strategically placed at various locations in order to deal with the flash crowds. A CDN has some combination a request-routing and replication mechanism. Thus CDNs offer fast and reliable applications and services by distributing content to cache servers located close to end-users. This work examines open-source CDNs Globule and CoralCDN and test performance of this CDNs in global deployment.

Virtualization is a technique that allows several virtual machines (VMs) to run on a single physical machine (PM) by adding a virtualization layer above the physical host's hardware. Many virtualization products allow a VM be migrated from one PM to other PM without interrupting the services running on the VM. This is called live migration and offers many potential advantages like server consolidation, reduced energy consumption, disaster recovery, reliability, and efficient workflows such as "Follow-the-Sun''. At present, the advantages of VM live migration are limited to Local Area Networks (LANs) as migrations over Wide Area Networks (WAN) offer lower performance due to IP address changes in the migrating VMs and also due to large network latency. For scenarios which require migrations, shared storage solutions like iSCSI (block storage) and NFS (file storage) are used to store the VM's disk to avoid the high latencies associated with disk state migration when private storage is used. When using iSCSI or NFS, all the disk I/O operations generated by the VM are encapsulated and carried to the shared storage over the IP network. The underlying latency in WAN will effect the performance of application requesting the disk I/O from the VM. In this thesis our objective was to determine the performance of shared and private storage when VMs are live migrated in networks with high latency, with WANs as the typical case. To achieve this objective, we used Iometer, a disk benchmarking tool, to investigate the I/O performance of iSCSI and NFS when used as shared storage for live migrating Xen VMs over emulated WANs. In addition, we have configured the Distributed Replicated Block Device (DRBD) system to provide private storage for our VMs through incremental disk replication. Then, we have studied the I/O performance of the private storage solution in the context of live disk migration and compared it to the performance of shared storage based on iSCSI and NFS. The results from our testbed indicate that the DRBD-based solution should be preferred over the considered shared storage solutions because DRBD consumed less network bandwidth and has a lower maximum I/O response time.