This page includes technical information about different aspects of the virtualization service:
Hardware
The Server Virtualization Service utilizes Cisco UCS blade servers, built on the industry-standard Intel architecture, and UCS Fabric Interconnects ("FIs"). Each physical blade server ("host") has two (2) multi-core Xeon processors providing at least 24 cores per host, and has at least 256 GB of RAM on each host. The hosts have redundant power, cooling, and network and storage connections. With assistance from the virtualization software, the hardware is clustered in an N+1 configuration -- there are enough compute resources to tolerate at least 1 host failure and still support the workload of the virtual servers ("VMs" or "guests").
The FIs provide management services, and network and storage connectivity for each group of blade servers. They also have redundant power and cooling, and operate as a failover pair. They use multiple 10 Gigabit Ethernet and 8 Gigabit Fibre Channel uplinks to connect the blades to the datacenter IP and storage networks.
With the Cisco UCS architecture and the redundant power, network and storage capabilities provided by the datacenter facilities housing the servers, the Server Virtualization Service is a highly available and scalable service. The hosts are also monitored 24x7 by our management systems and will notify staff if there are any errors.
Software
The Server Virtualization Service uses a "hypervisor", virtualization software running directly on each host. This software uses a combination of direct execution, hardware-assist and emulation to run multiple, independent virtual server instances that are abstracted away from the underlying physical hardware. These virtual servers can run many Intel x86-compatible operating systems (though some guest OSes may run but are not supported). It also provides additional capabilities, such as software-based power control, virtual hardware configuration and console and features such as VM "snapshots".
The ITS-Managed and Co-Managed Virtualization offerings are available on both the VMware vSphere platform (the ESXi hypervisor) and the Microsoft Hyper-V platform. The ITS-Secure and Co-Location offerings are currently provided only by vSphere. Both hypervisor platforms provide central management tools (vSphere vCenter, MS SCVMM) to configure and maintain the environments and to support additional layered functionality.
Services are deployed on clusters of hosts to provide N+1 (or better) redundancy within the cluster, and hosts can be added to a cluster to provide additional compute resources. The hypervisors provide the ability to migrate (vMotion or Live Migrate) a VM between hosts without shutting down the VM, which allows for non-disruptive maintenance of the hosts. This capability is also leveraged to perform automated balancing of VM workloads across the cluster to ensure all VMs have the resources they need. In the event of a host crash (hardware or software fault), all of the guests that were running on that host will automatically restart on one of the other hosts in the cluster, typically within a few minutes, minimizing the downtime due to catastrophic host failure.
Storage
Virtual Server storage is provided by both IP-based Network Attached Storage (NAS) storage systems and Fibre Channel-based block storage systems. These enterprise-class platforms provide highly available storage for VMs, and, in many cases, high-performance all-flash storage. In some cases, the storage provides additional capabilities such as growing the storage volume, volume-level snapshots, and replication to another system in another datacenter. The specific storage available depends on the Virtualization offering. In addition, other storage may be attached within the guest itself (e.g. Files@Iowa departmental or application shares).
The hypervisor additionally allows for resizing VM disks and live migration of VMs from one storage volume to another. Certain VM and storage configurations also allow for shared storage access, providing the ability to build a virtual SQL Server cluster.
VM backup services vary depending on the Virtualization offering.
Client Benefits
For the Co-Location offering, and in some additional cases, customers are provided access to VM management capabilities. These capabilities include virtual console access, power control (power on/off, restart/reset), and remote media connection (ISO or local media), as well as access to performance data and task/event history for the VM.
VM snapshots (with or without current memory state), and the rollback or deletion of snapshots, can be done on request to the ITS Server Support Team. Direct ability to perform snapshot operations is not offered at this time.