VMWare have been specialising in server virtualisation since 2001. It has the largest market share especially in the enterprise market and therefore has a strong reputation for delivering virtualisation solutions. As it was the first company to make inroads in virtualisation it has over time built a large community and created partnerships with a wide range of technology companies. This is important as it ensures that there are a large number of hardware suppliers that ensure their products are compatible and also allows VMWare to make purpose built drivers for their hypervisor.
There are a number if versions of vSphere aimed at different requirements.
The vSphere Hypervisor is free and can be used on single servers to turn allow them to run virtual servers, this is the most basic version and does not allow centralized management through vCenter.
vSphere Essentials is the basic version aimed at smaller organisations. The Essentials license includes a single vCenter license and supports a maximum of 3 hosts with 2 CPU’s each with a maximum of 192GB RAM. Essentials Plus includes additional features as such as High Availability, Data Recovery and vMotion.
The vSphere Standard Accelerator Kit aimed at medium to large organisations also includes a single vCenter license. However the Standard kit allows up to 1000 hosts to be managed if the correct amount of licenses are purchased. The Standard license comes in increments of 8 CPUs & 256GB vRAM entitlement. Standard edition also includes additional features as such as High Availability, Data Recovery and vMotion.
The vSphere Enterprise Accelerator Kit and Plus versions are products that are aimed at large enterprise organisations. These include larger vRAM entitlements per vCPU 384GB and 576GB respectively allowing more VM’s to be created per host to increase VM density. There are also a variety of enterprise level features that are made available over the standard version such as Fault Tolerance, Hot Add, Storage vMotion and I/O Controls plus many more.
VMWare vSphere 5 uses the VMWare vSphere hypervisor which is essentially VMWare ESXi and is a purpose built bare-metal hypervisor. The two key factors are that it has a smaller foot print of just 144MB and an optimised direct driver model where hardware manufactures make drivers for the hypervisor.
The hypervisor is capable of hosting a large amount of VM’s per host. In addition it allows a maximum of 32 vCPU and 1TB per VM more than the competitors. However this requires the Enterprise Plus license, anything lower and you are limited to 8 vCPU per VM. The hypervisor allows serial port pass through and the ability to Hot Add vCPU/memory/disk and devices which are something that other vendors are not yet able to provide.
vSphere 5 has all the typical features that you expect from a virtualisation solution. These include centralised management, AD Integration, Live Migration, High Availability, Snapshotting, VM Templates, Dynamic Memory/CPU/Device assignment.
vSphere 5 has a number of innovative features that are not available from competitors just yet. These include:
• Storage vMotion - The ability to move the VMs vDisk on a running VM with no downtime.
• Storage DRS – Storage is managed based on performance policies. Intelligent storage resource load balancing makes use of different storage clusters to improve overall I/O.
• Fault Tolerance allow a second instance of VM’s to be ready running on a separate host ready to takeover if the first host fails. (There are currently limitations to this such as only a single vCPU).
• Integrated Disaster Recovery and Backup toolset provides a powerful feature rich back up regime that can ensure VM’s are backed up appropriately.
• vConvertor is a stand-alone tool from VMWare that can perform P2V and also import other format VM’s into vSphere.
• Built-in Firewall on the hypervisor to protect against basic threats.
• Memory over commitment using Transparent Page Sharing allows you to allocate more memory to VM’s than physically available on the host.
• Hot Add allows vCPU, memory or device to be added to a VM without downtime.
Installing vSphere Hypervisor on the hosts is a straight forward wizard driven process and can take less than 15 minutes per host. vCenter also has an easy initial setup on a server which can be either physical or virtual.
Installation of vSphere 5 can be simple in small environments but as environments grow can become more complicated. This is because all settings are stored on a central vCenter server and each host added to vCenter needs to be setup individually. This can be complicated in larger environments and also time consuming. An advantage that vCenter has to offer is called vConvertor. It is a free industry proven tool that can be used to P2V existing servers, it also has the ability to import disks in VHD format from Citrix or Microsoft environments. This makes migrating to vSphere much simpler.
Customers are able to upgrade from older versions of ESXi to VMWare vSphere 5. However there is no supported upgrade path from ESX.
VMWare vSphere 5 is managed from a centralised management console that provides unified management of all the hosts within the datacentre. A VMWare vSphere Server is used to install vCenter on and this becomes the server that manages and controls the entire site. It provides access to all the features mentioned above through a GUI interface making administration tasks easier. vCenter has the ability to add further add-ins to integrate partner solutions into the vSphere environment, this is an ideal way to add further functionality to the virtualisation environment. As VMware has a large user community and many partners there are a high number of available add ins already on the market.
Initially the performance is heavily dependent on the hypervisor and capability of making the most out of the hardware that it sits on. To do this VMWare rely on producing optimised drivers that sit directly on the hypervisor.
In larger environment’s where there are a high number of hosts features such as vSphere DRS (Distributed Resource Scheduler), vSphere Storage DRS, vSphere Storage/Network I/O Control play a big role in effectively managing the given hardware resources to meet performance criteria for VMs.
vSphere DRS – Aggregates the available resources across the clusters and then dynamically allocates them to VMs based on performance requirements and business priorities. This improves service levels for all applications on the virtualisation platform and makes it easier to deploy new resources across the system. vSphere DPM (Distributed Power Management) ensures that the cluster uses power efficiently.
vSphere Storage DRS – Uses automated load balancing based on the storage characteristics to determine the best place to store VMs disks based.
vSphere Storage I/O – Provides priority access to storage resources based on a predefined storage policy. This can move storage when a certain store becomes a bottleneck.
vSphere Network I/O – Provides priority access to network resources based on a predefined network policy. This can move network I/O when a certain channel becomes a bottleneck.
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