Any application which directly needs to access the hardware without going through the OS layer will suffer in a VM environment. For ex: Games.
VMs are not good for playing games... as there are three extra layers between the games and the hardware. Host OS, VMware application and the Guest OS.
The graphics in VMWare have a generic driver. As of now the VMWare supplied graphics driver can not be replaced with a fast one. So the limitation on graphics will affect the graphic intensive applications.
Known limitations of VMware ESX server, as of May 2009, include the following:
Some limitations in ESX Server 4 may constrain the design of data centers:
- Guest system maximum RAM: 255 GB
- Host system maximum RAM: 1 TB
- Number of hosts in a high availability cluster: 32
- Number of Primary Nodes in ESX Cluster high availability: 5
- Number of hosts in a Distributed Resource Scheduler cluster: 32
- Maximum number of processors per virtual machine: 8
- Maximum number of processors per host: 160
- Maximum number of cores per processor: 12
- Maximum number of virtual machines per host: 320
- VMFS-3 limits files to 262,144 (218) blocks, which translates to 256 GB for 1 MB block sizes (the default) or up to 2 TB for 8 MB block sizes. However you should be aware that on a VMFS Boot drive, it is very difficult to use anything other than 1 MB Block size.
In terms of performance, virtualization imposes a cost in the additional work the CPU has to perform to virtualize the underlying hardware. Instructions that perform this extra work, and other activities that require virtualization, tend to lay in operating system calls. In an unmodified operating system, OS calls introduce the greatest portion of virtualization "overhead".
or other virtualization techniques may help with these issues. VMware invented the Virtual Machine Interface
for this purpose, and selected operating systems currently support this. A comparison between full virtualization
for the ESX Server shows that in some cases paravirtualization is much faster.
VMWare is most suitable for Enterprise solutions and in Data Centers. Database Servers can be run more effectively on VMs. See the links below.
Virtualizing Microsoft SQL on VMware vSphere
Oracle: Database on VMWare vSphere
VMWare is one of the better virtualization platforms around, and is quickly replacing full hardware dedicated servers.
For more information on VMWare please visit the VMWare