Datasheet

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CHAPTER 1 VMware VSphere 4 OVerView
Virtual machines using virtual hardware version 7 features are not compatible with ESX/NOTE
ESXi releases prior to version 4.0. The virtual machine upgrade process is irreversible, and you
will see a warning window during the upgrade steps, as shown here.
di S t r i b u t e d re S o u r c e Sc h e d u l e r
VMware DRS allows you to manage physical resources distributed across multiple ESX servers.
Using DRS, you can aggregate CPU and memory resources from up to 32 ESX servers to create a
shared pool of resources, appropriately called resource pools. You can then organize these resource
pools to create a flexible hierarchy to reflect business priorities. DRS also allows you to extend the
resource management capabilities of a single ESX server such as shares, reservations, or limits to
all virtual machines within these resource pools (Figure 1.4). For example, you can assign higher
shares of the total resources to the production resource pool compared to a test and development
resource pool. Likewise, you can guarantee fixed CPU and memory (reservations) for business-
critical applications within that production resource pool.
DRS also allows you to define rules and policies for virtual machines’ resource allocations
(Figure 1.5). For example, you can define an affinity rule to make sure that all virtual machines
in a given application stack always run on the same server. All network communication for such
co-located virtual machines takes place in memory and can benefit application performance.
Alternatively, you can define an anti-affinity rule to ensure that specific virtual machines always
Figure 1.4
VMware vSphere
resource pools
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