Reference Architecture

vStart 100 and 200 Reference Architecture
Dell Inc. 16
6 Scalability
When adding additional servers or storage to the rack, power, rack space, weight, and cooling
requirements must be taken into account. The power limits of PDUs and UPSs must be understood
prior to installing a new system.
Switch ports on both the LAN and SAN switches are available for expansion. Those ports must be
enabled and configured to support the new servers and/or storage arrays.
6.1 Adding new servers to the Hyper-V Cluster
If additional VMs will be deployed that will exceed current resource capabilities, or the Hyper-V cluster
has reached its acceptable maximum (CPU and memory) resource utilization, then additional servers
can be added to the cluster up to a maximum of 16 nodes depending on the rack and datacenter
capacity. See the Limitations for using Hyper-V and Failover Clustering section for more information at
this link http://technet.microsoft.com/en-us/library/cc732181(WS.10).aspx
Previously created iSCSI volumes on the EqualLogic array may require modifications to the access
controls to grant access to the newly added servers.
When adding servers to a Hyper-V cluster, it is recommended that the configuration be identical to the
other systems in the cluster. If this is not achievable, there may be restrictions on certain actions,
such as Live Migration between the differing systems. To understand Live Migration compatibility
requirements, refer to the Microsoft whitepaper, Windows Server 2008 R2 Hyper-V Live Migration
Overview and Architecture, available at
http://www.microsoft.com/download/en/details.aspx?id=12601.
6.2 Adding new storage to the EqualLogic group
New EqualLogic arrays can be added to the existing EqualLogic group. As each new array is added to
the storage group, the storage capacity and performance, in terms of both bandwidth and IOPS, are
increased. This increased capacity can be utilized without downtime. When a new array is added to an
existing pool, the existing data will automatically be distributed to the newly added array.
If EqualLogic thin provisioning was utilized and virtual capacity allocated is nearing the limit of physical
capacity, adding an additional storage array to the constrained pool will address this issue. The impact
to the total iSCSI session count for the EqualLogic group and pools must be also be understood when
adding either new servers or EqualLogic arrays.