Owner`s manual

NetworkingBestPracticesforVMwareInfrastructure3onDellPowerEdgeBladeServers
You can also connect multiple blade chassis together. If the total number of front-end switches is less than 8 for
Cisco, or 12 for Dell, then you can stack all the switches together into a single Virtual Blade Switch. Multiple
Virtual Blade Switches could be daisy-chained together by creating two EtherChannels.
3.4 iSCSIStorageAreaNetwork(SAN)
The iSCSI SAN traffic includes the traffic generated between the ESX Servers and Storage Arrays. This section
provides the best practices to configure iSCSI SAN including storage connectivity, load balancing, and external
connectivity using uplinks.
The following figure illustrates the virtual switch configuration with port groups and how the virtual switch is
connected to the physical network adapters and in turn to the I/O modules.
Figure 5 is based on ESX. If ESXi is used, you need not configure the service console port group for iSCSI.
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Figure6:VirtualSwitchforSANonHalfHeightBladeServers
Figure7:VirtualSwitchforSANonFullHeightBladeServers
3.4.1 LoadBalancing
To understand load balancing, it is important to understand the basics of iSCSI and how it is implemented in
VMware ESX/ESXi. Load balancing configuration depends on the iSCSI storage device that is being used.
Following are some key fundamentals that will you help understand how load balancing works:
• ESX software iSCSI initiator establishes only one connection to each target.
• The current ESX version uses only one path for each connection.
• For Dell EqualLogic SAN:
• Dell EqualLogic SAN expose each LUN or volume as a separate target with LUN ID 0. Dell
EqualLogic SAN exposes all the LUNs in a group using one IP address and hence only one path.
• EqualLogic SAN automatically load balances the LUNs between the physical interfaces in the
storage array
• In the virtual switch, the load balancing must be enabled with the configuration ‘Route based on
IP hash’
• For Dell EMC SAN:
• Dell EMC SAN exposes each physical interface as a separate target. Hence, each LUN has
multiple paths depending on the number of physical interfaces
• Multi-pathing can be achieved by manually selecting the active paths for each LUN in the vCenter
multi-pathing dialog. The paths are selected so that the LUNs are balanced across the different
physical paths.
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