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Mapping volumes to an ESXi server
33 Dell EMC SC Series: Best Practices with VMware vSphere | 2060-M-BP-V
Volume: "LUN20-vm-storage" → Mapped to ESX1/HBA2 -as- LUN 20 (Standby)
This example would cause all I/O for both volumes to be transferred over HBA1.
Example 2 (good example):
Volume: "LUN10-vm-storage" → Mapped to ESX1/HBA1 -as- LUN 10 (Active/Preferred)
Volume: "LUN10-vm-storage" → Mapped to ESX1/HBA2 -as- LUN 10 (Standby)
Volume: "LUN20-vm-storage" → Mapped to ESX1/HBA1 -as- LUN 20 (Standby)
Volume: "LUN20-vm-storage" → Mapped to ESX1/HBA2 -as- LUN 20 (Active/Preferred)
This example sets the preferred path to distribute the load between both HBAs.
Although the fixed multipathing policy gives more fine-tuned control over pathing, manual validation is
required to ensure that all paths have proportional amounts of traffic to each ESXi host.
6.11 Multipathing using a round robin path selection policy
When using round robin, it will provide path failure protection and will remove some of the guesswork of
distributing load between paths manually. To reiterate from previous sections, when using round robin, be
sure that the paths are of the same type, speed, and have the same queue depth setting.
Example 1:
Volume: "LUN10-vm-storage" → Mapped to ESX1/HBA1 -as- LUN 10 (Active)
Volume: "LUN10-vm-storage" → Mapped to ESX1/HBA2 -as- LUN 10 (Active)
Volume: "LUN20-vm-storage" → Mapped to ESX1/HBA1 -as- LUN 20 (Active)
Volume: "LUN20-vm-storage" → Mapped to ESX1/HBA2 -as- LUN 20 (Active)
Storage traffic is evenly distributed between all HBAs.
6.12 Asymmetric logical unit access (ALUA) for front-end SAS
The ALUA protocol was designed for arrays that VMware classifies as asymmetrical storage systems.
Historically, since the SC Series array is considered an active/active storage system where all the paths to
standard volumes are always active (unless a path failed), ALUA was not necessary.
However, with the introduction of the SAS protocol to Dell Storage SCv2000 series arrays, ALUA became
necessary for implementation into the front-end target ports for controller failover purposes. For example, for
the path to the controller where the volume is active, ALUA will set the path state as active-optimized. For the
path to the secondary controller, ALUA will set the path state to standby. During a controller failover, the
ALUA path state will change such that the secondary controller will become the active-optimized path.
The other protocols supported by SC Series storage such as Fibre Channel, iSCSI, and FCoE, the pathing
architecture remains mostly unchanged. Consistent with the former architecture, all the volume paths to the
controller that the volume is active on will be labeled active-optimized. Because SC Series storage does not