Dell PowerVault MD3660i - Manual (Page 10)

Redundant And Non-Redundant Configurations
Non-redundant configurations are configurations that provide only a single data path from a host to the storage array.
This type of configuration is only recommended for non-critical data storage. Path failure from a failed or removed cable,
a failed HBA, or a failed or removed RAID controller module results in loss of host access to storage on the storage
array.
Redundancy is established by installing separate data paths between the host and the storage array, in which each path
is to one of the two RAID controller modules installed in the storage array. Redundancy protects the host from losing
access to data in the event of path failure, because both RAID controller modules can access all the disks in the storage
array.
Direct-Attached Configurations
You can connect the Ethernet ports of the host servers directly to the storage array RAID controller module iSCSI ports.
The following figure shows four stand-alone hosts supported in a dual controller array configuration with a single data
path.
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