Preferred Path operation with DMP DSM
Article ID: 100020735
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When using Veritas DMP (Dynamic Multipathing) DSM (Device Specific Module) the ability to change the preferred path varies depending on the array type.
A/P hardware array, there is no preferred path setting, the preferred path is automatically detected from the array settings and displayed in the Veritas Enterprise Administrator (VEA) GUI.
Limitation for Pre SFW 5.1 SP1 is that if there is more than one path that connects to the same controller, DMP won't allow another load balancing to be used. SFW 5.1 SP1 allows different software load balancing to be used, over multiple primary paths.
A/PC hardware array, user can't change the Load Balance policy, the provided software load balance is Active/Passive only. There is no preferred path setting (Option greyed out), DMP DSM detects the preferred path of A/PC, uses the preferred path accordingly and displays the preferred path in the VEA GUI.
The automatic detection of the preferred path from the array maximizes the probability that all hosts are using the same preferred path and enables a host to send I/O through the path connecting to the preferred array controller, if there is one.
In SFW 5.1 SP1 allows different software load balancing to be used over multiple paths connected to the same controller, that is, load balancing over multiple primary paths.
A/A hardware array, the DMP DSM treats the array as A/A, and so all software Load Balancing Policies are available, including the ability to set the preferred path when using Fail Over Only (A/P) Load Balance policy.
ALUA Array, (Asymmetric Logical Unit Access) the primary path is automatically detected by SFW DSM and can't be set
On A/A-A hardware arrays, path groups are classified by the preferred path ALUA bit or A/O and A/NO ALUA state of the LUN.
On NETAPP, if the array is configured in NET APP CFO (NETAPP Cluster fail-over mode), then the array is A/PC. On NETAPP array, you can configure the array as A/A hardware type or A/P hardware type. If NETAPP array is configured as CFO, then the array is considered as A/P hardware type
Issue/Introduction
Preferred Path operation with DMP DSM
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