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Mapping volumes to an ESXi server
32 Dell EMC SC Series: Best Practices with VMware vSphere | 2060-M-BP-V
When using the fixed policy, if a path fails, all the datastores using it as their preferred path will fail over to the
secondary path. When service resumes, the datastores will resume I/O on their preferred path.
Here is an example of using the fixed policy:
1. HBA1 loses connectivity; HBA2 takes over its connections.
2. HBA1 resumes connectivity; HBA2 will fail its connections back to HBA1.
Example of fixed datastore path selection policy set with a preferred path
6.9.4 Most recently used policy
The most recently used (MRU) PSP is used with active/passive arrays (to prevent path thrashing). MRU is not
recommended or tested for use with SC Series storage because a volume can only be active on one
controller at a time.
6.10 Multipathing using a fixed path selection policy
Keep in mind that with a fixed policy, only the preferred path transfers data. To distribute the I/O loads for
multiple datastores over multiple HBAs, the preferred path must be set for each datastore consistently
between each host. Here are some bad and good examples:
Example 1 (bad 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 (Active/Preferred)