Information Technology Reference
In-Depth Information
Figure 6.19
Only the SATPs for
the arrays to which
an ESXi host is con-
nected are loaded.
Figure 6.20
vSphere ships with
three default PSPs.
Each of these PSPs performs path selection slightly differently:
Most Recently Used (noted as VMW_PSP_MRU) selects the path it used most recently. If this
path becomes unavailable, the ESXi host switches to an alternative path and continues to
use the new path while it is available. This is the default for active-passive array types.
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Fixed (noted as VMW_PSP_FIXED) uses the designated preferred path, if it has been coni g-
ured. Otherwise, it uses the i rst working path discovered at system boot time. If the ESXi
host cannot use the preferred path, it selects a random alternative available path. The ESXi
host automatically reverts to the preferred path as soon as the path becomes available. This
is the default for active-active array types (or active-passive arrays that use ALUA with
SCSI-2 reservation mechanisms—in these cases, they appear as active-active).
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Round Robin (noted as VMW_PSP_RR) rotates the path selection among all available opti-
mized paths and enables basic load balancing across the paths and fabrics. This is not a
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