Infortrend S12 Series - Maximum Concurrent Host LUN Connection (Nexus in SCSI)

EonStor / EonStor DS S12/S16/S24 Series
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Maximum Concurrent Host LUN Connection (“Nexus” in SCSI)
The "Max Number of Concurrent Host-LUN Connection" menu option is used to set
the maximum number of concurrent host-LUN connections.
Maximum concurrent host LUN connection (nexus in SCSI) is the arrangement of the
controller internal resources for use with a number of the current host nexus.
For example, you can have four hosts (A, B, C, and D) and four host IDs/LUNs (IDs 0,
1, 2 and 3) in a configuration where:
 Host A accesses ID 0 (one nexus).
 Host B accesses ID 1 (one nexus).
 Host C accesses ID 2 (one nexus).
 Host D accesses ID 3 (one nexus).
These connections are all queued in the cache and are called four nexus.
If there is I/O in the cache with four different nexus, and another host I/O comes with
a nexus different than the four in the cache (for example, host A accesses ID 3), the
controller returns busy. This occurs with the concurrent active nexus; if the cache is
cleared, it accepts four different nexus again. Many I/O operations can be accessed
via the same nexus.
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