LUNs and LUs
Posted Feb 25, 2005 17:44 UTC (Fri) by giraffedata
In reply to: Multipath support in the device mapper
Parent article: Multipath support in the device mapper
In most cases, it's just intellectually irritating when people call SCSI logical units LUNs (LUN = logical unit number). But when you're talking about a complex network like this with multiple paths, it's downright confusing. If there are 8 paths to a LU, the LU could have 8 different LUNs.
People started counting storage equipment by counting LUNs because it solved the ambiguity of what you consider one unit. Like counting spindles of disk or heads of sheep (even though you aren't actually interested in the spindles or heads themselves). Now, it doesn't solve any ambiguity and using a LUN as a metaphor for the function of a logical unit is just wrong.
Speaking of identifying units, I notice that you plug your fibre channel cables into a "solution." I wonder if that's something technical people would know better by an older name, such as "subsystem" or "network."
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