SCSI Query - cmd_per_lun & can_queue ...

From: Shobhit Mathur
Date: Tue Jul 13 2004 - 05:42:54 EST


Hello,

I have a basic query related to the Scsi_Host_Template
fields namely : cmd_per_lun and can_queue. I would
like
to know what is the relation between the per-lun queue
and the per-HBA queue ?

To elaborate my query, I would like to know how are
the
I/Os from the upper-layers managed between per-lun and
the host-queue depth. In most cases the host-queue
depth
is very large [128 or more], while the per-lun queue
is
a fraction [5 or 2]. I would like to know how is the
relation between the two queues and how does this
impact
io-rate ?

- Kindly let me know as I have a blurred picture of
the
role of the 2 queues.

- Thank you very much

- Shobhit Mathur



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