Conference cookie::mru

325.0. "OP:LOW Multi-call call Read Element Status with short data." by NABETH::alan (Dr. File System's Home for Wayward Inodes.) Mon Apr 14 1997 18:55

	In order to handle the inability of many OpenVMS drivers to
	transfer all the Read Element Status data for some robots,
	the OpenVMS version of mrd_read_element_status(3mrd) breaks
	up the requests when many elements are requested.

	The current check for this feature is a bit naive, only
	checking the number of elements instead of checking the
	transfer length as well.  Since the whole point of the
	exercise is to work around transfer length limits, it
	can easily check the length vs. the maximum and use
	the appropriate routine.

	A common case where this could be a problem is an 8 byte
	Read Element Status command to get the amount of data needed
	for a much larger transfer.  Today, the multi-call version
	will be used because many elements are requested and then
	it turn around and cause the command to fail because it
	doesn't think there is enough data.

	This has been fixed.  The check that decides to use the
	multi-res code also checks the length.  Both the number
	of elements and length need to be too long to use multi-
	res code.