FC to SCSI Mapping
79
LUN
field, so that devices using SCC addressing can be used. In these cases, the bit fields used must be
manually configured.
For example, it may be desirable to address a FCP RAID controller using SCC Volume set addressing. In this
case,
LUN
0 would be addressed by using the
LUN
value 0x4000. Using Logical Unit Addressing, the
LUN
value would be 0x8000. Similarly, Bus 1, Target 2,
LUN
3 would be represented as 0x8243.
SCSI Address
FC Address
SCSI Bus 0, Target 0, LUN 0
Loop ID 0, LUN 0x0000
SCSI Bus 0, Target 1, LUN 0
Loop ID 1, LUN 0x0000
SCSI Bus 0, Target 2, LUN 0
Loop ID 2, LUN 0x0000
(…) (…)
SCSI Bus 0, Target 0, LUN 1
Loop ID 16, LUN 0x0000
SCSI Bus 0, Target 1, LUN 1
Loop ID 17, LUN 0x0000
SCSI Bus 0, Target 2, LUN 1
Loop ID 18, LUN 0x0000
(…) (…)
SCSI Target 7 Unavailable (Bridge Initiator ID)
SCSI-to-FCP Routing Table
Host Driver Considerations
There are a number of cases in which the host operating system or device driver expects a particular device
mapping. This is usually due to mappings being used from SCSI bus configurations. Some operating systems
map devices into internal tables that are represented as SCSI type
BUS:TARGET:LUN
triplets.
Applications that depend on this structure can be problematical. If a Fibre Channel driver is used that does
not use SCC mapping, typically devices are mapped at the Source ID (
AL_PA
) level to target devices in the
internal device map. This causes all devices behind the controller device to appear as
LUN
s to a single target.
This can have the effect of limiting the number of devices that a driver can support, or cause applications to
not address certain devices when they expect to be addressing target devices instead of
LUN
devices. Drivers
that support devices with multiple
LUN
s are particularly at risk. Flexibility in how devices are internally
mapped is necessary.
The ideal case is for host drivers to recognize controller devices from
INQUIRY
response data, and respond
by using SCC addressing to discover and map devices internally. In this type of environment, the
BUS:TARGET:LUN
combination can map directly, with a possible offset to the Bus number from that used
on the FCR router.
Summary of Contents for Scalar 218FC
Page 1: ...Installation and Operating Guide Scalar 218FC Library...
Page 6: ...vi Blank Page...
Page 101: ...Diagnostics Menu 91 Blank Page...
Page 105: ...Error Codes 95 Blank Page...
Page 123: ...113 Index...