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How DMP interacts with MPIO.

Article: 100019054
Last Published: 2022-01-23
Ratings: 1 0
Product(s): InfoScale & Storage Foundation

Description

The articles help explain how DMP interacts with MPIO

 

Details

MPIO is a "path suppressing" driver which means that when it is enabled only one path will be visible to DMP.
 
MPIO supersedes DMP, so it will control path-failover and load-balancing.
 
Path failures will be transparent to DMP. If DMP metanodes are created and the path fails, then DMP will offline the LUN/device. This will happen because DMP will use the controller device number during its error analysis routines.                                                                                                                                            
Here's an example of the messages in the ' errpt -a' output:
 
LABEL:VXVM_VXDMP
IDENTIFIER:B258EF25
Date/Time: Tue Oct 6 19:30:03 2009
Sequence Number: 148715
Machine Id:00C926444C00 Node Id: server102
Class: S
Type:TEMP
Resource Name:VxDRV:vxdmp
Description Messages reported by vxdmp driver
Probable Causes: Attempt to disable last path to a device Failure of Open or Close to a device Path failure to one or more devices
User Causes: Disabling the last path to the controller Trying to access the device which does not exist Attempt to unload the vxdmp driver
Recommended Actions Verify whether trying to disable the last access path to a device CHECKCABLES AND THEIR CONNECTIONS
Failure Causes
Bad Disk
Adapter Error
Cable or Disk Failure

To avoid this situation, set dmp_fast_recovery to off.

# vxdmpadm settune dmp_fast_recovery=off
# vxdmpadm gettune all |grep dmp_fast
dmp_fast_recovery                      off               on

Note- The dmp_fast_recovery tunable controls whether DMP should attempt to obtain SCSI error information directly from the HBA interface. The default setting is on.
 
 
 

 

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