Volume Manager can probe for idle LUNs (VM disks on which no I/O is scheduled) to check for their current status.  If any other process (such as VXFEN in VCS env) has a SCSI reservation on those LUNs, the system will trigger a SCSI error or SCSI reservation conflict because VxVM cannot access the LUN when it probes it.  The default time for probing for idle LUNs is every five minutes:

hostname scsi: [ID 135713 kern.warning] Warning: /path/to/the/device,0 (sd0):
hostname        offline or reservation conflict

Determine the current value of this tunable parameter with the following command:

# vxdmpadm gettune dmp_probe_idle_lun

Turn this feature off with the following command:

# vxdmpadm settune dmp_probe_idle_lun=off