Getting 'reservation conflict' errors while none of the applications on server are using SCSI reservations.

Issue

• We have Oracle RAC setup of 2 nodes where each node uses its own set of EMC Symmetrix LUNs. These LUNs are not shared with cluster nodes, and Oracle RAC is also not setup to use SCSI reservations, but still the database restoration activity results in following SCSI reservation conflict errors:

  Dec  1 21:36:03 host1 kernel: [1842327.927058] sd 12:0:3:12: reservation conflict
  Dec  1 21:36:03 host1 kernel: [1842327.927065] sd 12:0:3:12: [sdbe] tag#27 Done: SUCCESS Result: hostbyte=DID_NEXUS_FAILURE driverbyte=DRIVER_OK
  Dec  1 21:36:03 host1 kernel: [1842327.927068] sd 12:0:3:12: [sdbe] tag#27 CDB: Write(10) 2a 00 37 2c aa e0 00 00 10 00
  Dec  1 21:36:03 host1 kernel: [1842327.927070] blk_update_request: critical nexus error, dev sdbe, sector 925674208
  Dec  1 21:36:03 host1 kernel: [1842327.927850] sd 12:0:1:12: reservation conflict
  Dec  1 21:36:03 host1 kernel: [1842327.927852] sd 12:0:1:12: [sdaq] tag#36 Done: SUCCESS Result: hostbyte=DID_NEXUS_FAILURE driverbyte=DRIVER_OK
  Dec  1 21:36:03 host1 kernel: [1842327.927853] sd 12:0:1:12: [sdaq] tag#36 CDB: Write(10) 2a 00 37 41 66 f0 00 00 10 00
  Dec  1 21:36:03 host1 kernel: [1842327.927855] blk_update_request: critical nexus error, dev sdaq, sector 927033072
  Dec  1 21:36:03 host1 kernel: sd 12:0:3:12: reservation conflict
  Dec  1 21:36:03 host1 kernel: sd 12:0:3:12: [sdbe] tag#27 Done: SUCCESS Result: hostbyte=DID_NEXUS_FAILURE driverbyte=DRIVER_OK
  Dec  1 21:36:03 host1 kernel: sd 12:0:3:12: [sdbe] tag#27 CDB: Write(10) 2a 00 37 2c aa e0 00 00 10 00
  Dec  1 21:36:03 host1 kernel: blk_update_request: critical nexus error, dev sdbe, sector 925674208
  Dec  1 21:36:03 host1 kernel: sd 12:0:1:12: reservation conflict
  Dec  1 21:36:03 host1 kernel: sd 12:0:1:12: [sdaq] tag#36 Done: SUCCESS Result: hostbyte=DID_NEXUS_FAILURE driverbyte=DRIVER_OK
  Dec  1 21:36:03 host1 kernel: sd 12:0:1:12: [sdaq] tag#36 CDB: Write(10) 2a 00 37 41 66 f0 00 00 10 00
  Dec  1 21:36:03 host1 kernel: blk_update_request: critical nexus error, dev sdaq, sector 927033072
  [...]
  

• Need RCA for SCSI reservation conflict errors.