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How to clear SCSI reservation on a disk/LUN

If you need to clear SCSI reservation on a disk or LUN re-assigned from another system or in a "cluster installation went wrong" situation, you will find this SCSIcmd utility very useful. The SCSIcmd utility is a single .EXE file that can be downloaded from the Symantec support web site (Article: TECH72086) and can be used on MS Windows 2000, 2003, 2008 server systems.

The following SCSIcmd commands will help resolve "stuck" reservation issue:

  • Display current reservation status (make sure there is no space between -s and the SCSI command scsi_reserved_status):
scsicmd -d -sscsi_reserved_status
  • Perform SCSI-2 bus reset/break reservation:
scsicmd -d -sscsi2_clear
  • Clear SCSI-3 key and SCSI-3 reservation:
scsicmd -d -sscsi3_clear
  • Get standard SCSI Inquiry:
scsicmd -d -s12

This example illustrates how to use SCSIcmd to clear "stuck" SCSI reservation on a disk with "Unreadable" status.

C:\> scsicmd -d15 -sscsi_reserved_status

Harddisk15

Scsi Address
------------------
Length : 0x8
PortNumber : 0x4
PathId : 0x0
TargetId : 0x1
Lun : 0xe

Harddisk15 is under SCSI-2 reservation
on another SCSI Initiator/host.

C:\> scsicmd -d15 -sscsi3_clear

Harddisk15

Scsi Address
------------------
Length : 0x8
PortNumber : 0x4
PathId : 0x0
TargetId : 0x1
Lun : 0xe

Successfully performed SCSI-3 clear operation on harddisk15

C:\> scsicmd -d15 -sscsi_reserved_status

Harddisk15

Scsi Address
------------------
Length : 0x8
PortNumber : 0x4
PathId : 0x0
TargetId : 0x1
Lun : 0xe

Harddisk15 of the computer: SERVER1 is not under any SCSI reservation.