Multiple instances of the same LUN enumerated on a host

This document (3923706) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10
EMC Symmetrix Storage Array

Situation

The Linux SCSI subsystem finds multiple instances of the same Logical Unit Number of an attached EMC Symmetrix storage array.

Resolution

Add the kernel boot optionscsi_mod.dev_flags=EMC:SYMMETRIX:0x20240to theINITRD_MODULESparameter list in/etc/sysconfig/kernel. After saving the file, runmkinitrdto create a new initial ramdisk. The parameter will become effective on the next boot of the system. To apply the changes to a running system without a reboot, run as userrootthe command echo 'EMC:SYMMETRIX:0x20240'>/proc/scsi/device_info and then rescan the SCSI bus by executing echo '- - -'>/sys/class/scsi_host/hostX/scan (replace the"X" in "hostX" with the number of the host adapter.)

Additional Information

The EMC Symmetrix storage array reports both SCSI2 and SCSI3 capabilities. Using SCSI2 capabilities results in a LUN reported more than once. A future update of the Linux kernel might blacklist the SCSI feature causing this.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.