Why not just pull the fibre cables to get it out of the boot loop? I guess you might be booting from SAN.

To remove the PER flag from a device, you can do this using the following symconfigure command:

symconfigure -sid XXXX -cmd "set device YYY attribute=no scsi3_persist_reserv;" commit

To add the flag back:

symconfigure -sid XXXX -cmd "set device YYY attribute=scsi3_persist_reserv;" commit

Changing this setting will cause this disk to fail on all nodes of a Windows 2008 cluster so be aware that this will potentially cause DU.

Hope this helps.