Receiving Sense Key : Illegal Request in ghost paths during boot

Environment

• Red Hat Enterprise Linux (RHEL)6

Issue

• During boot, the server is printing the following errors:

Dec 11 14:10:53 localhost kernel: sd 7:0:3:5: [sdf]  Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Dec 11 14:10:53 localhost kernel: sd 7:0:3:5: [sdf]  Sense Key : Illegal Request [current] 
Dec 11 14:10:53 localhost kernel: sd 7:0:3:5: [sdf]  <<vendor>> ASC=0x94 ASCQ=0x1
Dec 11 14:10:53 localhost kernel: sd 7:0:3:5: [sdf] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00
Dec 11 14:10:53 localhost kernel: end_request: I/O error, dev sdf, sector 0
Dec 11 14:10:53 localhost kernel: Buffer I/O error on device sdf, logical block 0
Dec 11 14:10:53 localhost kernel: sd 7:0:3:7: [sdh]  Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Dec 11 14:10:53 localhost kernel: sd 7:0:3:7: [sdh]  Sense Key : Illegal Request [current] 
Dec 11 14:10:53 localhost kernel: sd 7:0:3:7: [sdh]  <<vendor>> ASC=0x94 ASCQ=0x1
Dec 11 14:10:53 localhost kernel: sd 7:0:3:7: [sdh] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00
Dec 11 14:10:53 localhost kernel: end_request: I/O error, dev sdh, sector 0

These messages disappear when the module 'scsi_dh_rdac' is loaded.

Resolution

The issue can be fixed by rebuilding the initramfs image to include the 'scsi_dh_rdac' kernel module.
In the cases where the initramfs is already there, check that multipath is active. If not, follow instructions here .

Root Cause

The problem seems to be that during start up, an SCSI INQUIRY command is being sent to ghost paths, and these commands are failing as expected. When the kernel module scsi_dh_rdac is loaded, no INQUIRY is sent to ghost paths at all.

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