Re: megasas: Unexpected response from lun 1 while scanning, scan aborted

From: Hannes Reinecke
Date: Wed Mar 27 2019 - 07:31:42 EST

On 3/26/19 5:47 PM, Dongli Zhang wrote:
I am reporting an error that the scsi lun cannot initialize successfully when I
am emulating megasas scsi controller with qemu.

I am not sure if this is issue in qemu or linux kernel.

When 'lun=1' is specified, there is "Unexpected response from lun 1 while
scanning, scan aborted".

Everything works well if 'lun=0' is specified.

Below is the qemu cmdline involved:

-device megasas,id=scsi0 \
-device scsi-hd,drive=drive0,bus=scsi0.0,lun=1 \
-drive file=/home/zhang/img/test.img,if=none,id=drive0,format=raw

Below is the syslog related to 'scsi|SCSI'

# dmesg | grep SCSI
[ 0.392494] SCSI subsystem initialized
[ 0.460666] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 251)
[ 0.706788] sd 1:0:0:0: [sda] Attached SCSI disk
# dmesg | grep scsi
[ 0.511643] scsi host0: Avago SAS based MegaRAID driver
[ 0.523302] scsi 0:2:0:0: Unexpected response from lun 1 while scanning, scan aborted
[ 0.540364] scsi host1: ata_piix
[ 0.540780] scsi host2: ata_piix
[ 0.702396] scsi 1:0:0:0: Direct-Access ATA QEMU HARDDISK 2.5+ PQ: 0 ANSI: 5

When 'lun=1' is changed to 'lun=0', there is no issue.

Thank you very much!

That's an artifact from the megasas emulation in quemu.
Megasas (internally) can't handle LUN numbers (the RAID part only knows about 'disks'), so I took the decision to not expose devices with LUN != 0.
Please use a different SCSI target number, not a non-zero LUN number.


Dr. Hannes Reinecke Teamlead Storage & Networking
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