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

[Hannes Reinecke]

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.

Cheers,

Hannes
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Dr. Hannes Reinecke		   Teamlead Storage & Networking
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