how to remove usb-storage devices without CAM errors

[Alban Hertroys]

On 8 August 2013 05:56, Michael Schuh <michael.schuh at gmail.com> wrote:

> ugen3.2: <Verbatim> at usbus3
> umass0: <Verbatim STORE N GO, class 0/0, rev 2.10/1.10, addr 2> on usbus3
> umass0:  SCSI over Bulk-Only; quirks = 0x0100
> umass0:8:0:-1: Attached to scbus8
> da0 at umass-sim0 bus 0 scbus8 target 0 lun 0
> da0: <Verbatim STORE N GO PMAP> Removable Direct Access SCSI-6 device
> da0: 40.000MB/s transfers
> da0: 7385MB (15124992 512 byte sectors: 255H 63S/T 941C)
> da0: quirks=0x2<NO_6_BYTE>
>


> ugen7.2: <Verbatim> at usbus7
> umass1: <Verbatim STORE N GO, class 0/0, rev 2.10/1.10, addr 2> on usbus7
> umass1:  SCSI over Bulk-Only; quirks = 0x0100
> umass1:9:1:-1: Attached to scbus9
> da1 at umass-sim1 bus 1 scbus9 target 0 lun 0
> da1: <Verbatim STORE N GO PMAP> Removable Direct Access SCSI-6 device
> da1: 40.000MB/s transfers
> da1: 7385MB (15124992 512 byte sectors: 255H 63S/T 941C)
> da1: quirks=0x2<NO_6_BYTE>
>


> (da0:umass-sim0:0:0:0): WRITE(10). CDB: 2a 00 00 02 44 80 00 00 80 00
> ugen3.2: <Verbatim> at usbus3 (disconnected)
> (da0:umass-sim0:0:0:0): CAM status: CCB request completed with an error
> umass0: (da0:at uhub3, port 3, addr 2 (disconnected)
> umass-sim0:0:0:0): Retrying command
> (da0:umass-sim0:0:0:0): WRITE(10). CDB: 2a 00 00 02 44 80 00 00 80 00
> (da0:umass-sim0:0:0:0): CAM status: CCB request completed with an error
> (da0:umass-sim0:0:0:0): Retrying command
>

I'm mostly guessing, but what I suspect that happens is that after you
successfully remove da0, the former da1 becomes da0 and any operations on
da1 (or da2 that now became da1) get aborted.

That you just happen to have exactly identical USB sticks in this case does
not help diagnosing whether that's the case though.

I'm really hoping this isn't actually what happens here, but it would
explain what you're seeing.

-- 
If you can't see the forest for the trees,
Cut the trees and you'll see there is no forest.