[stgt] [PATCH 15/15] Remove dummy RAID controller from LUN 0

Boaz Harrosh bharrosh at panasas.com
Wed Nov 25 16:42:04 CET 2009


On 09/09/2009 12:30 AM, Arne Redlich wrote:
> Tomo,
> 
> Thanks for merging the other patches.
> 
> Did you come to a conclusion on this one?
> 
> Arne
> 
> Am Dienstag, den 09.06.2009, 18:23 +0200 schrieb Arne Redlich:
>> The dummy RAID controller serves 2 purposes:
>> (1) commands that are addressed to an inexistent LUN are redirected to it
>> (2) it provides a LUN 0 by default which is required by the SCSI spec
>> .
>>
>> (1) is obviously wrong because instead of "wrong lun" "invalid cdb" is returned
>> to the initiator. A "shadow LUN" of type NO_LUN is now used for this purpose.
>> This LU uses bs_null as backingstore, so there are no idle threads spawned for
>> it (in contrast to the previous dummy raid controller at LUN 0).
>>
>> (2) confuses some OSes / users (Windows prompts for drivers,
>> Solaris repeatedly tries to online the LU, but does not succeed).
>>
>> It's now the user's responsibility to attach a LU to LUN 0 to adhere to the
>> SCSI spec (Solaris / WinXP don't insist, Linux does!).
>>
>> Signed-off-by: Arne Redlich <arne.redlich at googlemail.com>
> 

What was the final disposition on this patch. I've never seen an argument against it,
but it was never submitted either. Why not?

The way I see it. It should be accepted. Since we have a configuration file arrangement
in place, which is the recommended way to work now days. And since we have "service"
scripts for major distros. Then all we need is that the startup script check, if there are
no targets defined, then simply not to load. If there is a minimum of 1 target defined
then we are fully compliant with SCSI spec in regard to LUN 0.

On the error path we are covered by this patch.

Please advise
Boaz
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