[dm-devel] [RFC] training mpath to discern between SCSI errors

[Hannes Reinecke]

Sergei Shtylyov wrote:
> Hello.
> 
> Hannes Reinecke wrote:
> 
>> Actually, I think we have two separate issues here:
>> 1) The need of having more detailed I/O errors even in the fs layer. This
>>    we've already discussed at the LSF, consensus here is to allow other
>>    errors than just 'EIO'.
>>    Instead of Mike's approach I would rather use existing error codes
>> here;
>>    this will make the transition somewhat easier.
>>    Initially I would propose to return 'ENOLINK' for a transport failure,
>>    'EIO' for a non-retryable failure on the target, and 'ENODEV' for a
>>    retryable failure on the target.
> 
>    Are you sure it's not vice versa: EIO for retryable and ENODEV for
> non-retryable failures. ENODEV looks more like permanent condition to me.
> 
Ok, can do.
And looking a the error numbers again, maybe we should be using 'EREMOTEIO'
for non-retryable failures.

So we would be ending with:

ENOLINK: transport failure
EIO: retryable remote failure
EREMOTEIO: non-retryable remote failure

Does that look okay?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
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