Re: [PATCH] scsi_dh_alua: Re-enable STPG for unavailable ports

[Bart Van Assche <bvanassche@acm.org>]

On 06/22/12 17:52, Moger, Babu wrote:

> One concern, the spec also says..
> ==============================
> The unavailable target port asymmetric access state is
> intended for situations when the target port accessibility to a logical unit may be severely restricted due to SCSI
> target device limitations (e.g., hardware errors). Therefore it may not be possible to transition from this state to
> either the active/optimized, active/non-optimized or standby states.
> =====================================================
> 
> What happens if we cannot transition to active/optimized, active/non-optimized or standby states.  
> Are we going to loop forever?  From kernel side it looks ok.  We are going mark the path as failed.  
> It depends on what the path checker from multipath is going to do.  Do you have any idea about it?


Good question. I'm not a multipath expert, but as far as I understand
the multipath user space software if activating a path fails after some
delay multipathd tries again to find a usable I/O path.

Bart.