[dm-devel] [multipath] meaning of "no_path_retry nn"

[Hannes Reinecke]

Diedrich Ehlerding wrote:
> I would appreciate an explanation of "no_path_retry nn" parameter in 
> multipath.conf. Probably I misunderstood it as a number of seconds. 
> 
> I am setting up  a software mirror (mdadm) on top of an EMC Clariion 
> configuration for desaster protection. The Clariions are recognized by 
> multipath properly; it seems to be set up with "no_path_retry 60" 
> (according to multipath -t). I had no further settings in 
> multipath.conf; this seems to be hardcoded into multipath. 
> 
> However, If I disconnect one Clariion, th mirror doesnt break - 
> multipath detects that all paths are failed and tells me that it will 
> now wait for 60 retries. These 60 retries seem to last very long; 
> atfter 5 minutes, it didnt complete. 
> 
> Evertyhing works fine if I set up a multipath.conf containing the 
> Clariion settings from multipath -t and modify them to 
> "no_path_retry fail" and "features 0 fail_if_no_path".  But even if I 
> just reduce the default settings to no_path_retry 2 the mirror doesnt 
> break - the IOs seem to hang indefinitely (well, I lost patience after 
> ~5 minutes).
> 
> Probably I misunderstood "no_path_retry 60" - does that mean seconds, 
> or minutes, or what else? Is anything except "fail" a useful setting in 
> mirrored configurations? 
> 
> system is a Suse  with multipath-tools-0.4.7-34.43
> 
Please note that there is a bug in the multipath-tools on suse which
prevents the no_path_retry option from working correctly.

Please install the latest maintenance update.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
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