[dm-devel] [multipath] meaning of "no_path_retry nn"
Hannes Reinecke
hare at suse.de
Mon Sep 7 14:43:19 UTC 2009
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
hare at suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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