Re: dm-rdac not working?

[Tore Anderson <tore@linpro.no>]

* Chandra Seetharaman

> Do you see multiple failures like shown below during the device probe
> time ?

  Yes, on all paths to the passive controller I get numerous I/O errors,
 which happens when the kernel attempts to read in the partition table,
 when LVM wants to look for PV signatures, and so on.  This is the
 behaviour I expect when using RDAC mode.

> Hmm. In my storage it is enabled. That is why I do not see that issue.
> May be multipath tools should read and ignore the stderr.

  If AVT is enabled in your storage, you shouldn't need the RDAC
 hardware handler.  When dm-multipath switches pg and starts sending I/O
 to the passive paths they should go live automatically, at least they
 do so for me...

  Bad thing about AVT is of course that when node X in a cluster boots,
 the partition table scanning will transfer the volume, making the
 active controller that e.g. nodes Y and Z was using heavily go passive,
 disrupting I/O and making everything wobbly until node X has finished
 its bootup procedure.

Regards
-- 
Tore Anderson