[dm-devel] dm-rdac not working?
Tore Anderson
tore at linpro.no
Wed Aug 29 07:10:03 UTC 2007
* 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
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