[dm-devel] RHEL 4.3 to Sun 6320 storage

[James Cassidy]

Andrew Elwell wrote:

> but the error log is filling up with 
>  kernel: Device sde not ready.
>  kernel: end_request: I/O error, dev sde, sector 2181037632
>  multipathd: 8:64: mark as failed
>  multipathd: cab2a01t2: remaining active paths: 1
>  multipathd: 8:64: tur checker reports path is up
>  multipathd: 8:64: reinstated
>  multipathd: cab2a01t2: remaining active paths: 2
>  kernel: Device sde not ready.
>  kernel: end_request: I/O error, dev sde, sector 3187670215
>  kernel: device-mapper: dm-multipath: Failing path 8:64.

You'll get a device not ready on the secondary/ghost path if you have
MPxIO enabled on the array.


> 
> etc. I guess I should be using something other than the default for
> prio_callout, but what?

Nothing included with the standard kernel and multipath-tools will
work if you have the 6320 array set in MPxIO mode.  You'll either
have to set the array into 'rw' mode, which I would not recommend if
you are sharing LUNs between hosts, or you can try the patches
for the kernel and multipath-tools that I've been working on.
I've attached the patches.

The first patch is to add a hardware handler to the kernel so it
can send the command to the array to enable the secondary path to
become active if there is a problem with the primary path.  Be
sure to enable the hardware handler in the config after applying
the patch and before recompiling your kernel.

The kernel patch requires the bio-sense-data.patch be applied first.
I would also recommend applying the dm-mpath-hw-handler-sense-data
patch also.  Hopefully someone comes along and produces an alternative
to the bio-sense-data patch that can get included into the standard
kernel, but until then you have to apply it yourself.


The second patch is to the multipath-tools to add priority checker
to make sure device-mapper uses the primary path if that is available.
It also adds an entry to the hardware table so that it defaults are
set correctly for a Sun T3/T4 array. There is also a path checker
included, but readsector0 might also work too.


Comments and suggestions on the patches are welcomed.

-- 
Jim


> 
> Please can someone give me hints on the correct incantation for
> path_checker, path_grouping_policy, prio_callout
> 
> Many thanks
> 
> Andrew
> 
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