[Linux-cluster] dm_multipath and failover

[Stefan Majer]

Hi,

>
>   Not strictly a clustering question, but
>
>   I have for RHEL CS servers connected to an EMC CX300. QLA2432 fibre
> channel controllers.
>
>   The cards have two FC channels. I've used them to run a redundant
> fabric - there are two fibre channel switches, that each connect to one
> of the EMC's FC ports - so there are two paths to the storage. A link or
> switch can fail, but the hosts still can see the storage.
>
>   The redundancy works fine - I can pull a fibre out and the hosts can
> see the storage fine. Syslog gets spammed with lots of scsi errors, but
> dm_multipath does its stuff and the server keeps running.
>
>   However if I plug that fibre back in, the path doesn't come back. So
> far the only way to get the path back i've found is to reboot the server.
>   Is there any way to tell the controller the path is back ?.

please check if "service multipathd" returns "running"

the multipathd checks the availability of your paths and reclaims them as
active after a failure.

>   I have noticed that if i'm in this state, rebooting the McData FC
> switch will also restore the channel - it's like the switch sends some
> sort of re-initialise channel signal as it reboots.
>
>
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-- 
Stefan Majer