Re: pvdisplay shows "Found duplicate PV" on multipath device

2010-05-03 Thread Romeo Theriault
>
> How can I resolve the "Found duplicate PV" warning/error?
>
>
It looks like this link should be able to help you.

http://kbase.redhat.com/faq/docs/DOC-2991

Essentially you'll want to create a filter in your lvm.conf file so it only
scans your multipathed disks. From your error you see it is actually
choosing one of the paths:

# pvdisplay
>  Found duplicate PV tU6s0t1wfQNQufnOqtN1KGux5JftKJSi: using /dev/sdr not
> /dev/sdq
>

You want it to use the multipath link. But from the linked article the error
is only a warning which can be ignored if it's using the correct path, but
yours is not.







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Romeo Theriault
System Administrator
Information Technology Services

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Re: to iface or not to iface?

2010-03-01 Thread Romeo Theriault
> If you do not use ifaces, then IO will be routed based on the route table.
> So I think probably, IO would go through the same NIC on the server. Is this
> what you are seeing?


I don't actually have the env. setup yet. Right now I'm just trying to
determine what would be the best way to setup the env. without creating
another subnet for the iscsi SAN traffic.


> If you wanted to use dm-multipath to round robin over both NICs on the
> linux server then you would use a ifaces to bind each session to each NIC.
>
>
Ok, good to know.


> Are the two switches connected to each other? If they were and you are
> using one subnet, you would have better redundancy. Above you have 2 paths
> to the target, but if the switches are connected you have 4 paths.
>
>
I'm not sure I'll check this out with the networking crew.


> The network layer should figure out there is another NIC that can be used
> and just use it. A problem might be while we are switching nics IO could
> time out and both paths could be down if they both ended up using the same
> nic due to the routing table. So you would want to setup dm-multipath with a
> higher no_path_retry, because when you switch over you might also have to
> relogin to the target through the new nic.
>
> If you used ifaces then the failover should be smoother. The other path
> would already be logged in, so dm-multipath could just restart the IO right
> away.


Perfect, this is exactly the information I was looking for. Thank you for
the help, I really appreciate your response.

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Re: read only access on 1 LUN for multiple initiators

2010-03-01 Thread Romeo Theriault
> so is GFS the only option?
>

Is NFS an option?



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