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I'm running RHEL 5.2 connected to a NetApp over FC. The server is running a database on mpathNN devices that can not be stopped. I need to add a new LUN and give it a specific alias (rather than mpathNN). I know how to set this up in multipath.conf, but I don't know the wwid of the LUN yet. I also know this can be achieved by restarting multipathd, but don't know if this is safe.

Is it safe to restart multipathd without i/o interruption?

or, is there another way I can enable the alias specified in multipath.conf once I've presented it to the host?

thanks!

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2 Answers

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Yes, you can safely restart multipathd. It is only responsible for checking for failed paths and listening for new paths. It is not directly involved in i/o. To understand the different parts of the multipath system, read The Linux multipath implementation.

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thanks for the answer and the great link! –  carillonator Feb 28 '12 at 23:15
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Add your new alias to your multipath.conf and if you have multipathd daemon running then you can use the command multipathd -k"reconfigure"

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