redhat linux: Do we have any control on how the LUNs are discovered and named?

[Nicolas C.]

Le 12/09/2011 15:10, unix syzadmin a écrit :
> Hi,
>
> We have redhat linux servers that get SAN storage assigned from EMC.
> The LUNs are discovered as emcpowera,b etc.
> I wish they were discovered and named as ecmpower1, emcpower2 etc.
> Do we have any control on how the LUNs are discovered and named?
>
> Any ideas/suggestions is appreciated.

Hello,

/dev/emcpower* devices are created by the PowerPath software edited by 
EMC. Try using the "multipathd" packages included in Red Hat instead, it 
allows you to name your LUNs has you like.

The "/etc/multipath.conf" syntax is pretty simple (you can find the wwid 
by running "multipath -ll") :

defaults {
	user_friendly_names yes
}

multipaths {

	multipath {
		wwid	XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
		alias	your_device_name
	}

	...
}

You LUN is then available at /dev/mapper/your_device_name

One other advantage to use multipathd over PowerPath : you're sure that 
it will be working with the latest release of Red Hat. When I was using 
PowerPath, I always had to keep my Red Hat installation on the previous 
release because EMC was always 6-months late to update PowerPath and it 
wasn't working with the newer version of the kernel.

And don't worry, the fail-over functionality works very well with 
multipathd.

One last thing : by default the "/etc/multipath.conf" file blacklists 
all devices, make sure to *comment* this part of the file before starting :

blacklist {
         devnode "*"
}

Regards,

Nicolas