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How to disable a LUN PATH

 
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Emil Velez
Honored Contributor

How to disable a LUN PATH

I have a emulex card with Redhat Linux 4. The Emulex FC card does not support multipath only single path under linux.

How do I disable the other paths that the OS sees so Linux can properly see a single path to the LUN ?

Thanks for any information you can provide.Points will be provided
7 REPLIES
Ivan Ferreira
Honored Contributor
Solution

Re: How to disable a LUN PATH

>>> The Emulex FC card does not support multipath only single path under linux.

You can use device mapper multipath:

http://storagefoo.blogspot.com/2006/08/linux-native-multipathing-device.html

>>> How do I disable the other paths that the OS sees so Linux can properly see a single path to the LUN ?

That question means that you do see multiple paths to the same LUN, this is probably you presented the LUN via multiple controllers ports over the same HBA.

Depending of the storage, you could present the LUN only on one port. If you can't you should use zoning.

But anyway, probably device mapper multipath is your best option.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Emil Velez
Honored Contributor

Re: How to disable a LUN PATH

This found the device and create the /dev/mpath1-9

I cannot use /dev/mpath1-9 in fdisk commands but I can still use /dev/sdm and /dev/sdc in fdisk commands so it does not seem to disable multiple paths.

Points for other ideas.
Sandeep_Chaudhary
Trusted Contributor

Re: How to disable a LUN PATH

How do I disable the other paths that the OS sees so Linux can properly see a single path to the LUN ?


This needs to be done from Storage side.

I dont know which storage u r using. But i will simulate it with XP storage. XP storage have dual ACP pairs for redundandancy. each disk have connectivity with both the ACP card. so each lun is having two different path(frm two chip port of two ACP. Ask ur SAN administrator to assign Lun to only one host group or in case of EMC assign to one chip port. may be i have not writtren this properly as i am not SAN administrator.
Emil Velez
Honored Contributor

Re: How to disable a LUN PATH

I tried the multipathd and it creates the multipath device files but when I use lvmdiskinfo and other tools it still sees the /dev/sd files and still uses them. There does not seem to be a way to turn those files off.
Rob Leadbeater
Honored Contributor

Re: How to disable a LUN PATH

Hi Emil,

Which Emulex HBA are you using, and what storage ?

A quick Google suggests that you might be able to use the Emulex MultiPulse module...

http://h50146.www5.hp.com/products/software/oe/linux/mainstream/bin/support/doc/option/fibre/README.multipulse2164.txt

Hope this helps,

Regards,

Rob
Brem Belguebli
Regular Advisor

Re: How to disable a LUN PATH

Hi,

With DM-multipathd enabled, you may see your multipath devices ( mpath0 -- mpathXX if user_friendly_names is to yes in /etc/multipath.conf ) and their different paths (/dev/sdx).

DM-multipath manages by default persistent binding (names the do not change across reboots) in /var/lib/multipath/bindings. If /var is on a different mount point than /, things are not going to work well.

Post the multipath-ll -v2 output

Attention, /dev/sdx names are volatile, never base a configuration on these names.

Once your mpath devices are well seen, you can setup LVM based on these /dev/mpath/mpath devices.

pvcreate /dev/mpath/mpathx etc ...

I don't know nothing about lvmdiskinfo.

If you do not want to use LVM on these disks but legacy partitions (fdisk)partition your first path (/dev/sda) with the desired layout and then replicate the partitionning to the other paths :

sfdisk -l /dev/sda | sfdisk /dev/sbd ...

this will create all the /dev/sdx[-9] devices

I would use rather LVM.







Emil Velez
Honored Contributor

Re: How to disable a LUN PATH

Brem

Thanks for the suggestion. Unfortunately the application I am using "Polyserve" only sees the SDA device files and cannot be configured to use the multipath device files