Alternate Path Support in LINUX

[Sยภเl Kย๓คг]

Folks,

I have a quick question for you!.

Does linux support Alternate pathing in volume groups.

HP UNIX support Alternate paths with LVM.

Regards,
Sunil

[Ivan Ferreira]

Yes with mdadm, for example:

mdadm -C /dev/md0 --level=multipath --raid-devices=2 /dev/sda1 /dev/sdb1

But normally, multipath is provided by the HBA driver and the os sees only one physical device.

[Sยภเl Kย๓คг]

Okie.
Ivan I am sorry, few questions on mdadm.

Is it a Linux Utility(Free), or some kind of extra multipathing software.

See we have powerpath installed on all these linux boxes. We are planing to get ride of powerpath; If mdadm is free software, we are really intersted in that.

Can you please tell me how it works. Though we add multiple paths when allocating disk, it genereates only one device path /dev/sdx ( for one PV). Why is it so.

Or may be some links to get familiar with it

Thanks for your quick reply

Sunil

[Ivan Ferreira]

Normally mdadm is included in the base operating system. It's "free". But I suggest you the use of multipath HBA drivers like Qlogic.

What is the HBA model that you are using?

[Sยภเl Kย๓คг]

Hi,

We have Qlogic and Emulex cards. How will I make it with these drivers?

Regards, Sunil

[Serviceguard for Linux]

You should probably check the EMC website as well.

I'd pretty sure that MD will not work with Clariion. I think the Clariion array requires some control for failover It may work with Symmetrix.

EMC may support DM, based on the activity on the DM mailing list.

mdadm gnerally comes with most (all?) versions of Linux. It is part of RedHat and SUSE.

DM is part of RH4 and SLES9.

Both QLogic and Emulex drivers have built in multipath functionality. Not sure if they work or are supported with EMC.

[Hemmetter]

Hi Sunil,


have a look at multipath-tools.

Linux native multipathing is supported by EMC.

rgds
HGH