topic Re: Multipulse and udev in XP Storage

Multipulse and udev

Nick M_1 — Mon, 29 Oct 2007 16:56:47 GMT

Dear All

I am interested in a Red Hat path management solution for use with a XP array.

I am considering using Multipulse, but I have had difficulty finding enough information explaining how to configure Multipulse.

A document called “Emulex Multipulse for Linux User Manual” gave me enough information to install emulex Multipulse on my test server and configure the underlying devices to use Multipulse.

Unfortunately the paper provided doesn’t discuss the udev / device configuration to use with Multipulse. What happens above Multipulse – at the file system level?

Before I can use Multipulse on a production system, I need to understand how I configure Red Hat to handle the operating systems view of devices? More specifically how do I set up udev to maintain persistent names in a Multipulse environment?
Typically I’d expect to set up a udev rules file to define persistent device names for underlying multipath devices.

(For an alternate technology called device mapper I have been able to locate documents describing the set up of persistent names for multipath devices).

I’d be grateful if you could provide some guidance / URLs

Thank you

Nick

Re: Multipulse and udev

Bharath_Pingali — Wed, 31 Oct 2007 12:57:01 GMT

Hello Nick,

Which version of RedHat are you planning to use?

MultiPulse is currently supported on 2.6 Kernels, not sure about RHEL 5 or SLES 10.

Unfortunately the paper provided doesn t discuss the udev / device configuration to use with Multipulse. What happens above Multipulse at the file system level?

Once you install the kit using "./INSTALL -m", MultiPulse will automatically configure multipathing for Emulex based adapter Luns.

After the MultiPulse is loaded, the multiple paths to the same lun will be combined into one and presented to the OS.

So for udev configuration, you will have to configure as you do for any regular device.

If you are using new version of OS, Udev rules are already present.
Devices are located under /dev/disk.
by-id, by-path, by-uuid........

Device names and location can be changed from udev rules file.

This will ensure that the device name will be persistent across reboots.

Before I can use Multipulse on a production system, I need to understand how I configure Red Hat to handle the operating systems view of devices? More specifically how do I set up udev to maintain persistent names in a Multipulse environment?

Bharath - Same as above.

HBAnyware is GUI interface for viewing/changing MultiPulse configuration and devices.
It can also be used to update firmware and BIOS.

Let me know if you need more info.

-Thank You
Bharath

Re: Multipulse and udev

Nick M_1 — Wed, 31 Oct 2007 17:00:41 GMT

Bharath

That's helpful. I'll try setting up this up soon, but first please could you answer these questions -

* Is there a specific filename in "/etc/udev/rules.d" (e.g. 50-udev.rules ) that would be automatically called to set up these names ?

* For LVM pvcreates - would I create the the physical volumes on "/dev/disk/by-id" (I can see devices under "/dev/disk/by-path") ?

* Does Multipulse call udev to set up these persistent names? Are all calls to create persistent names just done via normal system calls to udev?

Many Thanks

Nick

Re: Multipulse and udev

Bharath_Pingali — Thu, 01 Nov 2007 11:01:06 GMT

Hello Nick,

Is there a specific filename in "/etc/udev/rules.d" (e.g. 50-udev.rules ) that would be automatically called to set up these names ?

The file that has the rules for â sdâ devices is â 51-by-id.rulesâ (contents below).

KERNEL="sd*[!0-9]", PROGRAM="/sbin/scsi_id", SYMLINK="disk/by-id/scsi-%c"
KERNEL="sd*[0-9]", PROGRAM="/sbin/scsi_id", SYMLINK="disk/by-id/scsi-%c-part%n"
KERNEL="sd*", PROGRAM="/sbin/path_id", SYMLINK="disk/by-path/%c"

* For LVM pvcreates - would I create the the physical volumes on "/dev/disk/by-id" (I can see devices under "/dev/disk/by-path") ?

I would use â "/dev/disk/by-id".

* Does Multipulse call udev to set up these persistent names? Are all calls to create persistent names just done via normal system calls to udev?

My understanding is that udev doesnâ t care about MulitiPulse. As OS can see only one Lun and udev uses that Lun.

Hope this helps.

-Good Luck
Bharath

Re: Multipulse and udev

Nick M_1 — Thu, 01 Nov 2007 13:05:35 GMT

Bharath

I much appreciate your help

I'll try it myself now

Many Thanks

Nick