HP Qlogic drivers

[Rikki hinn Ogurlegi]

Hello all. I have a few questions about the HP QLA drivers for Linux.

I have a rather large SAN here with two EVA8000 arrays, two EVA5000 arrays and one MSA2012 (dual controller) array.
These arrays are connected to 4 Brocade based SAN switces that are split into two seperate SANS (i.e. 2 switches pr. SAN).

Using the SAN are two rx7640 machines and one rx6600, all running RHEL4-U7 and HP ServiceGuard.

Each node has 4 Qlogic HBS's

At install time, I opted to use the Qlogic multipathing solution (HP's hp_qla2x00src-8.01.07.25-2 is in use at the moment).

It all works very well, but I do have some questions that have been lingering for quite some time in my mind.

#1: I have numerous SAN paths to each LUN and thankfully the Qlogic driver combines them all into one single /dev/sd* device.
Is there any way for me to see the status of each SAN path ?

On my HP-UX machines, I'm running SecurePath and AutoPath (depending on to which Array the machine is connected) and there I have "spmgr display" and "autopath display" to examine not only the status of each path but also what kind of load ballancing is in effect.

#2: Loadbalancing... Obviously what kind of loadbalancing, if any depends greatly on the array. Does the hp_qla driver "know" how to handle these arrays I have here correctly ?
Can loadbalancing be configured manually like I can with SecurePath/Autopath ?

#3: The SAN admin types have a bee up their bonnet for upgrading the EVA5000 arrays to the Active/Active firmware.
My understanding of the EVA5000 systems leads me to conclude that this is not a very wise Idea because of the bus connecting the two controllers in the EVA5000 is so very slow.
They counter that argument with some new Windows MPIO drivers that magicly know not to use the Active paths on the controller that does now own the LUN.
What would the end result be on the Linux servers ? I fear it could result in a major performance reduction as the other (much slower) path suddenly becomes available and used.

Thanks in advance for any comments :)

[Court Campbell]

I might have missed something but the qlogic drivers alone wouldn't do multipathing. You would need to install ans setup dm multipath. You would config the load balancing with it. Then you could view the path's,etc with the multipath command, ie, "mutlipath -ll".

[Court Campbell]

Here is a sample:

> multipath -ll
mpath2 (3600508b400104fe60000c00000070000)
[size=300 GB][features="1 queue_if_no_path"][hwhandler="0"]
\_ round-robin 0 [prio=100][active]
\_ 3:0:0:1 sdc 8:32 [active][ready]
\_ 4:0:1:1 sdf 8:80 [active][ready]
\_ round-robin 0 [prio=20][enabled]
\_ 3:0:1:1 sdd 8:48 [active][ready]
\_ 4:0:0:1 sde 8:64 [active][ready]

[Uwe Zessin]

> I might have missed something but the qlogic drivers alone wouldn't do multipathing.

I have not checked the very latest versions of HP-branded QLogic drivers, but for some time the installation routine did set up embedded multipathing, so the drivers at least _were_ able to do so.

[Court Campbell]

I know the qlogics have failover, but I don't think they do load balancing. It just reminds me of pvlinks. either way I would still recommend dm mulitpath.