Linux qla23xx failover driver and EVA Connectivity (X-Post from disk array forum)

[noldi]

Hello,

I've installed a RedHat EL 4.0 ES Server with
the FCA-2214 HBA (Dual Channel) and the
HP Qlogic failover driver.

On the storage side, there is an EVA-3000
presenting a LUN to this server.

So far, depending on which controller the
LUN is active, I see these devices with
"fdisk -l":

LUN is active on controller A:
/dev/sda1
/dev/sdc1

LUN is active on controller B:
/dev/sdb1
/dev/sdd1

Now how does the QLogic failover driver
come into play here? - How do I see which
path is active and which is passive?

How many paths are active at any one time
(i.e. is there some kind of load balancing
involved) and how can I control this?

Would it make sense if I use the software
raid driver (md) to tie all 4 devices together
or is the failover capability handled by the
QLogic device driver?

If I have an EVA-4000 in AA-mode as opposed
to the EVA-3000 in AP-mode, how does this
influence the way things are done?


Thank's much & Regards,

Arnold Sutter, Tristar/redIT

[Uwe Zessin]

You have not configured the Qlogic device driver to use its own MPIO, else you would see only one 'sdX' device. Check the 'set_param' script to alter the setting (and say 'hello' to Uli ;-)

[noldi]

Hello Uwe,

thank's much for your response.

Unfortunately, I do not find a command/script
called 'check_param'. I have installed these
rpm-kits:
hp_qla2x00src-8.00.02-15
hp_sansurfer-2.00.30b36-1
scli-1.06.16-20

but I don't find anything similar to your
command under /opt/

Best Regards,

Arnold

[Uwe Zessin · Accepted solution]

I've unpacked 'hp_qla2x00-2005-05-11.tar' from HP's web page and ran:
# ./INSTALL

That activated the MPIO for me. As this installation was supposed to run with Secure Path I went to:
'/opt/hp/src/hp_qla2x00src'

and ran the 'set_parm' script - looks like I've put an 'a' too many into the name, sorry.

[noldi]

Hello Uwe,

indeed, I've found
/opt/hp/src/hp_qla2x00src/set_parm
and let it run with this option
"1) XP/MSA/EVA Failover"

This gave me 1 LUN over 4 Paths and I would
believe that the failover driver is manageing
the activce paths.

I've done this with an EVA-3000 and an EVA-4000
LUN and both seemed to communicate with the
host over 1 path only.

Question: is there a way to use multiple
paths concurrently or is this a strict
failover solution only where one path of
the 4 available is communicating at any one
time?

Thank's again & Regards,

Arnold Sutter, Tristar/redIT

[Uwe Zessin]

There doesn't seem to be any dynamic load balancing as in Secure Path. According to the manual, a parameter named 'ql2xlbType' exists. After reading the description it sounds like the device driver makes a round robin static path selection for different virtual disks, e.g.:
- VD1: A-FP1
- VD2: A-FP2
- VD3: B-FP1
- VD4: B-FP2
- VD5: A-FP1
...

But this only works on the EVA XL.

[noldi]

Hi Uwe,

thank's much for your persistence.

One last question: where do I find the
appropriate manuals that you were mentioning?

Best Regards,

Arnold Sutter, Tristar/redIT

[Uwe Zessin]

Oh, sorry. It's hidden a bit in the 'Other Multi-Path' section:
http://h20000.www2.hp.com/bizsupport/TechSupport/DocumentIndex.jsp?contentType=SupportManual&locale=en_US&docIndexId=179166&taskId=120&prodTypeId=12169&prodSeriesId=421487

I was talking about AA-RVGWD-TE.

[noldi]

Thank's Uwe.

Your referenced document does indeed explain a
few things.

I still didn't find out what path is currently
selected (apart from checking the switch ports
for traffic) and how to move traffic from
one path to another. Maybe this is only
possible with SecurePath.

Thank's again & best Regards,

Arnold

[Matt Tourney]

I just wanted to thank all of you who contributed to this thread. I just had the same issue today and you guys helped me out of a jam!!!!

Matt