Skip to main content
Start a Conversation

Unsolved

This post is more than 5 years old

bodnarg

385 Posts

5520

February 11th, 2008 06:00

Tricks to keep Linux PowerPath devices in sequence

I think I know the answer to this question already (tough luck) but does anyone have any tricks to keep PowerPath devices under RHEL the same based on LUN number?

It appears that the newer versions of PowerPath do not use the LUN/TARGET ordering any longer which has caused some heartburn for our Linux administrators when installing newer versions of PowerPath. I found some articles to work-around this emc113184 and emc119345 and verified that this appears to be "known" behavior.

My question is does anyone have a slick way to get around this "feature" and make some Linux admins happy?

Since this is known behavior I am reluctant to open an official case on this design quirk.

xe2sdc

2.8K Posts

February 11th, 2008 06:00

Dynamox maybe I have something for your RAC clusters ... please have a look at emc94701 ... Maybe it can help to some degree..

bodnarg

385 Posts

February 11th, 2008 06:00

I did see this article, but this is basically just a different way of working around the problem instead of using that emcpadm tool which gives you a more direct way to rename devices. Looks like that emcpadm utility was only introduced in later version of PowerPath 4.x.

I'm looking more for ways to get more consistent results without having to juggle around the configuration file.

xe2sdc

2.8K Posts

February 11th, 2008 06:00

... and something also for you, Bodnarg .. :D

Have a look at emc112571 that talks about Clariion but tells the truth about emcpower devices :D

bodnarg

385 Posts

February 11th, 2008 06:00

This is aimed mostly at clustering, but also been a problem with some software updates. Meaning LUN 0 presented will translate into emcpowerA, while LUN 1 will translate into emcpowerB, etc.

On upgrades have had cases were going from version say 4.x to 5.x a device that was emcpowerA is now emcpowerC because (I'm speculating) the rules changed.

dynamox

1 Rookie

 • 

20.4K Posts

February 11th, 2008 06:00

when you say LUN/Target ordering ..what do you mean ? emcpowerX name to lun number translation ?

dynamox

1 Rookie

 • 

20.4K Posts

February 11th, 2008 06:00

i see. We had the same issue with our RAC servers, system admins had to manually rename them back to what they were before the upgrade, they were not too happy but then we don't upgrade PP too often ..sorry don't have any tips for ya.

xe2sdc

2.8K Posts

February 11th, 2008 07:00

I'm looking more for ways to get more consistent
results without having to juggle around the
configuration file.


Bonardg if I understand what the primus said, it's impossible by design.

PowerPath numbers its pseudo's based on first availability or in other words as the O/S has built the device tree based on device creation of the native devices. It is not based on the Host LUN presentation of the storage groups.

dynamox

1 Rookie

 • 

20.4K Posts

February 11th, 2008 07:00

it explains how to remedy the situation ..not a permanent fix. I have seen this behavior on a brand new installation.

xe2sdc

2.8K Posts

February 11th, 2008 07:00

You can find it in the primus .. it's something that happens on Linux and -maybe- Solaris. No other platform.

xe2sdc

2.8K Posts

February 11th, 2008 07:00

common Stefano ..don't give me excuses ..fix the
issue man :) ..get with Linus, he is geographically
closer to you then he is to us :D


Hmmm I don't really think that Linus is still in Finland ..

As per www.cs.helsinki.fi/u/torvalds/ it looks like he is in Santa Clara .. not that far from Chicago ;-)

But let me know if I have to ask my manager to set up a meeting with Linus and -hopefully- you :D

Maybe I can convert some of the points earned in the forums .. and pay me the flight :-)

xe2sdc

2.8K Posts

February 11th, 2008 07:00

Please have a look at the other primus ... they both explain (even if with different with a different accent) that each and every host will give its own name to the devices ... and that it's up to you to work around the "issue" and have the same names on both hosts :D ..

dynamox

1 Rookie

 • 

20.4K Posts

February 11th, 2008 07:00

good article, but in my case PP was not skipping names, they would simply show up in different order from RAC node to another node. Not a big deal to rename them ..but sure is annoying.

dynamox

1 Rookie

 • 

20.4K Posts

February 11th, 2008 07:00

i don't see this happening on AIX nor Windows ...must a Linux thing.

xe2sdc

2.8K Posts

February 11th, 2008 07:00

Both primus explain how to have the same names on both nodes if I understood what the primus said :D

dynamox

1 Rookie

 • 

20.4K Posts

February 11th, 2008 07:00

common Stefano ..don't give me excuses ..fix the issue man :) ..get with Linus, he is geographically closer to you then he is to us :D

View More

View All

No Events found!

Top