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Changing alternat disks

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Waqar Razi
Regular Advisor

Changing alternat disks

We have multipath configured for LUNs presented to servers using powerpath. Lets say if we want to change the order of the alternate paths such that the secondary becomes primary and primary becomes secondary using vgreduce and vgextend, do we need to bring the system in single user mode?

Can some one please provide me steps to do that?
4 REPLIES
Robert-Jan Goossens
Honored Contributor

Re: Changing alternat disks

Hi,

I don't understand, you are using powerpath and alternated paths (pvlinks)in your volume group setup?

couls you post a part of;

# powermt display dev=all
Regards,
Robert-Jan
rariasn
Honored Contributor

Re: Changing alternat disks

Hi,

# vgreduce vgname pv_path_primary
# vgextend vgname pv_path_primary

Do not need to bring the system in single user mode.

rgs,
Matti_Kurkela
Honored Contributor

Re: Changing alternat disks

When PowerPath is used, the order of the alternate paths has no meaning at all.

PowerPath will always override the path selection with its chosen load balancing strategy.

Check the PowerPath settings instead.

MK
MK
Ganesan R
Honored Contributor
Solution

Re: Changing alternat disks

Hi Waqar,

As people have said, LVM primary and alternate paths will not be useful when you have powerpath configured.

LVM paths will work on active passive mode. It will not do any kind of real load balancing. When active path fails it will be switched over passive paths.

Whereas in powerpath, all the I/O's will be routed through all the available paths to achieve higher throughput. It will work on active active mode.
Best wishes,

Ganesh.