[linux-lvm] Multipath without round-robin?

[linux-lvm] Multipath without round-robin?

[Jedi/Sector One]

  Hello.
  
  I'm trying to get multipath working with LVM2 (2.6.7-rc2-udm2 kernel) with
an LSI storage array.

  The array has two FC controllers, HBAs are two identical Qlogic 2340.
  
  On the array, "preferred" controllers are assigned to each LUN.
  
  Unfortunately, it looks like dm-multipath always does round-robin load
balancing.

  The result is that the array fills up the (SANtricity) error log with
messages like "LUN was accessed through the wrong controller".

  Is there any way to keep failover abilities without load balancing?
  
  Best regards,
  
       -Frank.
       

Re: [linux-lvm] Multipath without round-robin?

[Chris Croswhite]

Decided mdadm would not do the job for you?

mdadm --create -f -lmp -n2 -x1 /dev/md0 /dev/<channela> /dev/<channelb>

This works in fail over mode by explicitly telling md to treat one as a
spare.


On Thu, 2004-06-10 at 13:33, Jedi/Sector One wrote:
>   Hello.
>   
>   I'm trying to get multipath working with LVM2 (2.6.7-rc2-udm2 kernel) with
> an LSI storage array.
> 
>   The array has two FC controllers, HBAs are two identical Qlogic 2340.
>   
>   On the array, "preferred" controllers are assigned to each LUN.
>   
>   Unfortunately, it looks like dm-multipath always does round-robin load
> balancing.
> 
>   The result is that the array fills up the (SANtricity) error log with
> messages like "LUN was accessed through the wrong controller".
> 
>   Is there any way to keep failover abilities without load balancing?
>   
>   Best regards,
>   
>        -Frank.
>        
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] Multipath without round-robin?

[Austin Gonyou]

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You could just use the qlogic hba driver failover.

ql2xfailover=1 in your rmodules.conf

Jedi/Sector One wrote:

>   Hello.
>  
>   I'm trying to get multipath working with LVM2 (2.6.7-rc2-udm2 
> kernel) with
> an LSI storage array.
>
>   The array has two FC controllers, HBAs are two identical Qlogic 2340.
>  
>   On the array, "preferred" controllers are assigned to each LUN.
>  
>   Unfortunately, it looks like dm-multipath always does round-robin load
> balancing.
>
>   The result is that the array fills up the (SANtricity) error log with
> messages like "LUN was accessed through the wrong controller".
>
>   Is there any way to keep failover abilities without load balancing?
>  
>   Best regards,
>  
>        -Frank.
>       
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>


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Re: [linux-lvm] Multipath without round-robin?

[Austin Gonyou]

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Austin Gonyou wrote:

> You could just use the qlogic hba driver failover.
>
> ql2xfailover=1 in your rmodules.conf


One caveat, if you're not running with write cache mirroring on you your 
volumes, then no matter md or qla failover, you may get data corruption. 
Some apps don't run well with it on because of the performance hit.

> Jedi/Sector One wrote:
>
>>   Hello.
>>  
>>   I'm trying to get multipath working with LVM2 (2.6.7-rc2-udm2 
>> kernel) with
>> an LSI storage array.
>>
>>   The array has two FC controllers, HBAs are two identical Qlogic 2340.
>>  
>>   On the array, "preferred" controllers are assigned to each LUN.
>>  
>>   Unfortunately, it looks like dm-multipath always does round-robin load
>> balancing.
>>
>>   The result is that the array fills up the (SANtricity) error log with
>> messages like "LUN was accessed through the wrong controller".
>>
>>   Is there any way to keep failover abilities without load balancing?
>>  
>>   Best regards,
>>  
>>        -Frank.
>>       
>>


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Re: [linux-lvm] Multipath without round-robin?

[Jedi/Sector One]

On Thu, Jun 10, 2004 at 05:06:16PM -0500, Austin Gonyou wrote:
> You could just use the qlogic hba driver failover.
> ql2xfailover=1 in your rmodules.conf

  With a 2.6 kernel (ql2xxx drivers 8.00)?

Re: [linux-lvm] Multipath without round-robin?

[Mike Christie]

Jedi/Sector One wrote:
>   Hello.
>   
>   I'm trying to get multipath working with LVM2 (2.6.7-rc2-udm2 kernel) with
> an LSI storage array.
> 
>   The array has two FC controllers, HBAs are two identical Qlogic 2340.
>   
>   On the array, "preferred" controllers are assigned to each LUN.
>   
>   Unfortunately, it looks like dm-multipath always does round-robin load
> balancing.

path0 in group0, path1 in group1 etc. When path0 fails you use path1. 
Are you using multipath-tools or settiing up the table by hand. For 
mp-tools there is a failover setting. You still cannot so explciit 
failover but that is in the works.

>   The result is that the array fills up the (SANtricity) error log with
> messages like "LUN was accessed through the wrong controller".
> 
>   Is there any way to keep failover abilities without load balancing?
>   
>   Best regards,
>   
>        -Frank.
>        

Re: [linux-lvm] Multipath without round-robin?

[Chris Croswhite]

> path0 in group0, path1 in group1 etc. When path0 fails you use path1. 
> Are you using multipath-tools or settiing up the table by hand. For 
> mp-tools there is a failover setting. You still cannot so explciit 
> failover but that is in the works.

mp-tools?

Re: [linux-lvm] Multipath without round-robin?

[Mike Christie]

Chris Croswhite wrote:

>>path0 in group0, path1 in group1 etc. When path0 fails you use path1. 
>>Are you using multipath-tools or settiing up the table by hand. For 
>>mp-tools there is a failover setting. You still cannot so explciit 
>>failover but that is in the works.
> 
> 
> mp-tools?
>

Sorry I got lazy. I wrote multipath-tools once above then just made up 
my own abbreviation. Now I have written a lot more than had I just 
written it out :) You can get the tools here btw 
http://christophe.varoqui.free.fr/

> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>