Question about Multibus+Failover

Question about Multibus+Failover

[Josef Whiter]

Hello,

I've had several requests about loadbalancing coupled with failover for 
dm multipathing.  I know with failover you get just failover, and 
multibus you get just load balancing, but I was wondering if there was a 
hybrid option for load balancing that would handle a failed path 
gracefully.  Thanks much,

Josef

-- 
Josef Whiter, RHCE
Global Support Services
Red Hat, Inc.
919-754-3700 x44429

Re: Question about Multibus+Failover

[Josef Whiter]

Christophe Varoqui wrote:

>On mar, 2005-12-06 at 15:37 -0500, Josef Whiter wrote:
>  
>
>>Hello,
>>
>>I've had several requests about loadbalancing coupled with failover for 
>>dm multipathing.  I know with failover you get just failover, and 
>>multibus you get just load balancing, but I was wondering if there was a 
>>hybrid option for load balancing that would handle a failed path 
>>gracefully.  Thanks much,
>>
>>    
>>
>Failed paths are handled quite gracefully in all grouping policies.
>
>That said, other stock grouping policies are at your disposal :
>group_by_serial or group_by_node_name or the special group_by_prio that
>let you do your own grouping policy with callouts (shell scripts or
>whatever).
>
>Please have a look at the documentation available.
>
>Regards,
>cvaroqui
>
>  
>
Hmm, then perhaps I've been seeing errant behavior, b/c everytime 
somebody uses multibus and they fail a path they get a bunch of IO 
errors and the FS is remounted, but if they use failover and pull the 
active connection, there are no errors and the failover is seamless.  I 
shall investigate further on what they are seeing.  Thank you,

Josef

-- 
Josef Whiter, RHCE
Global Support Services
Red Hat, Inc.
919-754-3700 x44429

Re: Question about Multibus+Failover

[Christophe Varoqui]

On mar, 2005-12-06 at 15:37 -0500, Josef Whiter wrote:
> Hello,
> 
> I've had several requests about loadbalancing coupled with failover for 
> dm multipathing.  I know with failover you get just failover, and 
> multibus you get just load balancing, but I was wondering if there was a 
> hybrid option for load balancing that would handle a failed path 
> gracefully.  Thanks much,
> 
Failed paths are handled quite gracefully in all grouping policies.

That said, other stock grouping policies are at your disposal :
group_by_serial or group_by_node_name or the special group_by_prio that
let you do your own grouping policy with callouts (shell scripts or
whatever).

Please have a look at the documentation available.

Regards,
cvaroqui

Re: Question about Multibus+Failover

[Christophe Varoqui]

> >  
> >
> Hmm, then perhaps I've been seeing errant behavior, b/c everytime 
> somebody uses multibus and they fail a path they get a bunch of IO 
> errors and the FS is remounted, but if they use failover and pull the 
> active connection, there are no errors and the failover is seamless.  I 
> shall investigate further on what they are seeing.  Thank you,
> 
May be because they use hardware that needs a hardware handler ?
The hwh trigger needs different path group, thus not compatible with
multibus.

Regards,
cvaroqui