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List:       opensolaris-lvm-discuss
Subject:    [lvm-discuss] MPXIO on a V880
From:       prasadjlv () yahoo ! com (prasad jlv)
Date:       2006-02-24 20:07:58
Message-ID: 20060225033957.24345.qmail () web32907 ! mail ! mud ! yahoo ! com
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Hmm, I thought SVM mirrors perfomed  reads in a round-robin way too and If I am \
mirroring across  controllers, am I achieving the same? or is my assumption about \
SVM's  read policy incorrect?  
  -- prasad
  
  
  
Sanjay Nadkarni <Sanjay.Nadkarni@sun.com> wrote:  
One of the advantages of mpxio is that it load balance requests across 
the controllers. Let's assume 12 read requests occurs.  Since you have a 
mirror, they will be round-robin'ed. 6 per submirror.  Now if the 
controller on the submirror is busy processing some other I/O, then the 
read requests will be queued.  If you have mpxio, that I/O could 
potentially be dispatched from the other controller.

Of course it's obvious that your load has to be fairly high for this 
situation to pay off.


-Sanjay

prasad wrote:

> I am trying to understand the benefits of MPXIO in our situation....
> 
> We  have a V880 with the backplane expansion kit and 12 x 73 GB disks but  with \
> MPXIO disabled. format(1M) displays 24 disks with 2 paths to each  of the 12 disks \
> (c1tXd0 and c2tXd0) and we are mirroring our disks  using SVM in the following way: \
>  d500 -m d400 d700 1
> d400 1 1 c1t0d0s0
> d700 1 1 c2t8d0s0
> ..........................
> 
> My questions are:
> 
> *  Since we are accessing the mirrors thru unique controllers i.e. c1  & c2 are we \
> doing load balancing? I wonder how the system would  behave if one of the \
>                 controllers failed? 
> * How would MPXIO help in the above scenario? Are we doing something terribly wrong \
> by not enabling MPXIO? 
> TIA,
> -- prasad
> This message posted from opensolaris.org
> _______________________________________________
> lvm-discuss mailing list
> lvm-discuss@opensolaris.org
> 
> 



		
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