[CentOS] Help setting up multipathing on CentOS 4.7 to an Equallogic iSCSI target

Fri Mar 13 22:25:24 UTC 2009
Ross Walker <rswwalker at gmail.com>

On Mar 13, 2009, at 1:50 PM, James Pearson <james-p at moving- 
picture.com> wrote:

> nate wrote:
>> Dell should be able to tell you this.
> That's what I thought ... I asked if I could get more than 2Gbit+/sec
> throughput to a single target from a single host - they said yes, but
> have not (yet) provided any useful information on how to actually set
> this up. I have a support call open, but I thought I'd ask here as  
> well
> - just in case anyone else had actually done this with this type of  
> storage.

With open-iscsi you will need to use multiple iSCSI sessions over  
different subnets and dm-multipath. Configure 2 portal addresses one  
in each subnet. If Equalogics sets the SCSI Ids correctly then dm- 
multipath will match them up. Set a round-robin policy on the paths  
and test/tune accordingly (path delays, # blocks per path, etc).

With Windows initiator you can do multiple connections over different  
subnets to the same iSCSI session which is more efficient, but I don't  
know if Equalogics supports that. You will need MS multipath for this  
to work too.

802.3ad balances hosts/connections between interfaces so each host or  
connection is limited to 1Gbps which does no good for the initiators  
but allows the target to handle more initiators if it supports it.