Question on  what path status Active (I/O) / Active (I/O) means (Esxi 5 with Dell MD3220i)

Posted on 2012-09-20
Last Modified: 2014-11-15
Hi experts,

This may or may not be critical, but I would appreciate your comment on whether the behavior described below is normal and the reason behind it before moving on.

I have a setup of 2 Esxi 5 with single Dell MD3220i, HA enabled. We have configured multipathing (round robin) and everything seemed fine.

Then we started testing the HA. Before triggering the storage controller failover, the path status for the iscsi software adapter from each Esxi 5 was 1 Active, 1 Active (I/O), and 2 Standby (we have 4 paths for each host). After failover to the second storage controller, the  path status for the iscsi software adapter from each Esxi 5 was 2 Active (I/O) and 2 Standby. No matter how we rescan on the 2 Esxi 5, it stays this way.

We did not consciously set anything to cause the 2nd controller to operate on 2 ports simultaneously. Is this normal behavior or is there something that we overlooked on either the Vcenter side or the storage side? If this is normal, why the discrepancy between path status of controller 1 versus controller 2?

Many thanks

Question by:dtview
    LVL 42

    Expert Comment

    I believe that the MD 3200 is an active/passive controller so that before failover it was using controller 1, once MD3200 failed over to controller 2, controller 1 became passive and ESXi host is showing this.

    To validate please review which controller on the MD 3200i is serving data.  In general you'll have two ports active and two on standby (depending on what controller is serving data).  I haven't done too much Dell (mostly Equalogic when I did have a chance) but the concept is still the same.

    Some SAN hardware is active active so you would see all 4 ports as active if all is functioning properly

    Author Comment

    Hi paulsolov,

    Thanks for your comment.

    The 2 standby is not a problem - they all point to the non-active controller (be it controller 1 or 2), so we are quite comfortable with that. We are just puzzled by the 2 Active (I/O) on the active controller.

    A lot of the forum post have 1 Active 1 Active (I/O) and that's what we have on storage controller 1. So when storage controller 2 took over, and the active paths all become Active (I/O) we are a bit stumped.

    LVL 42

    Assisted Solution

    Since you have two nics on each controller or two iSCSI switches there are two paths to the controller.  You have configured multipathing and this is the desired result.  If you have 2 nics on each controller and two switches then all 4 ports could be active depending on how it functions.  Check the best practice for the MD3200.  I would also switch it back to controller 1 and see what happens.
    LVL 116

    Accepted Solution

    To check if your nics are being used in multipath, you can logon to the ESX console, and run esxtop, network mode, press N, and check the traffic across the iSCSI nics.

    ensure you have bound the nics for iSCSI.

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