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Looking for Avamar Gen3 Switch Redundancy ?

June 3, 2010

Last year, when installing the EMC ADS Gen2 switch with Avamar ver 4( Gen2 hardware), I got quite a bit of customer feedback on the desire for switch redundancy. Since Avamar 5 has been out along with the Gen3 hardware that is now possible. There are 2 methods for protecting against uplink failures to your edge or core switch. One method is installing dual Gen3 ADS switches with the eth0 and eth2 Gb ports bonded together during the dpnnetutil process. The second method, which currently has a gotcha involved (will get to that in a bit) involves Static Link Aggregation between uplinks from ports 1 to 4 on the Gen3 ADS switch to your network.

The configuration for dual switches is simple enough. During the dpnnetutil process you are given the option to bond eth0 and eth2. You will then plug eth0 into switch1 and eth2 into switch2 on all nodes. So naturally you would guess for protection against a single point of failure, you would uplink the 2 switches into separate switches for redundancy, sounds logical. Unfortunately, there have been some reported issues from users with dual Avamar switches uplinked into separate switches, symptoms occurring have been loss conectivity within the Avamar Grid as well as outside network devices resulting in loss packets or incomplete transactions, I have been informed that there is no risk to data corruption on the Avamar Data Store, but backups/restore operations have been impacted. For now, the workaround is to have both uplinks from the Avamar ADS switches plugged into the same switch and same VLAN within that switch if multiple VLANs are present. EMC is currently working on a fix, but I have not been informed on an ETA.
The second method, Static Link Aggregation, involves a little more setup. For this configuration to work, the switch ports on the other end of the uplink must be configured for static link aggregation. The Avamar Gen3 install manual points out that static link aggregation is not LACP, keep that in mind – this could cause network loops. An example of setting this up on a Cisco switch is to configure EtherChannel but without PAgP, see Technical note Cisco IOS, CatOS Uplink Aggregation Examples (300-010-673) for examples. For HP Procure Switches, you would configure Trk trunk ports on the uplinked ports.
To configure the ADS switch, you will need to download the ADS_Gen3_switch_config.zip on EMC Powerlink and follow steps listed out in the Data Store Gen3 System Installation Manual. I will try to blog on the actual steps on this configuration at a later time if possible. Once ports 1-4 on the ADS switch are configured for static link aggregation, you can proceed with plugging in port 1 into your network, if you have network connectivity, then proceed with the remaining ports. Keep in mind that if you intend to just uplink 1 port that no configuration is involved, the port will auto-negotiate full or half duplex and down to 1Gb port speed.
Currently these 2 methods of uplink redundancy are only supported on the EMC provided ADS Gen3 switches.
Thanks for stopping by!


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3 comments

  1. Hi, your article is interesting. I am not a person with indepth knowledge on Avamar ADS Gen3 switches, but I hope it support following scenario: and would be great to know how to configure ADS switch to achieve this:

    1) Two ADS Gen3 switches;

    2) each node connects to two switches, bond0 ( eth0 + eth2 );

    3) each ADS switch has 4 uplink ports;

    4) switch A 4 uplink ports connect to customer core switch 1, working like a 4Gbps link also doesn’t matter if losing up to 3 physical links;

    5) switch B 4 uplink ports connect to customer core switch 2, working like a 4Gbps link also doesn’t matter if losing up to 3 physical links. it’s port to node stay as passive, but in case node port to switch A fails, this switch node port will take over

    8) uplink ports on customer switch 1 and customer switch 2 are in the same VLAN ( or SAME multiple VLANs )

    Would it be possible ?
    Note the 300-010-673 document in cisco is a broken link and could not find the document…

    Kind Regards
    Liang


    • Liang,
      I did not mention it and will modify the post, buy you can mix both methods of redundancy. After you bond the ports during the dpnnetutil process, complete the steps to configure ports 1-4 on ADS switch 1 for redundancy, then repeat the same process on ADS switch2.


  2. Why are we bing asked to utilize 10. local i/p’s on our switches? Is there a fix for this or is it still Static Link Aggregate set up?



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