Data Domain: Replication Network Configuration

Data Domain network configuration has many options and can be configured based on the needs in the environment. Outlined below are a few options available for use with Data Domain appliances, and some of their key features. 

Understanding each of these options and how they work is important so that the correct choice can be made for replication traffic. 

Link Aggregation Control Protocol (LACP) balancing:

LACP is static balancing based on several factors such as MAC and IP address.

As these values do not change this provides some balancing (not a dynamic balance), however LACP balancing applies to any traffic going to the Data Domain.

LACP balancing must be set up on both the Data Domain and the switch, and failure to do so can cause a significantly degraded performance.

LACP can have various hashing algorithms to dictate how the balancing takes place. Here are the supported configurations on the Data Domain:

Check the type of LACP in place by using the following command:

Net Show Settings 

-----------------
port      enabled   DHCP   IP address                  netmask          type   additional setting          
                                                       /prefix length                                       
-------   -------   ----   -------------------------   --------------   ----   -----------------------------
ethMa     no        n/a    n/a                         n/a              n/a                                
eth3a     yes       n/a    n/a                         n/a              n/a    bonded to veth0             
eth3b     yes       n/a    n/a                         n/a              n/a    bonded to veth2             
eth4a     yes       n/a    n/a                         n/a              n/a    bonded to veth0             
eth4b     yes       n/a    n/a                         n/a              n/a    bonded to veth2             
veth0     yes       no     10.xxx.x.xx                 255.xxx.xxx.x    n/a    lacp hash xor-L2: eth3a,eth4a
                           fe80::260:16ff:fe69:8c0**   /64                                                 
veth1     yes       no     10.xxx.x.xx                 255.xxx.xxx.x    n/a    lacp hash xor-L2: eth3b,eth4b
                           fe80::260:16ff:fe69:8c1**   /64                                                 
-------   -------   ----   -------------------------   --------------   ----   -----------------------------
** auto_generated IPv6 address   

In the above, physical Network Interface Cards (NICs) eth3a/eth4a are bonded together into veth0 using LACP, and physical NICs eth3b/eth4b are bonded together into veth1.

LACP balancing and the different types of LACP are discussed in greater detail in Data Domain: Setting up Link Aggregation.

Note: If a replication is only set up to a single pair of Data Domains, the impact of LACP balancing would likely be minimal. This is because the balancing factors LACP uses remain static when only replicating to one partner. Replication would most often flow over an LACP interface when the Data Domain does not have a dedicated replication network. 

Data Domain DDboost Interface groups:

DDboost interface groups (ifgroups) are a Dell proprietary balancing method to dynamically load balance the DD NICs for ddboost traffic.

For Avamar 7.2.x and older versions ifgrousp are only supported for backup traffic, but from Avamar 7.3 with DDOS 5.7 ifgroups support replication balancing as well.

• • 1. Balances ddboost traffic in real time, based on the load of individual NICs
  • 2. Ifgroups only load balance the ddboost traffic. CIFS/NFS traffic is not load balanced. LACP can serve as a better option in this case.
  • 3. The management interface should not be a member of the ifgroups. 
  • 4. If using ifgroups with replication, ifgroups should be set up on both the source and target Data Domains.
  • 5. Ifgroups with replication only apply to Managed File Replication (MFR).

DDboost ifgroups work by making an initial connection to the management interface on the Data Domain. The client is then redirected based on its ifgroup membership. 

• • Individual IP address
  • Client IP range    
  • Client hostname
  • Client Domain name   
  • All Clients

For additional information about how to setup ifgroup membership consult the administration guide for the particular DDOS version in use.   

It is also important to know that if there is a conflict or overlap between different client groups over ifgroup membership, the rules are also processed in the order listed above.

The configuration can be viewed by using the following command:

ddboost ifgroup show config all

Group Name Status     Interface  Clients
                          Count    Count
---------- --------  ---------- --------
   default disabled           0        1
      Test disabled           2        1
---------- --------  ---------- --------
Group Name Status          Interface
---------- -------- ----------------
      Test disabled    10.xxx.xxx.xx
      Test disabled    10.xxx.xxx.xx
---------- -------- -----------------
Group Name Status    Clients                                      
---------- --------  ----------------------------------------------------------------
   default disabled  *                                            
      Test disabled  testclient.company.com              
---------- --------  ---------------------------------------------------------------- 

In the above example the ifgroups are configured, but disabled, so ifgroups would not be leveraged.

For additional information about Data Domain ifgroups, see Data Domain: How do DDboost Ifgroups work on Data Domain

If a dedicated replication network is needed, and ddboost ifgroups are not possible for a dynamic balance, see Managed File Replication Over a Specific Interface for instructions on setting this up.