Force replication over specific NIC on DataDomain systems

Forcing Replication Traffic Over a Specific Network Interface (NIC)

PURPOSE

This article explains how to force replication traffic over a specific ethernet port. This may be necessary if one of the Data Domain systems moves to a different network and replication is needed to go over an alternate route.

APPLIES TO

• All Data Domain systems
• Software Releases 4.1 and later
• Replication

SOLUTION

Follow the steps below to change replication from ETH0 to ETH1. The steps must be completed on both the source and destination systems.

1. Connect to both Data Domain systems using the Command Line Interface (CLI) 180649.
2. Disable the file system (Skip this step if using DD OS version 5.0 and later).
   filesys disable

   sysadmin@test# filesys disable
   
   Please wait........
   
   The filesystem is now disabled.
   
   

3. Modify the connection host of the partner system per replication context
   
   replication modify connection-host
   Example:
   Using the IP address:
   replication modify rctx://1 connection-host 192.168.6.48
   Using the host name:
   replication modify rctx://1 connection-host neweth1
   Note: neweth1 is a hostname of the partner system on ETH1 which gets resolved into IP address 192.168.6.48 as shown above.
4. If a route needs to be added to allow the Data Domain system to connect to the partner system over the appropriate interface, see Adding a Static Route 180764.
5. Disable and renable replication (temporarily disabling all contexts). The replication service must be restarted for changes to take effect.
   replication disable all

   replication enable all
6. Verify replication network traffic is now using the new interface.
   iostat 2

   # iostat 2
   
   05/16 12:23:53
   
   INTERVAL: 2 secs
   
   "-" indicates that system is busy and unable to get recent data.
   
   -------------------------------------------------------------------------------------------------------------------------------------------  
   
   CPU  CPU  State    NFS   NFS  NFS  NFS  NFS  CIFS  eth0 MB/s   eth1 MB/s   eth2 MB/s   Disk KiB/s      Disk NVRAM KiB/s     Repl KB/s
   
   busy max  'CDBVMS' ops/s proc recv send idle ops/s in    out   in    out   in    out   read    write   busy read    write   in      out
   
   ---- ---- -------- ----- ---- ---- ---- ---- ----- ----- ----- ----- ----- ----- ----- ------- ------- ---- ------- ------- ------- -------  
   
     0%   0%              0   0%   0%   0%   0%     0     0     0     0    74     0     0       0       0   0%       0       0       0       0
   
     6%  18%              0   0%   0%   0% 100%     0     0     0     0    32     0     0       0       0   0%       0       0       0       0
   
     1%   8%              0   0%   0%   0% 100%     0     0     0     0    48     0     0       0     186   0%       0      76       0       0
   
     1%   6%              0   0%   0%   0% 100%     0     0     0     0    50     0     0       0    4137   1%       0    1685       0       0
   
   

   • The above example shows outbound network activity on ETH1 (as indicated in red).

7.  Run the command #filesys enable if your DDOS is 4.9.x and below.  For DDOS 5.0 and above Disabling the file system to perform this procedure is not required.

Note: If your problem persists after executing the steps in this article, please contact your contracted support provider, Gather an Autosupport and Create a service request