Data Mover is a hardware component of VNX for File. It reads the data from back-end storage by UltraFlex I/O technology to provide the data access. It supports NFS, CIFS and pNFS protocols. The component has scalability and redundancy.

    Data Mover failover/failure recovery mechanism is a capability of the system. If one of the devices failed and could not work normally, another device can automatically take over the work of the failed device.

Data Mover Overview

• X-Blade enclosure is Data Mover
• A VNX has up to 8 Data Movers, each X-Blade enclosure has up to 2 Data Movers
• Data Mover is something like a high-performance and high availability server
• It is used to connect to the data and network
• In the operating environment of VNX NAS side, a failover procedure will not affect the performance
• Data Mover supports hot-plug
• Support Multi-Protocol Label Switching (MPLS)
• The failure of Control Station fails does not affect Data Mover
• Data Mover does not have internal disks

Data Mover Type

• Use the command nas_server -list to show the basic information of Data Mover information:

    Type 1 stands for the primary Data Mover, type 4 stands for the standby Data Mover

• Use nas_server -a to show the detailed information of Data Mover:

Data Mover Failover

• When primary Data Mover fails, the standby Data Mover will take over the work
• Some Celerra models have only one Data Mover, in that case, it is impossible to implement failover function
• Control Station plays a monitoring role in this procedure

    When primary Data Mover fails, there comes three situations: 

Failover Policy	Description
Auto	Immediately activate the standby Data Mover
Retry	Control Station first tries to recover the primary Data Mover. If the recovery fails, the Control Station activates the standby
Manual (Default)	Control Station shutdown the primary Data Mover and takes no other action.The standby must be activated manually

    Use server_standby command to failoaver the failed Data Mover to the standby one.

    Below is how to manually activate the standby Data Mover to primary:

RCM Data Mover Failover/Failback Procedure

Failover

a.     Use nas_server -l to show the basic information of Data Mover:

b.    Restart the standby Data Mover (server_y is the name of the Data Mover)

server_cpu server_y -reboot -monitor now

c.    Use the following command to verify the standby Data Mover. Contacted means it works normally:

/nas/sbin/getreason

d.    Switch the standby Data Mover to the primary Data Mover (server_x is the name of the device)

server_standby server_x -a mover

e.     After switching the Data Mover:

nas_server -l

Failback

a.     After the failver, make sure both Data Movers are in contacted State

/nas/sbin/getreason

b.    Once the failure is fixed, restore the primary Data Mover

server_standby server_x -r mover

c.     Make sure both Data Movers are in contacted state

/nas/sbin/getreason

d.    Both two Data Movers are back to the initial state

nas_server -l

    EMC recommends that each Data Mover has a standby one. Once the primary Data Mover failed, the standby Data Mover can take over the work, ensure the host applications are working normally. Therefore, the configuration of the standby Data Mover should be same as the primary Data Mover's.