• Configure replication using Unisphere

    PDF

    Configure replication using Unisphere

    Configure protection and mobility interfaces

    Before you begin

    Protection and mobility (import) interfaces can be shared between replication and import. For import, only VDM imports require interfaces. Block imports do not require interfaces.

    Protection and mobility (import) interfaces are configured to support VDM imports and must be created prior to creating an import connection. A mobility interface IP address is assigned to SPA and SPB on the target Unity system. Once the mobility interface is configured, you can create the import connection between the Unity system and the VNX system. Mobility interfaces are not used for block import sessions.

    Ensure the following:

    • The interface port is cabled and connected to a network switch.
    • Both SPs are up and running.

    Obtain the following information for each Storage Processor (SP):

    • IP address associated with the interface (replication or import). Although you can specify an IPv4 or IPv6-based address, ensure that you specify the same type of address for both SPs.
    • IP address mask or prefix length that identifies the associated subnet.
    • Gateway IP address associated with the interface.
    • If applicable, the VLAN ID (between 1 and 4095) you want to associate the interface with.
      Note:  For the network to continue functioning properly, ensure that you set the VLAN ID only when you have configured the network switch port to support VLAN tagging of multiple VLAN IDs.
    Procedure
    1. Under Protection & Mobility, select Interfaces.
    2. Perform one of the following actions:
      • To create an interface, select the Add icon. On the Create Interface window, specify the relevant information:
        • For asynchronous replication or import, from the Ethernet Port list, select an available Ethernet port.
        • For synchronous replication, from the Ethernet Port list, select Sync Replication Management Port.
          Note:  Do not use Sync Replication Management Port for asynchronous replication or import interfaces.
      • To modify an interface, select the interface, and then select the Edit icon. On the Interface Properties window, specify the relevant information.
      • To delete an interface, select the interface, and then select the Delete icon.
        NOTICE  Before you delete an interface, ensure that the interface is not being used by any replication or import session.

    Configure replication connections

    Before you begin

    Ensure that you have set up relevant replication interface pairs, one on each SP, on the source and destination systems. Obtain the following information:

    • For remote replication, the IP address and associated user authentication credentials to connect to the remote system.
    • For local replication, the password associated with your user account.
    • The connection mode you want to use for the replication: Asynchronous, Synchronous, or Both.
    NOTICE  If a replication connection already exists and you plan to add a different mode of file replication, do not attempt to create a new connection. Change the existing replication connection mode to Both. Also, ensure that you have the appropriate interface types configured to support both asynchronous replication (eth2, eth3) and synchronous replication (sync replication mgmt port).
    Procedure
    1. Under Protection & Mobility, select Replication > Connections.
    2. Perform one of the following actions:
      • To create a replication connection, select the Add icon. On the Create Replication Connection window, specify the relevant information.
      • To modify a replication connection, select the replication connection, and then select the Edit icon. On the Replication Connection Properties window, specify the relevant information.
      • If new replication interfaces were added, or existing replication interfaces were deleted, the remote system connection may become outdated. Select the relevant replication, and then select Verify and Update to update the remote system connection to pick up the latest replication interface changes on the local and remote systems.

    Create a replication session

    Before you begin

    Ensure that you have first created relevant replication interfaces and connections, and then determine the following:

    • The replication mode you want. You can choose from the following options:
      • Asynchronous
      • Manual
      • Synchronous
    • The Recovery Point Objective (RPO) for the replication session.
    • The system you want to assign as the replication destination system. This is based on the replication connections configured on the storage system.
    • The name, pool, storage provisioning, and tiering policy you want to use for the destination storage resource. The system will automatically create a destination storage resource as part of this process.
      Note:   You can convert a thin LUN to a non-thin (thick) LUN, or a thick LUN to a thin LUN with a LUN move operation. To enable data reduction on a thin LUN requires an All-Flash pool on the destination system. For thick file systems, the replication process matches the destination storage resource to the source. In this case, thin and data reduction cannot be selected for file systems. For thin file systems, the following rules apply for replication:
      • If the source file system is thin, then the destination file system is also thin.
      • If the source file system is thin and either the source or destination system does not support data reduction, then the destination file system is also thin.
      • If both the source and destination systems support data reduction, then the source or destination can have either data reduction enabled or no data reduction enabled.
      • However, if you change the source file system data reduction attribute, the change is not replicated to the destination system (retains the original setting) regardless of using asynchronous or synchronous replication.
    • Replicate scheduled snapshots to the destination and to use the same retention policy or a different policy. Also, when a replication session is created some time after the resource was created, determine whether to select the one-time option to replicate all existing snapshots.
      Note:  Snapshots that have been created and attached as well as read/write (share) snapshots (as opposed to read-only checkpoint snapshots) are not eligible for replication. Only unattached (read-only) snapshots are eligible for replication. For asynchronous replication, you can replicate existing snapshots and snapshots created from snapshot schedules. For synchronous file replication, you cannot replicate existing snapshots or snapshots created from snapshot schedules. You can only replicate those snapshots and snapshots created from snapshot schedules after you have established the synchronous replication session and it is Active. For synchronous block replication, you cannot replicate any snapshot.
      Note:  To do snapshot replication from a source system running OE version 4.0, 4.1, 4.2, 4.3, or 4.4 to a destination system running OE version 5.x, requires upgrading the source system to OE version 4.5 first. Upgrading to OE version 4.5 is not required but recommended if you want to do LUN or file system replication from OE version 4.0, 4.1, 4.2, 4.3, or 4.4 to OE version 5.x without any snapshot replication.

    With the advanced file asynchronous replication topologies, fan-out (star) and cascaded mode, feature introduced in OE version 5.x, up to four asynchronous replication sessions can be created on the same storage object. The following restrictions apply to this feature:

    • This feature only supports file storage objects and does not support block storage objects.
    • Only one session can be created between two remote systems.
    • All systems joining the multiple sessions, either in fan-out (star) or cascaded mode, must be running OE version 5.x.
    • Only one local or loopback asynchronous session is supported and the associated resource does not have be in destination mode.
    • When one synchronous session is created, a session should not be created from the destination side and only one remote asynchronous session should be created from the source.
    • When the storage object is created as the destination mode and one session is created on it as the destination, the storage object can be used to create another session when it acts as the source.
    • A user snapshot replication can only be supported for one asynchronous session among all the sessions associated with the same storage object.
    Procedure
    1. Under Storage, select the storage resource, and then select Edit.
      Note:  For file storage, you must first configure replication on the NAS server.
    2. On the Properties window, select the Replication tab.
    3. Select Configure Replication.
    4. In the Create a Session window, specify the relevant information.
      Once you specify the necessary information for the destination storage resource or NAS server, the system will automatically create the storage resource or NAS server on the destination system.
      Note:   On a NAS server that is protected by replication, you must create a replication session for each file system on it. Otherwise, file system related configurations like shares and exports may be lost after a NAS server replication session failover.
      • When you use Unisphere to create replication for a NAS server, the system automatically creates a replication session for each file system on it.
      • When you use Unisphere to create a new file system, Unisphere creates a replication by default.

    Manage replication sessions

    A replication session establishes an end-to-end path for a replication operation between a source and destination. The replication source and destination may be remote or local, so the session establishes the path that the data follows as it moves from source to destination.

    If you want to set up a replication session, see Configure replication.

    With the advanced file asynchronous replication topologies, fan-out (star) and cascaded mode, feature introduced in OE version 5.x, up to four asynchronous replication sessions can be created on the same storage object. The following restrictions apply to the managing replication sessions operations:

    • Delete
      • In fan-out or star mode:
        • On the source side of the replication, concurrent delete for four replication sessions is not supported. If four replication session delete operations are triggered at the same time, the operations are queued to be done one by one.
        • If the remote system is in the lost communication state, the replication session delete operation is done only on one side (source or destination). The residual replication session is visible on the remote side.
        • When the replication session on the destination side is deleted, it is removed only on the destination side, and the source side replication session state is changed to Non recoverable error.
        • If the previous replication session delete operation failed, that replication session remains visible and the delete operation can be retried. The residual replication session could be recovered and shown after a system reboot.
        • If the replication session delete failed on the source side, the replication session is already deleted on the destination side and the residual replication session is only visible on the source side. If the replication session failed on the destination side, the replication session is already deleted on the source side and the residual replication session is only visible on destination side.
        • If the replication session to be deleted is already in a Non recoverable error state caused by a previous unexpected operation, it is recommended to clean-up the replication session residual components by using the svc_dataprotection service command. It can be used to clean up a single session with the session ID or clean up the orphan components for the sessions associated to a single storage resource. If the resource is offline, it needs to recover the resource to be online, then continue the deletion.
          Note:  For more information about the svc_dataprotection service command, see the Unity Service Commands Technical Notes.
      • In cascade mode:
        • With A->B and B->C cascade mode replication session configured, session A->B and B->C concurrent delete is supported.
        • With A->B and B->C cascade mode replication session configured, when deleting A->B first, the destination mode of the storage object on B is not changed.
    • Pause
      • When pausing NAS server related sessions, only the associated file system session to the same remote system will be paused together with the NAS server session.
      • Other existing replication operations are supported as in earlier OE versions.
    • Resume
      • Only one active destination replica should exist.
      • When resuming the NAS server related sessions, only the associated file system session to the same remote system will be resumed together with the NAS server session. When there are multiple sessions associated with one destination object, it is already acting as a source for some sessions, or it is in destination mode while at least one session is not failed over or switched over.
    Procedure
    1. Access the Replication Session Details screen in one of the following ways:
      • If you know the name of the replication session, go to Protection & Mobility > Replication > Sessions.
      • If you know the name of the storage resource or NAS server associated with the replication session, go to the Replication tab on the Properties window of the relevant storage resource or NAS server.
    2. Perform one of the following actions:
      Note:  On Unity systems running OE version 4.2, the following asynchronous replication actions affect both the NAS server and its associated file systems when run at the NAS server level:
      • Failover
      • Failover-with-sync
      • Failback
      • Pause
      • Resume
      On Unity systems running OE version 4.4, the following synchronous replication actions affect both the NAS server and its associated file systems when run at the NAS server level:
      • Failover
      • Failback
      • Pause
      • Resume
      • Preserve
      Those same replication actions towards a file system, with the exception of Preserve, remain at the file system level. The following asynchronous replication actions affect only the NAS server when run at the NAS server level or are still individual operations toward file system replication sessions:
      • Create
      • Sync (applicable to asynchronous replication only)
      • Delete
      • Modify
      Action Description
      Modify a session
      Select the Edit icon to modify the name and synchronization settings of the session.
      Delete a session
      Select Delete. Deleting a replication session also deletes the internal snapshots used by the session. If the connection between the systems is healthy, the session on the destination system gets automatically deleted when you delete the session on the source system. You can individually delete replication sessions at the source and destination systems, however, this is not recommended unless the connection is down.
      Note:  You cannot delete a replication when a synchronization is in progress.
      Pause and resume a session
      Select Pause or Resume. Pause stops a replication session without deleting the replication session. Resuming a session from the destination system after a failover or failover with sync reverses the direction of the replication. Resume is not available on the destination if the session is not failed over. Changes on the destination system are copied back to the source system at the next RPO interval after a connection is restored.
      Note:  Pausing a replication session while a snapshot is being copied results in stopping the transfer. The destination resource is rolled back to the common base snapshot so that the destination is brought to a consistent state. Resuming a paused session restarts the previously stopped transfer. Replication restores the destination resource to the common base snapshot first, then restarts the snapshot copy by copying the differences between the common base snapshot and the snapshot to be transferred.
      Manually synchronize a session (for asynchronous replication only)
      Select Sync. Changes since the last sync are replicated to the destination system.
      Note:  If an associated synchronous replication session exists between the source site and another destination site when performing this operation, the internal snapshots that are refreshed are replicated on the synchronous replication destination site.
      Fail over a session in an unplanned emergency
      Select Failover. For asynchronous replication, in response to an unplanned emergency scenario in which the source has become unavailable, failover should switch the status of the source and destination storage resources. After the failover operation, the destination object's status becomes read/write, however, the source and destination do not switch roles until a resume operation is run.
      Note:  In this type of failover, any active data transfers are terminated, causing a potential loss of data. If the source site is still available when you perform a failover, the system attempts to change the source object from read/write to read-only.
      For synchronous replication, in response to an emergency/unplanned synchronous replication failover when there is no network connectivity to the source system, use Failover from the destination system without switches, then Resume to restart the sessions on the destination system. This action also reverses the direction from destination to source. Or, instead of doing Resume, you could simply Failback to go back to the source. Also, if an associated asynchronous replication session exists between the source site and another destination site, perform the preserve async operation on the synchronous replication destination site.
      Fail over a session in preparation for a planned downtime (for asynchronous replication only)
      For asynchronous replication, select Failover with Sync. The destination synchronizes with the source storage resource, the replication session is stopped, and the status of the storage resources are switched. After the failover operation, the destination object's status becomes read/write and the source object's status is shown as Restricted Replication Access = Yes.
      Note:  To perform this type of failover, both the source and destination objects of the session must be available.
      For synchronous replication, use Failover from the source system, where sessions remain running and reversed back from the destination to the original source system. After the failover operation, the destination object's status becomes read/write and the source object's status is shown as Restricted Replication Access = Yes. To move back to the original configuration, run another Failover, this time from the destination system, to gracefully fail back to the original source system. A Resume is not required in this scenario because the sessions remain running.
      Fail back a session
      Select Failback. A failback operation switches the status of the storage resources following a failover operation. Once the destination synchronizes with the source again, the source storage resource's status returns to read/write and the destination storage resource's status is shown as Restricted Replication Access = Yes.
      Note:  You can perform this action from the destination system only. Both the source and destination storage resources must be available to perform a successful failback operation.
      Preserve an asynchronous replication session
      Select Preserve. The preserve operation switches the asynchronous replication session related to the synchronous replication session to the active production site after the synchronous replication session (planned or unplanned) has been failed over or failed back.
      Note:  Any modifications to the attributes of the source storage resource are not automatically synchronized over to the destination storage resource. When a failover occurs, ensure that you modify the attributes of the associated destination storage resource to match the attributes of the source storage resource.

    Configure an override network address for file replication

    If you have file replication configured with a destination site on a different physical network, to ensure minimal downtime during a failover, ensure that you modify the destination NAS server properties to include an override address for the network interface.

    Note:   You may still need to manually fail over individual file systems associated with the NAS server.

    If you have configured the source NAS server with LACP or FSN, or both, you must do one of the following:

    • Configure the destination system with the same LACP or FSN configuration. When the LACP/FSN environment is mirrored on the destination system exactly, no further action is required and the destination NAS server will automatically select the LACP/FSN device as part of its configuration.
    • Include an override address for the network interface after first creating the replication session.
    NOTICE  After the replication session has been created and the source NAS server is using an LACP/FSN configuration, you must do the following:
    1. Manually edit the Network settings in the Properties of the NAS server on the destination system.
    2. Select Override address and an interface to use. If you do not do this, a DU after a failover from the source system to the destination system will occur.

    To configure an override address on the destination NAS server:

    Procedure
    1. Under Storage, select File > NAS Servers.
    2. On the Network tab, select the network interface, and click Edit.
    3. On the Edit NAS Server Network Interface screen, select the Override address checkbox, and specify relevant address information.