Replication between NetApp Element software and ONTAP overview

Contributors

This content describes how to ensure business continuity on an Element system by using SnapMirror to replicate Snapshot copies of an Element volume to an ONTAP destination. In the event of a disaster at the Element site, you can serve data to clients from the ONTAP system, and then reactivate the Element system when service is restored.

Starting with ONTAP 9.4, you can replicate Snapshot copies of a LUN created on an ONTAP node back to an Element system. You might have created a LUN during an outage at the Element site, or you might be using a LUN to migrate data from ONTAP to Element software.

You should use this content if you want to work with Element to ONTAP backup in the following way:

  • You want to use best practices, not explore every available option.

  • You do not want to read a lot of conceptual background.

  • You want to use the ONTAP command-line interface (CLI), not ONTAP System Manager or an automated scripting tool.

  • You are using iSCSI to serve data to clients.

If you require additional configuration or conceptual information, see the following documentation:

About replication between Element and ONTAP

Starting with ONTAP 9.3, you can use SnapMirror to replicate Snapshot copies of an Element volume to an ONTAP destination. In the event of a disaster at the Element site, you can serve data to clients from the ONTAP system, then reactivate the Element source volume when service is restored.

Starting with ONTAP 9.4, you can replicate Snapshot copies of a LUN created on an ONTAP node back to an Element system. You might have created a LUN during an outage at the Element site, or you might be using a LUN to migrate data from ONTAP to Element software.

Types of data protection relationship

SnapMirror offers two types of data protection relationship. For each type, SnapMirror creates a Snapshot copy of the Element source volume before initializing or updating the relationship:

  • In a disaster recovery (DR) data protection relationship, the destination volume contains only the Snapshot copy created by SnapMirror, from which you can continue to serve data in the event of a catastrophe at the primary site.

  • In a long-term retention data protection relationship, the destination volume contains point-in-time Snapshot copies created by Element software, as well as the Snapshot copy created by SnapMirror. You might want to retain monthly Snapshot copies created over a 20-year span, for example.

Default policies

The first time you invoke SnapMirror, it performs a baseline transfer from the source volume to the destination volume. The SnapMirror policy defines the contents of the baseline and any updates.

You can use a default or custom policy when you create a data protection relationship. The policy type determines which Snapshot copies to include and how many copies to retain.

The table below shows the default policies. Use the MirrorLatest policy to create a traditional DR relationship. Use the MirrorAndVault or Unified7year policy to create a unified replication relationship, in which DR and long-term retention are configured on the same destination volume.

Policy Policy Type Update behavior

MirrorLatest

async-mirror

Transfer the Snapshot copy created by SnapMirror.

MirrorAndVault

mirror-vault

Transfer the Snapshot copy created by SnapMirror and any less recent Snapshot copies made since the last update, provided they have SnapMirror labels “daily” or “weekly”.

Unified7year

mirror-vault

Transfer the Snapshot copy created by SnapMirror and any less recent Snapshot copies made since the last update, provided they have SnapMirror labels “daily”, “weekly”, or “monthly”.

Note

For complete background information on SnapMirror policies, including guidance on which policy to use, see Data Protection.

Understanding SnapMirror labels

Every policy with the “mirror-vault” policy type must have a rule that specifies which Snapshot copies to replicate. The rule “daily”, for example, indicates that only Snapshot copies assigned the SnapMirror label “daily” should be replicated. You assign the SnapMirror label when you configure Element Snapshot copies.

Replication from an Element source cluster to an ONTAP destination cluster

You can use SnapMirror to replicate Snapshot copies of an Element volume to an ONTAP destination system. In the event of a disaster at the Element site, you can serve data to clients from the ONTAP system, then reactivate the Element source volume when service is restored.

An Element volume is roughly equivalent to an ONTAP LUN. SnapMirror creates a LUN with the name of the Element volume when a data protection relationship between Element software and ONTAP is initialized. SnapMirror replicates data to an existing LUN if the LUN meets the requirements for Element to ONTAP replication.

Replication rules are as follows:

  • An ONTAP volume can contain data from one Element volume only.

  • You cannot replicate data from an ONTAP volume to multiple Element volumes.

Replication from an ONTAP source cluster to an Element destination cluster

Starting with ONTAP 9.4, you can replicate Snapshot copies of a LUN created on an ONTAP system back to an Element volume:

  • If a SnapMirror relationship already exists between an Element source and an ONTAP destination, a LUN created while you are serving data from the destination is automatically replicated when the source is reactivated.

  • Otherwise, you must create and initialize a SnapMirror relationship between the ONTAP source cluster and the Element destination cluster.

Replication rules are as follows:

  • The replication relationship must have a policy of type “async-mirror”.

    Policies of type “mirror-vault” are not supported.

  • Only iSCSI LUNs are supported.

  • You cannot replicate more than one LUN from an ONTAP volume to an Element volume.

  • You cannot replicate a LUN from an ONTAP volume to multiple Element volumes.

Prerequisites

You must have completed the following tasks before configuring a data protection relationship between Element and ONTAP:

  • The Element cluster must be running NetApp Element software version 10.1 or later.

  • The ONTAP cluster must be running ONTAP 9.3 or later.

  • SnapMirror must have been licensed on the ONTAP cluster.

  • You must have configured volumes on the Element and ONTAP clusters that are large enough to handle anticipated data transfers.

  • If you are using the “mirror-vault” policy type, a SnapMirror label must have been configured for the Element Snapshot copies to be replicated.

    Note

    You can perform this task in the Element software web UI only. For more information, see the NetApp Element software documentation

  • You must have ensured that port 5010 is available.

  • If you foresee that you might need to move a destination volume, you must have ensured that full-mesh connectivity exists between the source and destination. Every node on the Element source cluster must be able to communicate with every node on the ONTAP destination cluster.

Support details

The following table shows support details for Element to ONTAP backup.

Resource or feature Support details

SnapMirror

  • The SnapMirror restore feature is not supported.

  • The MirrorAllSnapshots and XDPDefault policies are not supported.

  • The “vault” policy type is not supported.

  • The system-defined rule “all_source_snapshots” is not supported.

  • The “mirror-vault” policy type is supported only for replication from Element software to ONTAP. Use “async-mirror” for replication from ONTAP to Element software.

  • The -schedule and -prefix options for snapmirror policy add-rule are not supported.

  • The -preserve and -quick-resync options for snapmirror resync are not supported.

  • Storage efficiency is not preserved.

  • Fan-out and cascade data protection deployments are not supported.

ONTAP

  • ONTAP Select is supported starting with ONTAP 9.4 and Element 10.3.

  • Cloud Volumes ONTAP is supported starting with ONTAP 9.5 and Element 11.0.

Element

  • Volume size limit is 8 TiB.

  • Volume block size must be 512 bytes. A 4K byte block size is not supported.

  • Volume size must be a multiple of 1 MiB.

  • Volume attributes are not preserved.

  • Maximum number of Snapshot copies to be replicated is 30.

Network

  • A single TCP connection is allowed per transfer.

  • The Element node must be specified as an IP address. DNS hostname lookup is not supported.

  • IPspaces are not supported.

SnapLock

SnapLock volumes are not supported.

FlexGroup

FlexGroup volumes are not supported.

SVM DR

ONTAP volumes in an SVM DR configuration are not supported.

MetroCluster

ONTAP volumes in a MetroCluster configuration are not supported.