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Technical White PaperDell EMC Unity: Replication TechnologiesA Detailed ReviewAbstractThis white paper explains the replication solutions for Dell EMC Unity systems.This paper outlines the native and non-native options available for replicatingdata. It also includes information about managing replication, and the benefitsthat replication provides. Native file synchronous replication is coveredseparately in the Dell EMC Unity: MetroSync white paper which can be found onDell EMC Online Support.June 2021Dell EMC Unity: Replication Technologies H15088.7

RevisionsRevisionsDateDescriptionMay 2016Initial release – Unity OE 4.0December 2016Updated for Unity OE 4.1July 2017Updated for Unity OE 4.2March 2018Updated for Unity OE 4.3August 2018Updated for Unity OE 4.4January 2019Updated for Unity OE 4.5June 2019Updated for Unity OE 5.0January 2021Metro node updatesJune 2021Template and format updates. Updated for Unity OE 5.1.AcknowledgmentsAuthor: Ryan PoulinThe information in this publication is provided “as is.” Dell Inc. makes no representations or warranties of any kind with respect to the information in thispublication, and specifically disclaims implied warranties of merchantability or fitness for a particular purpose.Use, copying, and distribution of any software described in this publication requires an applicable software license.This document may contain certain words that are not consistent with Dell's current language guidelines. Dell plans to update the document oversubsequent future releases to revise these words accordingly.This document may contain language from third party content that is not under Dell's control and is not consistent with Dell's current guidelines for Dell'sown content. When such third party content is updated by the relevant third parties, this document will be revised accordingly.Copyright 2016-2021 Dell Inc. or its subsidiaries. All Rights Reserved. Dell Technologies, Dell, EMC, Dell EMC and other trademarks are trademarksof Dell Inc. or its subsidiaries. Other trademarks may be trademarks of their respective owners. [6/21/2021] [Technical White Paper] [H15088.7]Dell EMC Unity: Replication Technologies H15088.7

Table of contentsTable of contentsRevisions.2Acknowledgments .2Table of contents .3Executive summary .6Audience .61Introduction .71.12Terminology .7Native synchronous block replication .102.1Licensing .102.2Theory of operation .102.2.1 Synchronous replication interfaces.102.2.2 Synchronous Replication Management Ports .112.2.3 Replication Connections .122.2.4 Replication Sessions .122.2.5 Storage Resources .132.2.6 Replication Roles .132.3Replication Operations .142.3.1 Pause and Resume .142.3.2 Failover and Failback .152.3.3 Delete .152.4Data Protection Mechanisms .162.4.1 Fracture Log .162.4.2 Write Intent Log .162.5Supported Replication Configurations .172.6Unisphere Management .182.6.1 Configuring Replication .182.6.2 Synchronous Replication Management Ports .182.6.3 Creating a Replication Connection .202.6.4 Creating a Replication Session .212.6.5 Viewing the Replication Sessions .262.73System Maximums .27Native Asynchronous Replication.283.1Licensing .283.2Theory of Operation .283.2.1 Replication Interfaces .28Dell EMC Unity: Replication Technologies H15088.7

Table of contents3.2.2 Replication Connections .303.2.3 Replication Sessions .353.2.4 Asynchronous Replication Internal Snapshots .363.2.5 Storage Resources .373.2.6 Replication Roles .383.3Replication Operations .393.3.1 Pause and Resume .393.3.2 Sync .403.3.3 Failover with Sync, Failover, and Failback .403.3.4 Delete .413.3.5 Group Operations .423.4Supported Replication Configurations .423.4.1 Local Replication .423.4.2 Remote Replication .433.4.3 Advanced File Remote Replication .453.4.4 MetroSync .493.5Snapshot Replication .493.6Unisphere Management .503.6.1 Configuring Replication .513.6.2 Creating Replication Interfaces .513.6.3 Creating a Replication Connection .523.6.4 Creating a Replication Session .543.6.5 Restore from a replicated snapshot.643.6.6 Override network address for file replication .643.6.7 Enable NDMP on NAS Server .653.6.8 Viewing the Replication Sessions.663.7System Maximums .674Proxy NAS Servers .685Interoperability .695.1Snapshots .695.1.1 Create replication session .695.1.2 Failback/Resume after unplanned failover .7365.2File Import .745.3Data Reduction .745.4Dynamic Pools .75Upgrades .76Dell EMC Unity: Replication Technologies H15088.7

Table of contents7RecoverPoint with Dell EMC Unity .778Metro node .789Conclusion .79ATechnical support and resources .80A.1Related resources.80BAppendix: Replication Maximums .81CAppendix: Replication Support Across Platforms.82Dell EMC Unity: Replication Technologies H15088.7

Executive summaryExecutive summaryData is often one of the most valuable assets to an organization. It is being accessed constantly by thevarious applications, users, and sometimes directly by customers of the organization. This makes data acrucial part of the day to day operations of an organization. Outages can happen at any time, and can berestricted to a single system, or an entire data center or location. Whether they are planned outages, such asregular maintenance, or unplanned such as a power outage, ensuring that data critical to the organization isavailable at all times is a top priority. A business continuity plan for critical data is suggested to prevent costlyoutages. To protect against the different scenarios, an organization should plan and implement a dataprotection strategy. A data replication solution can ensure business continuity, high availability, and dataprotection. Dell EMC Unity provides native and non-native solutions that will help you protect your data andmeet the goals of your business for both data availability and protection.Dell EMC Unity systems provide synchronous and asynchronous replication solutions which allow you toreplicate data locally within the same system, or to other systems, whether they are located at the same siteor a remote facility. Having remote replicas of data protects you against outages on the main system andallows you to recover quickly and easily on a destination system with minimal to no data loss depending onthe replication method selected.This white paper describes the following replication technologies for Dell EMC Unity: Native Synchronous Block ReplicationNative Asynchronous Block and File ReplicationDell EMC RecoverPoint Dell EMC Unity also supports native file synchronous replication. For information about native filesynchronous replication and MetroSync Manager, reference the Dell EMC Unity: MetroSync white paper onDell EMC Online Support.Synchronous Block Replication, Asynchronous Block and File Replication, and Manual Replication can easilybe configured and managed in Unisphere, Unisphere CLI, or REST API. Unisphere is a simple and intuitiveHTML5 web-based interface which not only allows users to configure and manage their replication setup, butalso provides a visual representation of the configuration.Dell EMC RecoverPoint is an appliance-based product providing an alternative solution for Block Replicationfor Dell EMC Unity systems. Configuring RecoverPoint protection is done through the intuitive Unisphere forRecoverPoint interface. RecoverPoint allows for the recovery of data for any point-in-time and replicate toother supported Dell EMC storage systems.AudienceThis white paper is intended for Dell EMC customers, partners, and employees who are considering the useof Native Synchronous Block Replication, Native Asynchronous Block and File Replication, or RecoverPointfor the Dell EMC Unity family of storage systems. It assumes familiarity with Dell EMC Unity and Dell EMC’smanagement software.Dell EMC Unity: Replication Technologies H15088.7

Introduction1IntroductionTo protect against outages which can interrupt data availability, it is crucial to have a redundant copy of data.To protect against a storage system outage, you can use replication to create a copy of data on a remotesystem. Replication is a software feature which synchronizes data to a remote system within the same site ora different location. Replicating data helps to provide data redundancy, and safeguards against storagesystem failures at the main production site. Having a remote Disaster Recovery (DR) site protects againstsystem and site-wide outages and provides a remote location to resume production and minimize downtimedue to a disaster. For Dell EMC Unity, the platform offers many replication solutions to easily meet disasterrecovery needs in customer environments.Synchronous replication is a data protection solution which ensures each block of data written to a storageresource is first saved locally and to a remote image before the write is acknowledged to the host. Thisensures that in the event of a disaster, there is zero data loss. In synchronous replication solutions, there arealso trade-offs. As each write needs to be saved locally and remotely, added response time occurs duringeach transaction. This response time increases as distance increases between remote images. Synchronousreplication has a distance limitation based on latency between systems. This limitation is generally 60 miles or100 km between sites. It is recommended to ensure the latency of the link between the local and remotesystem is less than 10 milliseconds.Asynchronous replication is primarily used to replicate data over long distances, but also can be used toreplicate storage resources between Pools within the same system. Asynchronous replication does notimpact host I/O latency as host writes are acknowledged once they are saved to the local storage resource.Because write operations are not immediately replicated to a destination resource, all writes are tracked onthe source. This data will be replicated during the next synchronization. Asynchronous replication introducesthe concept of a Recovery Point Objective (RPO). RPO is the acceptable amount of data, measured in unitsof time, which may be lost due to a failure. This delta of time also affects the amount of data which needs tobe replicated during the next synchronization, and the amount of potential data loss if a disaster scenariowere to occur.Dell EMC Unity’s synchronous and asynchronous replication features can easily be configured usingUnisphere, Unisphere CLI, or REST API. Dell EMC Unity also supports manual replication, which does notautomatically update a destination image with changes on the source. Manual replication will be discussedwith asynchronous replication. RecoverPoint also supports block replication for Dell EMC Unity and will bediscussed later in this paper. RecoverPoint uses physical or virtual appliances to replicate data betweensystems and is configured using the Unisphere for RecoverPoint user interface.The Dell EMC Unity File synchronous replication feature and MetroSync Manager is covered in the Dell EMCUnity: MetroSync white paper, which can be found on Dell EMC Online Support.1.1TerminologyAsynchronous Replication: A replication method which allows you to replicate data over long distances andmaintain a replica at a destination site. Updates to the destination image can be issued manually, orautomatically based on a customizable Recovery Point Objective (RPO).Bandwidth: The amount of data, represented in MB/s, which can be transferred in a given period of time.Common Base: A pair of Unified Snapshots taken on a replication source and destination storage resourcewhich have the same point-in-time image.Dell EMC Unity: Replication Technologies H15088.7

IntroductionConsistency Group (Dell EMC Unity): A storage instance which contains one or more LUNs within astorage system. Consistency groups help organize the storage allocated for a particular host or hosts.Consistency Group (RecoverPoint): In RecoverPoint, a consistency group is a user-defined group of LUNsto be replicated. A consistency group needs to be created in RecoverPoint as a part of the workflow toconfigure replication. This consistency group containing Dell EMC Unity LUNs can be replicated locally orremotely. RecoverPoint consistency groups are synonymous with Dell EMC Unity consistency groups.Destination Storage Resource: A storage resource that is used for disaster recovery in a replicationsession. This is also known as a target image.Fracture Log: A bitmap held in persistent memory on each storage processor which indicates which physicalareas of a source resource participating in a synchronous replication session have been updated sincecommunication was interrupted (fracture).Internal Snapshot (Replication Snapshot): Unified Snapshots created by the system which are part of anasynchronous replication session. These snapshots can be viewed in Unisphere, but user operations are notpermitted. Each asynchronous replication session uses two internal snapshots taken on the source anddestination storage resources.Journal Volume: In RecoverPoint, a journal volume is a LUN designated to hold data associated withprevious points-in-time. The journal is used to allow RecoverPoint to roll back data to any point-in-time.Journal volumes must be configured for each copy of a consistency group, including the production copy.LUN: A block-based storage resource which a user provisions. It represents a SCSI logical unit.RecoverPoint: An appliance-based disaster recovery solution that replicates synchronously orasynchronously and enables recovery to any point-in-time.RecoverPoint Appliance (RPA): An industry-standard server platform that runs RecoverPoint software andmanages all aspects of data protection for a consistency group. RPAs are clustered at each site in aRecoverPoint system for high availability and load balancing. Virtual machines running RecoverPointsoftware, or vRPAs, are also supported as an alternative to physical appliances.Recovery Point Objective (RPO): The acceptable amount of data, measured in units of time, which may belost due to a failure. For example, if a storage resource has an RPO of 1 hour, any data written to the storageresource within the most recent hour may be lost when the replication session is failed over to the destinationstorage resource.Recovery Time Objective (RTO): The duration of time in which a business process must be restored after adisaster. For example, an RTO of 1 hour requires access to the data be restored within 1 hour after a disasteris encountered.Replication Session: A relationship configured between two storage resources of the same type, on thesame or different systems, to automatically or manually synchronize the data from one resource to another.Snapshot: A snapshot, also called a Unified Snapshot, is a point-in-time view of a storage resource. When asnapshot is taken, the snapshot is an exact copy of the source storage resource and shares all blocks of datawith it. As data changes on the source, new blocks are allocated and written to. Unified Snapshot technologycan be used to take a snapshot of a Block or File storage resource.Storage Resource: The top-level object a user can provision, associated with a specific quantity of storage.All host access and data protection activities are performed at this level. In this document, storage resourceDell EMC Unity: Replication Technologies H15088.7

Introductionrefers specifically to those which support replication: LUNs, consistency groups, NAS Servers, file systems,and VMware VMFS and NFS Datastores.Synchronous Replication: A replication mode in which the host initiates a write to the system at a local siteand the data must be successfully stored in both local and remote sites before an acknowledgment is sentback to the host.Thin Clone: A thin clone is a Read/Write copy of a Thin Block storage resource (LUN, consistency group, orVMware VMFS datastore) that shares blocks with the parent resource.Unisphere: A web-based Dell EMC management interface for creating storage resources and configuringand scheduling protection of stored data on a Dell EMC Unity system. Unisphere can be used for allmanagement of Dell EMC Unity native replication.Unisphere for RecoverPoint: A web-based interface for managing RecoverPoint replication. It serves as asingle pane of glass for replicating storage resources of multiple storage systems configured to useRecoverPoint. Consistency groups are created, replicated, and recovered through this interface.User Snapshot: A snapshot created manually by the user or by a schedule. This is different than an internalsnapshot, which is taken automatically by the system with asynchronous replication.Write Intent Log: A record stored in persistent memory on the Dell EMC Unity storage system which tracksin-flight writes between systems participating in synchronous replication.Dell EMC Unity: Replication Technologies H15088.7

Native synchronous block replication2Native synchronous block replicationThis section will discuss the native synchronous block replication feature found on Dell EMC Unity systems.This feature allows users to create synchronous replication sessions for Block storage resources betweensupported systems. All configuration and management operations in this section will be demonstrated inUnisphere, though Unisphere CLI and REST API may also be used. The following sections of this paper willdiscuss: The licensing requirements for the native synchronous block replication featureHow the native synchronous replication feature worksThe configurations supported for synchronous replicationUnisphere configuration and managementSynchronous block replication using RecoverPoint will be discussed in the RecoverPoint with Dell EMC Unitysection.2.1LicensingFor Dell EMC Unity, synchronous block replication is only supported on physical deployments. The supportedsystems include the All Flash models, and the Hybrid models. For Dell EMC Unity All Flash and Hybridsystems, Synchronous Block Replication license comes included at no additional cost.2.2Theory of operationNative synchronous block replication is consisted of a number of physical and software components. Each ofthese components will be discussed in the following sections. To fully configure synchronous replication, youmust complete each of following: Configure FC connectivity for synchronous replication data transferConfigure network interfaces on the synchronous replication management ports for replicationcommand communicationConfigure a replication connection between systemsConfigure replication sessions between systemsAlso discussed in this section will be the various storage resources which support synchronous replication,and the different replication modes and roles for synchronous replication. The following sections detail thefunctions, requirements, and interactions of these components. The configuration and management of thesecomponents in Unisphere will be discussed in the Unisphere Management subsection.2.2.1Synchronous replication interfacesNative synchronous block replication is performed over the first Fibre Channel (FC) port configured on thesystem. Older model Dell EMC Unity physical systems include two onboard Converged Network Adapter(CNA) ports which can be configured with either 16 Gb FC SFPs, 10 Gb Optical SFPs, or be used withTwinax cables. When configured as Fibre Channel, the lowest numbered port will be used for thesynchronous replication interface on each SP. When the CNA is not configured for Fibre Channel, a 16 GbFibre Channel I/O m

Revisions Dell EMC Unity: Replication Technologies H15088.7 Revisions Date Description May 2016 Initial rele