DX Object Storage Platform: Remote Replication Configuration
Introduction
The Dell
DX Object Storage Platform allows data to be asynchronously replicated from one DX Object
TM
Storage Cluster to another over a standard IP network. Replication is managed by the DX Content
Router (CR) application located on the DX Cluster Services Node (CSN). The CR identifies data to be
replicated based on filter rules defined by the DX Administrator. The rules are compared to meta-data
stored with the objects to determine which objects are to be replicated to a remote cluster. These
rules allow customized data distribution between multiple clusters. Most of the common replication
topologies are achievable through the web-based management console located on the CSN. However,
more complex replication topologies require advanced configuration through configuration files located
on the CSN. The target audience for this document is advanced DX Storage administrators and support
teams. It is meant to provide instructions on advanced configuration of asynchronous remote
replication through these configuration files.
Asynchronous Replication Overview
The CSN provides replication services through the CR application. It also provides a SCSP proxy
interface to the DX Storage Nodes (SN) that allows communication between DX Storage Clusters. This
interface accepts operations from applications and re-directs them to the DX Storage Nodes in the
designated cluster. Asynchronous replication between clusters utilizes the proxy interface to transport
the objects between clusters. The CR application provides two services. The first service is called
Publisher and it is responsible for identifying objects to be replicated based on replication rules set by
DX Administrator and publishing a list of those objects for replication. The second service provided by
CR is called Replicator. The Replicator subscribes to a Publisher, retrieves the list of objects identified
for replication and replicates the objects between clusters. The cluster where data is originated runs
the publisher service. The cluster where the data is to be replicated runs the replicator service.
Figure 1: Asynchronous Replication between Clusters
CSN
Publisher
Proxy
Replication can be configured to support many customized configurations. Replication can be one-way
or two-way. A configuration using one-way replication, from primary to secondary, recognizes a
disaster recovery configuration. Each CSN can run both Publisher and Replicator services enabling two-
way replication for a mirrored configuration. The Publisher service supports multiple channels that
correspond to distinct filter rules, each of which can each be subscribed to by multiple replicators. A
single Replicator can subscribe to multiple Publishers to support a DR roll-up scenario or Replicators
1
CSN
2
Replicator
Proxy
4
3
1. Replicator requests list of objects stored, updated
or deleted from Publisher
2. Replicator receives and stores list on CSN
3. Replicator instructs SN to replicate each object
4. SN initiates GET request for objects
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