Existing data protection technologies are geared towards protecting data and delivering business continuity in the event of a disaster. A vast majority of outages are due to planned events such as hardware or software upgrades, system reconfigurations and expected severe weather events. IT organizations need a new business continuity solution that helps eliminate downtime related to anticipated data center activity. Additionally, such a solution should deliver the flexibility to handle on-demand capability and built-in automation for virtualized data centers and the cloud.

What is Live Volume

Dell Compellent Live Volume is an innovative software feature designed to deliver dynamic business continuity. This feature can help you keep applications online and data accessible during planned or unplanned downtime. Live Volume provides a layer of virtualization that enables a physical server or a virtual machine to share a virtual storage volume between two Compellent SANs in semi-synchronous and synchronous configurations. In this sense, Live Volume acts as a storage hypervisor.

With Live Volume you can create shared volumes live volumes between paired storage arrays, a primary and secondary. Live Volume virtualizes the volume presentation separating it from disk and RAID groups within each storage system. This virtualization enables decoupling of the volume presentation to the host from its physical location on a particular storage array. As a result, promoting the secondary storage array to primary status is transparent to the hosts. The paired SANs can be collocated in the same data center or in two distinct locations. Designating a volume as a live volume eliminates the need for preplanning or predefinition.

Live Volume supports all major virtualized server components, including VMware vSphere, Microsoft Hyper-V, Citrix XenServer and Oracle VM environments.

Dell Compellent Live Volume

Dell Compellent Live Volume

Avoid downtime for planned

outages

Balance workloads on demand

Dynamically deploy resources

across a private cloud

Deploy rich set of replication

topologies

Easily manage multiple sites

Solution Brief

Figure 1. Live Volume: How it works

Automatic storage migration for virtualized environmentsLive Volume automatically detects when a virtual machine moves from one physical server to another and automatically swaps the roles between the primary and secondary systems.

Zero downtime maintenanceLive Volume non-disruptively migrates all volumes from one Storage Center to another, enabling continuous operation for all applications and volumes. This capability lets you promote the remote site as primary, and perform maintenance on the local site without affecting production workload.

Disaster avoidanceIn the event of potential outages due to environmental, like hurricanes, or other causes, any downtime can be eliminated by promoting the remote site to primary status

On-demand load distributionBecause Live Volume virtualizes the storage resources, workloads can be transparently migrated across data centers to achieve better capacity and performance utilization.

Storage Center 6.5: Extending the value proposition

Storage Center (SC) 6.5 enhances the value of Live Volume feature in four key ways.

Synchronous replication supportSC 6.5 introduces a more capable synchronous replication capability between volumes within a Live Volume. If you need higher consistency assurance, leverage the Synchronous High Consistency mode. In this mode, all writes are immediately replicated to the secondary site before a completion is sent to the host. This ensures that primary volume and replica are identical.

You can also leverage the Synchronous High Availability mode to achieve a slightly delayed consistency. In this mode, writes

are journaled if link failure or slowness occurs. Changes are sent to a remote host when the link is reestablished. The new synchronous replication feature delivers the flexibility to deliver the consistency assurances to meet your business needs.

Managed replication to a third nodeSC6.5 introduces a new type of replication that further extends the value proposition of the Live Volume solution. A managed replication is a replication mode where a third DR site can be set up to track the primary volume. Managed replication supports both asynchronous and synchronous replication modes. During a swap role, the managed replication will move its source volume to the swapped storage center transparently. This feature further extends the value of Live Volume by enabling the provisioning of rich replication topologies (Figure 3) to meet advanced business needs.

Flexible replication policy managementEnhancements to SC6.5 extend the industry-leading, easy-to-use Compellent family to replication management. With these enhancements, you can now change the replication relationship between the primary and secondary sites on demand at any time. You can change the replication relationship from asynchronous to synchronous, and vice versa on the fly thereby adjusting the Live Volume deployment to more closely align with the business requirements.

Transparent replication relationship transitionsPrimary and secondary site promotion/demotion operations can easily be performed through the Enterprise Manager GUI. During such operations, managed replications to a third site have to be transitioned carefully. Enhancements in SC6.5 transparently handles these transitions while maintaining the host visible volume identity and preserving the Live Volume relationships.

Figure 2. Types of outages

Live Volume use cases

2015 Dell Inc. SB_Dell_Compellent_Live_Volume_033015

Learn More at Dell.com/Compellent.

Figure 3. Managed replication topologies

Live Volume is a versatile software solution for implementing flexible topologies to meet your business continuity and data recovery needs. Regardless of whether your data center spans a campus, metro or geographically disperse areas, Live Volume combined with managed replication lets you set up topologies

to meet a wide variety of business requirements. Furthermore, the tight integration with Enterprise Manager for easy site promotion coupled with flexible replication policy management helps you meet RPO/RTO objectives in a variety of situations.

Summary