DataCore™ Virtual SAN introduces the next evolution in Software-defined Storage (SDS) by creating high-performance and highly-available shared storage pools using the disks and flash storage in your servers. It addresses the requirements for fast and reliable access to storage across a cluster of servers at remote sites as well as in high-performance applications.

DataCore Virtual SAN virtualizes the local storage on two or more physical x86-64 servers. It can leverage any combination of magnetic disks (SAS, SATA) and optionally flash, to provide persistent storage services as close to the application as possible without having to go out over the wire (network or fabric). Virtual disks provisioned from DataCore Virtual SAN can also be shared across the cluster to support the dynamic migration and failover of applications between hosts.

DataCore Virtual SAN addresses the challenges that exist today within many IT organizations such as single points of failure, poor application performance (particularly within virtualized environments), low storage efficiency and utilization, and high infrastructure costs.

Let’s explore how DataCore Virtual SAN addresses each of these challenges with a proven, 10th generation software-defined storage solution, purpose-built for maximizing storage resources across the enterprise.

DataCore Virtual SAN Technical Whitepaper A Deep Dive into Converged Storage

Virtual SAN Benefits

Only 2 servers needed for High-Availability

RAM for I/O Acceleration

Flash is Optional

50M IOPS, 32PB with 32 Host Cluster

Works with all major Hypervisors

Integrate Converged, SAN, and Cloud Storage

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Synchronous MirroringThe availability of business-critical data is extremely important for your organization. DataCore Virtual SAN provides protection against catastrophic events; outages that fault-tolerance measures alone cannot adequately protect against. Synchronous mirroring provides data-level redundancy to maximize data availability and keep applications running without interruption.

DataCore Virtual SAN accomplishes high-availability within the cluster by synchronously mirroring every data block between two fully active cluster nodes, where others may require three or more hosts to accomplish that same capability. The two nodes maintain redundant copies of the data ensuring that even if one cluster node becomes inoperable, the applications will not experience any interruption, and the data is always available.

Below is a diagram that outlines the order of operations that occurs during synchronous mirroring:

Synchronous mirroring also plays a role in providing redundant write cache. When running in a mirrored configuration, a high-speed write cache is enabled. Writes are only confirmed when both nodes acknowledge they have received the data. If a partner node becomes unavailable due to maintenance for example, then write data is still safe and destaged to persistent storage. Unlike other solutions, where performance degrades significantly when a loss of redundancy occurs, DataCore Virtual SAN read cache and write-coalescing functions are still enabled, providing read acceleration and optimized destaging operations.

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1. Inbound write I/O received from Host at Site A

2. Inbound write I/O committed to high-speed RAM cache on SSV-1

3. Inbound write I/O transferred to SSV-2

4. Inbound write I/O committed to high-speed RAM cache on SSV-2

5. Acknowledgement of write I/O receipt from SSV-2 to SSV-1

6. Acknowledgement of write I/O receipt from SSV-1 to Host at Site A

7. Inbound write I/O is destaged from cache to internal storage

Challenge #1: Elimate Single Points of Failure and DowntimeData availability involves achieving data redundancy and maintaining accessibility even in the event of a catastrophic failure within the storage architecture due to hardware malfunctions, site failures, regional disasters, and user errors. DataCore Virtual SAN provides full data redundancy and eliminates interruptions using synchronous mirroring.

Synchronous Mirroring Order of Operations

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High-speed Caching

The first feature responsible for storage acceleration within the cluster is high-speed cache. Many other solutions today require the use of flash as a caching device. DataCore Virtual SAN leverages RAM as high-speed cache, along with the hosts’ local processors and I/O resources, to execute sophisticated multi-threaded read and write caching algorithms across all storage devices under its management.

High-speed caching drastically improves overall application performance by pre-fetching and storing the most frequently accessed data in local memory, optimizing data transfers to storage through write coalescing (sequential ordering), and acting as a speed-matching write buffer to alleviate inbound channel congestion. Up to 1 Terabyte (TB) of RAM can be reserved per node forming cluster-wide mega-caches.

Using RAM as a high-speed cache offers several unique advantages since RAM is many orders of magnitude faster than flash technologies. RAM is mirrored for inbound write data, is not impacted by wearing or write-amplification effects like flash, and resides closest to the CPU to minimize latency. It is the fastest storage component in the storage architecture, helping to deliver up to 10X performance boost to applications and freeing up hosts to perform other tasks. It also extends the life of traditional magnetic storage components by minimizing the stress experienced from disk thrashing due to I/O intensive workloads.

While flash is inadequate to perform high-speed caching functions, it can be used as persistent storage within a disk pool and to accelerate frequently accessed data provided via the auto-tiering feature. In this manner, its performance and capacity attributes contribute to the system, as opposed to other solutions which only use flash for a system-wide cache.

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Challenge #2: Improve Application PerformanceToday’s demanding applications, especially within virtualized environments, require high performance from storage to keep up with the rate of data acquisition and unpredictable demands of enterprise workloads. DataCore Virtual SAN provides substantial storage acceleration through two primary features: high-speed caching & automated storage tiering.

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Automated Storage TieringThe second feature responsible for storage acceleration within the cluster is automated storage tiering. Automated storage tiering is designed to move data to higher performing storage tiers based on access frequency. When a high-capacity disk is combined with high-speed storage devices such as flash, it yields markedly better application performance at scale.

Unlike other auto-tiering solutions, which tend to be manual or at best scheduled, DataCore Virtual SAN auto-tiering is a fully-automated real-time mechanism. In the background, it analyzes data block requests and chooses the best placement for your data based on access frequency. Both read and write access patterns can influence the auto-tiering mechanism. Also, auto-tiering policies apply on a per- virtual disk basis granting you granular control over optimizations.

Automated storage tiering provides seamless integration of high-speed storage devices, such as optional flash, with different types of magnetic high-capacity devices (such as SAS and SATA drives). A very compelling reason to use auto-tiering is that only a small amount of flash disk is needed to significantly improve application performance and user experience. Adding just a small amount of flash, typically 8-10% of the total storage pool capacity, yields significant performance enhancements.

DataCore Virtual SAN supports many different tiers of storage technology including cloud storage for infrequently accessed, long-term archival data. As more advanced technologies become available, tiers can be modified or added as necessary to maintain performance service levels.

CPU-Storage ProximityAn important characteristic of DataCore Virtual SAN is that high-speed storage services reside as close to the CPU and applications as possible. This type of architecture reduces the number of components and the distance involved in accessing the data. The result is greatly improved application responsiveness and performance.

In general, RAM is the fastest and closest component to the CPU. It is followed by PCIe flash, storage connected via an internal controller, and finally external storage arrays. By minimizing the number of components that must be traversed to access the data, context switching is minimized, and therefore latency. DataCore Virtual SAN uses RAM as high-speed cache, providing the closest proximity to storage services.

The locality of persistent storage is also an important design consideration. As shown above, latency increases the further the data resides from the CPU. Leveraging PCIe flash with internal disks eliminates the inherent latency attributed with traversing the external network or fabric. This combined with auto-tiering provides a highly-optimized, high-performance storage solution.

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DataCore Virtual SAN uses thin provisioning which allocates storage only when data is written resulting in an increase of storage utilization to as high as 95%. Thin provisioning is accomplished by presenting a standard storage volume which appears to have been fully provisioned and allocated, when in fact nothing has been allocated. Only when the application writes data are the storage blocks granularly allocated for that particular volume. Conversely, automatic zero-block reclamation constantly analyzes the thin provisioned storage blocks looking for those which have been zeroed out due to data removal by the host.

But what about scalability? Expanding storage resources separately from compute resources is another important advantage of DataCore Virtual SAN over other solutions.

To scale storage, you can choose to:

• Expand capacity by adding more internal storage to existing hosts (scale up)

• Add hosts which contribute more storage (scale out)

• Tapping into external storage on a central SAN and/or cloud storage

• Supplement on-premise storage with cloud storage

Note: Other alternatives confine you to options A and B. They do not permit access to capacity in your SAN (option C) or cloud storage (option D)

To scale out processing power, you may:

• Expand compute resources by adding more hosts without data storage

• Expand compute and storage resources concurrently by adding hosts

• Substitute faster hosts

In all cases, you have full control over how best to scale of and storage resources independently within the cluster.

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Challenge #3: Increase Efficiency and ScalabilityDataCore Virtual SAN RAM automatically improves storage efficiency and utilization through thin provisioning. With storage systems that do not utilize thin provisioning, storage is allocated on a per-volume per-application basis. This results in much of the available storage being wasted since the unused space on each volume is inaccessible by other applications. The industry average storage utilization without thin provisioning is around 35%.

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Ultimate Storage Convergence:As noted earlier, the DataCore Virtual SAN can also take advantage of existing central SANs and cloud storage for additional capacity without having to add extra components to the cluster. Unify all your storage under DataCore control and manage it all from the same console.

This gives you the best of both worlds. The fastest storage is right next to your applications directly on the host, yet you can access more capacity or a different class of storage from the central SAN or cloud storage as needs arise. The auto-tiering software can do this for you without manual intervention. No other product offer this capability!

You may also choose to mirror certain virtual disks between your hosts and the central SAN / cloud storage, rather than between hosts. Or, replicate between a DataCore Virtual SAN at remote locations to a central DataCore SAN at the main data center or to cloud storage. The point is that applications clusters don’t need to become isolated as others would have you do. They can be fully integrated into the broader storage infrastructure to harness all the assets available to you.

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Deploying a Converged, Flexible ArchitectureConsolidate your architecture to one-third of its traditional size and introduce your choice of storage components necessary to deliver the performance and capacity your applications require. And as conditions change over time, deploy additional storage components to meet the new resource demands, all without interruption or risk to your data.

Achieving High Performance at Lower Cost The use of low cost RAM as high-speed cache gives you a significant performance-cost advantage. Additionally, over time it also reduces the number of device failures since the backend storage systems are not being overwhelmed with constant high I/O activity. The use of RAM along with less stress on storage components results in a significantly lower total operating cost. And unlike other solutions, the use of flash is optional with DataCore Virtual SAN.

Integrate DataCore Virtual SAN with Central SAN / Cloud Storage Whether you have an existing central SAN / Cloud Storage architecture or you need to expand to one in the future, DataCore Virtual SAN seamlessly unifies both architectures and provides a single pane of glass management interface for the entire environment.

Only Two Nodes Needed To Start DataCore Virtual SAN only requires two nodes to get started and can be incremented one node at a time. Other solutions need three or more nodes to be fully functional.

Cross Hypervisor Support DataCore Virtual SAN supports all industry hypervisors such as vSphere, Hyper-V, XenServer, and KVM. Different hypervisors offer different advantages. It may be optimal to deploy one type of hypervisor for critical enterprise-class workloads such as line-of-business applications or databases and another type for non-critical workloads such as virtual desktops. Whether deployed at headquarters, at a branch office, or both, DataCore Virtual SAN will provide the same enterprise class storage and management services.

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Challenge #4: Reduce Infrastructure CostsDataCore Virtual SAN significantly lowers your TCO by:

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Applicable Use CasesDataCore Virtual SAN opens up many new possibilities within the infrastructure. Below are some of the most common use cases:

DatabasesDatabase applications such as SQL, Oracle, and SAP run best in a low latency high-throughput storage environment. DataCore Virtual SAN delivers low latency storage access by providing storage services as close to the application as possible. Additionally, high-speed caching functions leverage RAM, which is the fastest storage component in the system. The result is significantly improved database application performance.

Virtual Desktop (VDI) Deployments Run more virtual desktops (both VMware Horizon and Citrix XenDesktop) on each hypervisor host and scale them out across more servers without the complexity or expense of an external SAN.

Compact Server Clusters at Remote Sites and Branch Offices Put the internal storage capacity of your application servers to work as a shared resource while protecting your data against outages. Industries such as retail, hospitality, manufacturing, and healthcare benefit greatly from converged highly-available architectures.

Summary of BenefitsDataCore Virtual SAN provides many benefits to your infrastructure such as:

Highest PerformanceHighest storage performance through the use of high-speed RAM as cache.

Achieve end-to-end hardware independenceJust as server virtualization decouples ‘computing’ from the server hardware, storage virtualization decouples the ‘data’ from the storage hardware, resulting in complete infrastructure-wide flexibility.

Low upfront capital expenditure Add resources as performance and capacity demands increase.

ConclusionDataCore Virtual SAN is the next evolution in software-defined storage which provides high-performance and highly-available shared storage pools using the disks and flash storage in your application servers; and if necessary, integrate external storage.

DataCore Virtual SAN will significantly improve application performance and responsiveness, eliminate single points of failure, increase storage efficiency and utilization, and lower infrastructure costs. It provides complete storage flexibility, leveraging any make and model of storage device, all while providing blazing performance and the most advanced forms of data protection. And as conditions change over time, expand and adapt to fulfill new demands without interrupting access to your data.

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For additional information, please visit www.datacore.com or email info@datacore.com© 2014 DataCore Software Corporation. All Rights Reserved. DataCore, the DataCore logo and SANsymphony are trademarks or registered trademarks of DataCore Software Corporation. All other products, services and company names mentioned herein may be trademarks of their respective owners.

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DataCore SoftwareDataCore is a leader in software-defined storage. The company’s storage virtualization software empowers organizations to seamlessly manage and scale their data storage architectures, delivering massive performance gains at a fraction of the cost of solutions offered by legacy storage hardware vendors. Backed by 10,000 customer sites around the world, DataCore’s adaptive and self-learning and healing technology takes the pain out of manual processes and helps deliver on the promise of the new software-defined data center through its hardware agnostic architecture. For more information go to www.datacore.com