Flash storage: Guide to enterprise all-flash storage arrays
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Editor's note: Since this article appeared in May 2014, Violin Memory Inc. has updated its product line with the addition of new all-flash array models and options to add enterprise storage features and management capabilities. In June, the company launched the Concerto 7000 All Flash Array, which combined the company’s 6000 Series storage hardware, updated the controller software and offered options to integrate data services such as synchronous and remote asynchronous replication, stretch metro clusters, and advanced data protection. In July, Violin added four new models of its Windows Flash Array and a pay-as-you-grow pricing option. In August, Violin added inline deduplication and inline compression for file storage with the release of its Concerto 2200 data reduction appliance.
One of the earliest vendors in the all-flash array market, Violin Memory Inc. made performance and low latency its top concerns and concentrated on its proprietary memory module, memory fabric architecture and flash-optimized RAID technology.
The Santa Clara, California-based company has never built storage systems with spinning disks. Its laser focus on solid-state storage has produced technologies to manage the array instead of managing individual solid-state drives (SSDs) and multiple layers of controllers, according to Erik Ottem, the director of product marketing at Violin Memory.
"This provides a more efficient approach, which leads to higher performance, consistently low latency, at a lower cost," Ottem said via email.
VRAID, custom flash modules
Violin is among the minority of flash vendors with proprietary RAID technology, known as vRAID, and custom-built flash modules. The Violin Intelligence Memory Modules (VIMMs) can store up to 1 TB, and they connect to the memory fabric via PCI Express (PCIe).
According to the Violin website, Violin 6000 Series array models range in capacity from 6.5 TB raw (3.5 TB usable) to 70 TB (44 TB usable) in performance from 200,000 IOPS to 1 million IOPS and in bandwidth from 1.5 GBps to 4 GBps. Latency is under 500 microseconds or 250 microseconds, depending on the model. Some products feature higher-endurance single-level cell (SLC) flash, and others have lower-cost multi-level cell (MLC) flash.
The Violin 6264, the Violin 6232, and the Violin 6224 have raw capacities of 70 TB, 35 TB and 26 TB, respectively, and they all use MLC VIMMs. The Violin 6000 Series supports high-performance InfiniBand for storage networking.
But, the Violin 6224, 6232 and 6264 arrays lack some features and capabilities that many all-flash arrays have. Unlike most flash arrays, the Violin product line does not support nondisruptive hardware upgrades and zero block reclaim.
Also, Violin does not support inline deduplication, inline compression, quality of service and replication. However, inline deduplication, inline compression, zero block reclaim, replication, three data center replication and VMware vSphere Metro Storage Cluster (vMSC) certification are in the product plans for this year, according to Ottem.
"Because they were early into the market, they were aimed at the all-out speed category. They didn't have any feature and functionality, nor indeed did they think it was necessary," said Mark Peters, a senior analyst at Milford, Mass.-based Enterprise Strategy Group Inc. "As the market is maturing, that need to have functionality is increasing."
Functionality plus storage management
Violin charges extra for several storage management features. The company's vMOS software package, which incorporates features from Symantec Corp.'s Storage Foundation, includes thin provisioning, snapshots and clones, according to Ottem. Violin also charges a fee for encryption of data at rest, he said.
Violin recently launched a Windows Flash Array (WFA) that it jointly developed with Microsoft. The scale-out, file-based WFA uses Violin's 6264 array with the Windows Server 2012 R2 operating system embedded. The new product is designed to improve the performance of enterprise and cloud workloads that use Microsoft products such as SQL Server databases, SharePoint collaboration software and Hyper-V virtualization applications. Users also gain access to Windows Storage Server 2012 R2 storage features, including thin provisioning, data deduplication, compression, snapshots, mirroring and data-in-flight encryption.
Violin reports less than 10% performance degradation if a controller fails.
The estimated street price for the Violin 6000 Series is around $100,000 for 13 TB of raw (7 TB usable) capacity in the 6212. Violin claims a street price of $4 per GB to $4.50 per GB for its 6264.
Chief use cases for Violin's all-flash arrays include customer relationship management , enterprise resource planning and transaction-oriented applications, databases, online transaction processing, real-time analytics and virtual environments. Violin customers profiled in case studies include Collier County (Florida) Public Schools, Pella Corp., Gilead Sciences Inc. and the University of California at Davis.