DELL EMC Glossary


Flash storage is any storage repository that uses flash memory. Flash memory comes in many forms, and you probably use flash storage every day. From a single flash chip on a simple circuit board, to circuit boards in your phone or MP3 player, to fully integrated “enterprise flash storage devices” where multiple chips are used in place of a spinning disk, flash storage is everywhere!

What is flash storage SSD?

A “solid state drive” or EFD “enterprise flash drive” is a fully integrated circuit board where many flash chips are engineered to represent a single flash storage device. Primarily used to replace traditional spinning disk, SSDs are used in MP3 players, laptops, servers, and enterprise storage systems.

What is a Flash Module?

Flash Modules are custom flash-based data storage components used in high performance storage devices. Flash Modules, used in EMC’s Rack-Scale Flash storage appliances, deliver the highest performance, lowest latency, fastest data transfer rates and highest density flash-based storage. Customers use Flash Module based storage for the best application response time and to unleash the power of analytics for real-time decision making for the business.

What is the difference between flash storage and SSDs or Flash Modules?

Flash storage is a reference to any device that can function as a storage repository. Flash storage can be a simple USB device or a fully integrated All-Flash storage array. SSD—solid state drive—is an integrated device designed to replace spinning media, commonly used in enterprise storage arrays, while a Flash Module is a custom flash storage component used in highest performance flash storage devices, like EMC’s Rack-Scale Flash appliances, instead of SSDs.

What is the difference between flash storage and traditional hard drives?

A traditional hard drive leveraged rotating platters and heads to read data from a magnetic device, comparable to a traditional record player; while flash storage leveraged electronic media, or flash memory, to vastly improve performance. Flash eliminates rotational delay and seek time, functions that add latency to traditional storage media.

What is the difference between an All-Flash Array and a hybrid array?

A hybrid storage array uses a combination of spinning disk drives and flash SSDs. Combined with the right software, a hybrid array can be configured to improve overall performance while reducing cost. An All-Flash array is designed to support only SSD media.

What is Rack-Scale Flash?

Rack-scale flash is a new flash storage architecture that brings flash physically closer to the processors for vastly improved performance – next generation IOPS, latency and throughput. In a rack-scale flash architecture, dense, shared flash memory is connected to client nodes via the highest performance data transport, providing a large, shared pool of high performance storage to multiple client servers. Rack-scale flash provides performance equal to direct attached flash memory combined with the advantages of shared storage, including operational efficiency, enterprise reliability, scalability and centralized management. Rack-scale flash provides today’s and tomorrow’s data and performance intensive workloads with the storage performance they need to maximize business insights and value.

What is the difference between Rack-Scale Flash and hybrid or All-Flash Arrays?

Hybrid or All-Flash-Arrays transfer data between the storage solution and the compute nodes through the network. Storage performance, such as IOPS, latency and throughput, can be limited by network and fabric latencies and I/O bottlenecks. In a rack-scale flash architecture flash storage is brought closer to the CPU and directly connected to the compute nodes utilizing low latency protocols. This architecture, along with data path improvements, provides faster storage performance and greater bandwidth density (bandwidth per terabyte of storage) than traditional flash-based storage arrays.

What is the difference between Rack-Scale Flash and direct attached flash?

Direct attached flash, primarily in the form of SSD’s or PCIe flash cards, provides flash storage that is directly attached to an individual server or computing node. This architecture provides fast storage performance but sacrifice all of the benefits of shared storage. There are many single points of failure, the need to create multiple copies of data to improve reliability and performance, stranded IOPS as data has to move among systems in parallel processing infrastructures, and capacity concerns, which often lead to sacrificing processing power for additional storage space within a server. There are also operational concerns, such as no hot swap of devices and no shared data services. Rack-scale flash provides performance levels equal to PCIe flash cards with the added benefits of a shared storage.

What is XtremIO All-Flash Array?

Deliver breakthrough shared-storage benefits for application acceleration, consolidation, and agility.

  • Linear scale-out performance, consistent sub-millisecond response.
  • Provides writeable snapshots with space efficiency and zero performance impact.
  • Delivers truly inline, always-on data deduplication to reduce capacity needs and TCO.
  • Enables operational and disaster recovery, using native replication with EMC RecoverPoint.

Learn more about  XtremIO All-Flash Array 

What is VMAX All Flash?

Re-architected from the ground up to combine the speed and efficiency of flash with the gold standard of reliability and availability demanded by today’s modern data center.

  • Scale out or scale up to 4 PB with ≈500 microsecond response times.
  • Consolidate open systems, mainframe, IBM i, block, and file data.
  • 99.9999% availability.
  • Simplify planning and deployment with a modern licensing and deployment model.
  • Flash where you need it, cloud where.

Learn more about  VMAX All Flash 

What is Unity All-Flash?

The new standard in midrange storage, EMC Unity is purpose-built to meet the needs of resource-constrained IT professionals in large or small companies.

  • Simple: Rack-and-stack <2 minutes, customer installable, slick HTML5 user interface.
  • Modern: Linux-based architecture, scalable file system, unified snapshots and replication, deep ecosystem integration with VMware, Microsoft, OpenStack, and more.
  • Affordable: Optimized for the best combination of performance, density, and cost. Delivers All-Flash and hybrid configurations at an incredibly low entry-level price.
  • Flexible: Meet any storage deployment requirement—from virtual to purpose-built to converged infrastructure.

Learn more about  Unity All-Flash 

What is DSSD D5?

Meet the performance demands of current and future applications with rack-scale flash-DSSD D5’s ultra-dense, high-performance, and very low latency flash storage.

  • Supplies high-density shared flash.
  • Boosts storage performance with unparalleled IOPS, latency, and throughput.
  • Ensures enterprise-grade availability.
  • Enables native application access for fast access to flash: block driver, direct memory API access, and application API plug-ins.

Learn more about  DSSD D5 Rack-Scale Flash 

What is ScaleIO Ready Node?

Unlock the power of All-Flash to transform the data center for enterprise and modern applications with ScaleIO software defined block storage.

  • Performance: Achieve as much as 8x better IOPS performance compared to traditional SAN vendors.
  • Scalability: Scale from 3 to 1,000+ nodes in a single cluster across multiple racks.
  • Elasticity: Achieve six 9’s availability with no capacity planning, complex reconfigurations, or data migrations.
  • Flexibility: Hypervisor and OS agnostic to provide ultimate agility.
  • Simple: Pre-configured, validated, optimized, distributed, and supported by a single vendor: Dell EMC.

Learn more about  ScaleIO Ready Node 

Flash Storage Definitions

Flash Memory

Flash is non-volatile read/write semiconductor memory which is used in solid state storage devices. Flash stores data bits in cells. Originally flash was designed to hold one bit per cell, which is known as Single Level Cell (SLC) Flash. Subsequent generations of flash products were designed to hold two or more bits per cell. This is called Multi Level Cell (MLC) Flash. Of course, MLC Flash is higher density memory than SLC Flash. The development of Triple Level Cell (TLC) flash and 3-D or vertical NAND (3-D NAND) technologies has resulted in the promise of much higher capacity flash drives at more desirable price points which will meet the surging demand for flash storage in the enterprise.

Garbage Collection

Working in the background, garbage collection accumulates data blocks previously marked for deletion, performs a whole block erasure on each “garbage” block, and returns the reclaimed space for reuse.

SSA (Solid-state Array)

The SSA category is a new subcategory of the broader ECB storage market. SSAs are scalable, dedicated solutions based solely on solid-state semiconductor technology for data storage that cannot be configured with HDD technology at any time. As distinct from SSD-only racks within ECB storage arrays, an SSA must be a standalone product denoted with a specific name and model number, which typically (but not always) includes an operating system and data management software optimized for solid-state technology

SSD (Solid State Drive)

Solid state storage that may utilize traditional HDD form factors such as 3.5-inch, 2.5-inch, or 1.8-inch. Solid state drives typically use storage interfaces such as SATA, SAS, or Fibre Channel.

SSS (Solid State Storage)

Any storage capability that is provided by non-moving memory technology rather than moving magnetic or optical media. solid state storage typically possesses the property of non-volatility and may take various forms such as solid state drives, solid state cards, or solid state modules. Typical interfaces used include SATA, SAS, fibre channel, or PCIe.


A measure of the amount of data that can be transferred from a device (reads) or transferred to a device (writes) within a specified time period, typically measured in megabytes per second (MB/s). Throughput is indicative of the performance of a device in an application generating sequential reads or writes.

Wear Leveling

A set of algorithms utilized by a flash controller to distribute writes and erases across flash cells. The purpose of wear leveling is to delay individual cell wear-out and prolong the useful life of the flash-based storage device.

Write Amplification

Because a previously written NAND flash memory location must be erased before it can be rewritten, the number of write operations within flash solid state device typically exceeds the number of writes issued by the host. This “write amplification” can be represented in equation form: Write Amplification = (Data Written to Flash) / (Data Written by Host.)