storage networking

Storage networking is the practice of linking together storage devices and connecting them to other IT networks. Storage networks provide a centralized repository for digital data that can be accessed by many users, and they use high-speed connections to provide fast performance. It’s most common to find storage networks in enterprise settings, although some vendors do sell networked storage products for consumers and small businesses.

Storage Networking and SAN

The phrase “storage networking” is commonly used in reference to storage area networks (SANs). A SAN links together multiple storage devices and provides block-level storage that can be accessed by servers.

Some people also use the phrase “storage networking” in reference to network attached storage (NAS) devices. Similar to a file server, a NAS array is a standalone device that connects to a network and provides file-level storage that can be accessed by end users.

The benefits of storage networking can include improved performance, reliability and availability. It can enable greater collaboration among workers, and it can simplify some IT management tasks. Storage networks also make it easier to back up data for compliance and disaster recovery purposes. In addition, they can free up valuable server CPU cycles for more important tasks. And although setting up a storage network can be costly, in some cases, it can reduce overall storage costs.

Storage and Other Networks

Storage networking is very similar to other kinds of IT networking. Just as you can connect multiple PCs and servers into a local area network (LAN) or a wide area network (WAN), you can connect multiple storage arrays into a storage area network (SAN).

SANs are often confused with the other common kind of networked storage — NAS devices. In a nutshell, the difference between SAN and NAS is that a SAN is a network, while a NAS array is a device connected to a network. End users don’t save files directly to SANs. Instead, SANs store blocks of data for access by the applications running on servers. By contrast, end users can save files directly to NAS devices.

Making things somewhat more confusing, the lines between SAN and NAS devices are beginning to blur as some vendors release storage appliances with a combination of SAN and NAS capabilities. Many organizations use both SANs and NAS devices, and some connect NAS arrays to their SANs.

The alternative to networked storage is direct attached storage (DAS). Before the advent of storage networking, DAS was the only option for saving digital information. With DAS, a storage device is connected directly to a server or a PC, not to a network. Familiar examples of DAS include a desktop or laptop hard drive, a CD-ROM, a USB memory stick and a hard drive attached directly to an individual server.

Storage Networking Implementation

The process for setting up a storage network will vary depending on whether you are deploying a SAN or a NAS device. Generally, NAS devices are easier to deploy. They connect directly to a LAN via a TCP/IP connection. Some NAS arrays sold for home or small business networks are so easy to deploy that it takes only a few minutes to plug in the cables and configure the network before the devices are up and running.

Deploying a SAN, on the other hand, can be much more complicated. You can create a simple SAN with a storage device, a SAN controller and the appropriate cables. However, in data center environments, a typical SAN will include multiple storage devices, controllers, and networking gear like routers, switches, bridges and gateways, much like you would find in a LAN or WAN. The exact design of the SAN will depend on the needs of the organization and the types of hardware in use. SANs can use a variety of communication protocols, including Fibre Channel (the most common), iSCSI, ATA over Ethernet (AoE), Fibre Channel over Ethernet (FCoE), ESCON over Fibre Channel, HyperSCSI and others.

Storage networks are often used alongside storage management technologies, such as storage resource management software, virtualization, mirroring, and compression.

Storage Networking Technology

An organization called the Storage Networking Industry Association (SNIA) promotes storage networking and establishes standards designed to grow the industry. This group has published the Storage Management Initiative Specification (SMI-S) and numerous related standards.  Another group, the Fibre Channel Industry Association (FCIA), also promotes storage networking and data storage, video, networking and storage area networking (SAN) management technology.

Apple X SAN

A SAN file system for MAC OS X. Apple X SAN enables multiple Mac desktops and Xserve systems to share RAID storage volumes over a high-speed Fibre Channel network.

FC SAN

Short for Fibre Channel Storage Area Network (SAN).

See also Fibre Channel and SAN.

Virtual SAN

Virtual SAN is a software-defined storage offering from VMware that enables enterprises to pool their storage capabilities and to instantly and automatically provision virtual machine storage via simple policies that are driven by the virtual machine.

VMware’s virtual storage area networking (SAN) solution also provides the ability to dynamically scale storage capacity and performance as needed, and exposes the underlying physical storage to the virtual machines through a policy-driven control pane.

VMware’s Virtual SAN, or VSAN, is currently in public beta release and is free for anyone to download.

SAN services

SAN services, short for Storage Area Network (SAN) services, is a technology used by businesses to obtain greater flexibility in their data storage. A Storage Area Network (SAN) provides raw storage devices across a network, and is typically sold as a service to customers who also purchase other services. SAN services may also be administered over an existing, local fibernetwork, and administered through a service subscription plan.

Learn more about SAN services on Datamation.
Learn more about storage networking on Enterprise Storage Forum.

Network Direct Attached Storage – NDAS

Network Direct Attached Storage (NDAS) is a proprietary digital storage technology that utilizes a Lean Packet Exchange (LPX) protocol to connect external digital storage devices to a network via Ethernet or USB. Unlike Network-Attached Storage (NAS), the LPX-based Network Direct-Attached Storage isn’t routable, so the storage hardware can’t be directly accessed via the Internet.

Originally developed by Ximeta in 2003 (and later marketed by IOCELL, which acquired Ximeta’s NDAS technology in 2011), Network Direct-Attached Storage is also different than Network-Attached Storage in that each client requires a software driver in order to access the NDAS storage hardware. The software driver enables any client on the network to directly control, use and share the NDAS device or devices.

Recommended Reading: What Is Enterprise Storage?

Advantages of Network Direct-Attached Storage

The purported advantages of Network Direct-Attached Storage are better performance, lower overhead (no operating system is needed in the device itself), enhanced security and simplified installation and ease of use. A variety of external digital storage devices can be used in Network Direct-Attached Storage form, including hard drives, optical drives, tape drive, flash drives and more.

NDAS vs. DAS, SAN and NAS

Network Direct-Attached Storage stands in contrast to Direct-Attached Storage (DAS) in that the latter refers to storage hardware that cannot be directly connected to a network, but they share the inability to be accessed via the internet. Network-Attached Storage (NAS) and Storage Area Networks (SANs), on the other hand, are more closely related to NDAS in that they both provide access to storage hardware on the network.

The primary difference between Network-Attached Storage and Storage Area Networks is that whereas NAS offers file-level storage reading, SANs are networks composed of storage devices that facilitate block-level storage. NDAS offers both file-level and block-level storage capabilities.

DAS – Direct Attached Storage

DAS is short for direct attached storage.

Direct attached storage (DAS), also called direct attach storage, is digital storage that is attached directly to a computer or a server. In other words, DAS isn’t part of a storage network. The most familiar example of DAS is the internal hard drive in a laptop or desktop PC. In practice, the phrase direct attached storage is used most often in reference to dedicated storage arrays attached directly to servers. It is used to distinguish DAS from networked storage arrangements, like SAN or NAS devices.

DAS Devices Explained

DAS can refer to a single drive or a group of drives that are connected together, as in a RAID array. In addition, DAS devices can be housed inside a PC or server (as is the case with internal hard drives) or outside the PC or server (as is the case with external hard drives and storage appliances). Multiple systems can use the same DAS device, as long as each PC or server has a separate connection to the storage device.

The primary benefits of DAS include simplicity and low cost. Installing networked storage systems, like NAS and SAN devices, requires more planning, as well as the purchase and deployment of network hardware, such as routers and switches, in addition to appropriate cabling and connections. By contrast, most PCs and many servers come with DAS already installed, and if you want to add more direct attached storage, generally all you need to purchase is a storage device and possibly a cable. Maintaining DAS is also very simple; by contrast, SAN and NAS solutions usually require management software and may require monitoring software as well.

The Difference Between DAS, SAN and NAS

In the early days of computing, DAS was the only type of storage available. In fact, the term direct attached storage didn’t come into use until much later when people needed a way to differentiate between traditional storage and SAN and NAS devices.

NAS (network attached storage) offers file-level storage for end users that are connected to a network. The advantage of NAS over DAS is that it simplifies file sharing among multiple users while potentially offering faster performance than a traditional file server.

SAN (storage area network) refers to a network of storage devices that provides block-level storage for servers in a data center. For large organizations with many servers, SAN offers better performance and flexibility than DAS, along with potential cost savings, although SAN hardware can be costly.

Many SAN and NAS devices can also be used as DAS devices. The difference lies in whether they are attached directly to a server or attached to a network via routers and switches.

Recommended Reading: What is Enterprise Storage?

Direct Attached Storage Implementation

Setting up a DAS device is generally very simple. When you purchase a PC, DAS is included in the form of the hard drive. If you would like to add more direct attached storage to a laptop or desktop, you can attach a plug-and-play external hard drive.

DAS is also included in many servers. Connecting additional DAS devices to servers is a little more complicated than adding DAS to a PC, but it is generally simpler than connecting SAN or NAS devices because it doesn’t require you to design a network or purchase hardware like routers and switches. Depending on the type of server, you may be able to add DAS in the form of additional drives in your existing server chassis. Other times, DAS sits in a separate chassis. You can also purchase DAS as storage appliances that you can connect directly to your servers. DAS deployment may require some configuration, but most IT workers can handle it on their own without outside consultants or specialized technical experts.

Using DAS is very easy. You simply save files as usual. Your operating system will allow you to view, rename, delete and perform other operations on the files on your DAS.

DAS Technology

DAS devices can utilize traditional spinning hard disk drives or solid state media. Hard disk drives (HDDs) are less expensive than solid state drives (SDDs) on a per gigabyte basis. However, they aren’t as fast as SDDs. The majority of DAS devices sold today use hard disk drives, although SSDs and hybrid devices are becoming more popular, particularly for applications where performance is paramount, such as Big Data analytics.

Conversely, SSDs offer the fastest performance, but they are also the most expensive. However, in recent years, they have become more affordable. In addition, because SSDs don’t have a spinning disk, they last longer and offer better reliability than HDDs. Many vendors now offer SSDs as an option on mid- to high-end servers for part or all of the storage capacity.

DAS devices can connect to PCs and servers via a variety of protocols, including SCSI, SAS, SATA, ATA, eSATA and Fibre Channel.

SAN fabric

The hardware that connects workstations and servers to storage devices in a SAN is referred to as a “fabric.” The SAN fabric enables any-server-to-any-storage device connectivity through the use of Fibre Channel switching technology.

storage management

The term storage management encompasses the technologies and processes organizations use to maximize or improve the performance of their data storage resources. It is a broad category that includes virtualization, replication, mirroring, security, compression, traffic analysis, process automation, storage provisioning and related techniques.

By some estimates, the amount of digital information stored in the world’s computer systems is doubling every year. As a result, organizations feel constant pressure to expand their storage capacity. However, doubling a company’s storage capacity every year is an expensive proposition. In order to reduce some of those costs and improve the capabilities and security of their storage solutions, organizations turn to a variety of storage management solutions.

Storage Management Benefits

Many storage management technologies, like storage virtualization, deduplication and compression, allow companies to better utilize their existing storage. The benefits of these approaches include lower costs — both the one-time capital expenses associated with storage devices and the ongoing operational costs for maintaining those devices.

Most storage management techniques also simplify the management of storage networks and devices. That can allow companies to save time and even reduce the number of IT workers needed to maintain their storage systems, which in turn, also reduces overall storage operating costs.

Storage management can also help improve a data center’s performance. For example, compression and technology can enable faster I/Os, and automatic storage provisioning can speed the process of assigning storage resources to various applications.

In addition, virtualization and automation technologies can help an organization improve its agility. These storage management techniques make it possible to reassign storage capacity quickly as business needs change, reducing wasted space and improving a company’s ability to respond to evolving market conditions.

Finally, many storage management technologies, such as replication, mirroring and security, can help a data center improve its reliability and availability. These techniques are often particularly important for backup and archive storage, although they also apply to primary storage. IT departments often turn to these technologies for help in meeting SLAs or achieving compliance goals.

Storage Management: Related Terms

Storage management is very closely related to Storage Resource Management (SRM). SRM often refers particularly to software used to manage storage networks and devices. By contrast, the term “storage management” can refer to devices and processes, as well as actual software. In addition, SRM usually refers specifically to software for allocating storage capacity based on company policies and ongoing events. It may include asset management, charge back, capacity management, configuration management, data and media migration, event management, performance and availability management, policy management, quota management, and media management capabilities. In short, SRM is a subset of storage management; however, the two terms are sometimes used interchangeably.

Storage management is also closely associated with networked storage solutions, such as storage area networks (SANs) and network-attached storage (NAS) devices. Because using SAN and NAS devices is more complicated than using direct-attached storage (DAS), many organizations deploy SRM software when they deploy their storage networking environments. However, storage management techniques like replication, mirroring, security, compression and others can be utilized with DAS devices as well as with SANs and NAS arrays.

Storage management is often used in virtualized or cloud computing environments.

Storage Management Implementation

Because storage management is such a broad category, it’s difficult to provide detailed instructions on how to install or how to use storage management technologies. In general, storage management technology can be deployed as software or it can be included in a hardware device. Storage management techniques can be applied to primary, backup or archived storage. Deployment and implementation procedures will vary widely depending on the type of storage management selected and the vendor. In addition, the skills and training of storage administrators and other personnel add another level to an organization’s storage management capabilities.

Storage Management Technology

The primary organization involved in establishing storage management standards is the Storage Networking Industry Association (SNIA). It has put forth several important storage specifications, including the Storage Management Initiative Specification (SMI-S) and the Cloud Data Management Interface (CDMI). SMI-S defines the attributes of storage hardware, such as Fibre Channel switches, Fibre Channel and iSCI arrays, NAS devices, tape libraries and host profiles. It also addresses storage management software issues, such as configuration discovery, provisioning and trending, security, asset management, compliance and cost management, event management and data protection. The CDMI specification provides standards for cloud storage services, enabling interoperability among various storage management solutions.

The work of the SNIA builds on previous work done by the Distributed Management Task Force (DMTF), which has also been involved in establishing storage management standards.