SAN Explained — Storage (Or System) Area Network

What are storage area networks used for?

A SAN is simply a network of disks that are accessed by a network of servers. SANs are widely used in enterprise computing for a variety of purposes. A SAN is commonly used to consolidate storage. A computer system, such as a server, may, for example, include one or more local storage devices. Consider a data center with hundreds of servers, each running virtual machines that can be deployed and migrated from server to server as needed. If the data for one workload is stored on that local storage, the data may need to be moved or restored if the workload is migrated to another server. Rather than attempting to organize, track, and use the physical disks in individual servers throughout the data center, a company may choose to move storage to a dedicated storage subsystem, such as a storage array, where it can be collectively provisioned, managed, and protected.

A storage area network (SAN) can also improve storage availability. Because a SAN is essentially a network fabric of interconnected computers and storage devices, a disruption in one network path is usually mitigated by enabling an alternate path through the SAN fabric. As a result, a single cable or device failure does not render storage unavailable to enterprise workloads. Furthermore, the ability to treat storage as a shared resource can improve storage utilization by removing “forgotten” disks from underutilized servers. A SAN, on the other hand, provides a centralized location for all storage and allows administrators to pool and manage storage devices together.

By improving IT’s ability to support enterprise workloads, all of these use cases can improve the organization’s regulatory compliance, disaster recovery (DR), and business continuity (BC) postures. However, in order to fully appreciate the value of SAN technology, it is necessary to first understand how a SAN differs from traditional DAS.

DAS connects one or more disks to a specific computer via a dedicated storage interface, such as SATA or SAS. Disks are frequently used to store applications and data designed to run on that specific server. Although DAS devices on one server can be accessed from other servers, communication takes place over a shared IP network (the LAN) alongside other application traffic. Accessing and moving large amounts of data over a standard IP network can be time-consuming, and the bandwidth demands of large data movements can impact server performance.

A SAN works in a completely different way. The SAN connects all disks to form a dedicated storage area network. That dedicated network exists independently of the common LAN. This approach allows any of the servers connected to the SAN to access any of the SAN’s disks, effectively treating storage as a single collective resource. None of the SAN storage data must pass through the LAN, reducing LAN bandwidth requirements and preserving LAN performance. Because the SAN is a separate dedicated network, it can be designed to prioritize performance and resilience, both of which are advantageous to enterprise applications.

A storage area network (SAN) can support a large number of storage devices, and storage arrays (specially designed storage subsystems) that support a SAN can scale to hold hundreds or even thousands of disks. Similarly, any server with a suitable SAN interface can access the SAN and its vast storage capacity, and a SAN can support a large number of servers. Fiber Channel and iSCSI are the two most common networking technologies and interfaces used in SANs.

1. Fiber Channel: FC is a high-speed network known for its high throughput and low latency, with data rates of up to 128 Gbps available across metropolitan area distances of up to 6 miles (10 km) when optical fiber cabling and interfaces are used. This type of dedicated network may allow for the consolidation of block level storage in a single location, while servers can be distributed across campus buildings or a city. Traditional copper cabling and FC interfaces can also be used when storage and servers are in the same location and distances are less than 100 feet (10 meters). FC naming and throughput designations have recently changed to Gigabit FC, and the latest interface iterations promise 128 and 256 GFC, respectively. FC, like modern Ethernet, supports a variety of network topologies, including point-to-point, arbitrated loop, and switched fabric. FC is implemented by putting FC host bus adapters (HBAs) in every server, storage device, FC network switch, and other network device. Each HBA has one or more ports through which data is exchanged. Virtual and physical ports can be interconnected via cables, allowing HBAs and switches to form a network fabric.

2. ISCSI: The iSCSI network is another type of network that connects computing to shared storage. It can reach speeds of up to 100 Gbps but offers several benefits to data center operators. Whereas FC provides a one-of-a-kind and highly specialized network design, iSCSI combines traditional SCSI block data and command packets with standard Ethernet and TCP/IP networking technology. This allows iSCSI storage networks to use the same cabling, network adapters, switches, and other network components as any other Ethernet network; in many cases, iSCSI can operate on the same Ethernet LAN (without a separate LAN) and exchange data across the LAN, WAN, and even the internet. The iSCSI data access is viewed by each server’s operating system as just another locally connected SCSI disk. ISCSI works on the basis of initiators and targets. An initiator is usually a server that is a member of the iSCSI SAN and sends SCSI commands over an IP network. Initiators can be software- or hardware-based, such as an operating system or a storage array. A target is typically a storage resource, such as a dedicated, network-connected hard disk storage device, but it can also be another computer.

How a storage area network works

A storage area network is essentially a network that connects servers and storage. The goal of any SAN is to move storage away from individual servers and into a collective location where storage resources can be managed and protected centrally. Physical centralization can be accomplished by placing disks in a dedicated storage subsystem, such as a storage array. However, centralization is increasingly being handled logically through software, such as VMware vSAN, which uses virtualization to find and pool available storage.

Storage traffic performance can be optimized and accelerated by connecting collective storage to servers via a separate network – separate from the traditional LAN – because storage traffic no longer needs to compete for LAN bandwidth required by servers and their workloads. Thus, enterprise workloads may benefit from faster access to massive amounts of storage. A SAN is commonly viewed as having three distinct layers: a host layer, a fabric layer, and a storage layer. Each layer has its own set of components and properties.

1. Host layer. The servers connected to the SAN are represented by the host layer. In most cases, the hosts — servers — are running enterprise workloads that require storage, such as databases. Hosts typically use traditional LAN — Ethernet — components to connect the server and its workload to other servers and users. SAN hosts, on the other hand, include a dedicated network adapter for SAN access. A host bus adapter is the network adapter used in the majority of FC SANs (HBA). The FC HBA, like most network adapters, uses firmware to operate the HBA’s hardware, as well as a device driver to connect the HBA to the server’s operating system. This configuration enables the workload to communicate storage commands and data to the SAN and its storage resources via the operating system. FC is one of the most popular and powerful SAN technologies available, but InfiniBand and iSCSI are also widely accepted. Each technology has its own set of costs and tradeoffs, so when choosing a SAN technology, the organization must carefully consider its workload and storage requirements. Finally, the SAN technology used by the host, fabric, and storage layers must be the same.

2. Fabric layer. The cabling and network devices that comprise the network fabric that connects the SAN hosts and SAN storage are represented by the fabric layer. Within the fabric layer, SAN networking devices such as SAN switches, gateways, routers, and protocol bridges can be found. Cabling and SAN fabric device ports can use optical fiber connections for long-distance network communication or traditional copper-based network cables for close-range local network communication. The distinction between a network and a fabric is redundancy: the presence of multiple alternate paths from hosts to storage across the fabric. Multiple connections are typically implemented when constructing a SAN fabric to provide multiple paths. SAN communication will use an alternate path if one path is damaged or disrupted.

3. Storage layer. The storage layer is made up of various storage devices organized into storage pools, tiers, or types. Traditional magnetic HDDs are typically used for storage, but SSDs and optical media devices such as CD and DVD drives, as well as tape drives, can also be used. The majority of storage devices in a SAN are organized into physical RAID groups, which can be used to increase storage capacity, improve storage device reliability, or both. Each logical storage entity, such as RAID groups or disk partitions, is assigned a unique LUN that serves the same basic purpose as a disk drive letter, such as C or D. As a result, any SAN host has the potential to access any SAN LUN across the SAN fabric. An organization can permit which host can access specific LUNs by organizing storage resources and designating storage entities in this manner, allowing the business to exert granular control over the organization’s storage assets. LUN masking and zoning are the two most basic methods for controlling SAN permissions. Masking is essentially a list of LUNs that cannot or should not be accessed by a SAN host. Zones, on the other hand, control host access to LUNs by configuring the fabric itself, limiting host access to storage LUNs that are in an approved SAN zone.

A SAN also employs a set of protocols that allow software to communicate with one another and prepare data for storage. The Fiber Channel Protocol (FCP), which maps SCSI commands over FC technology, is the most commonly used protocol. The iSCSI SANs will use an iSCSI protocol that translates SCSI commands to TCP/IP. However, other protocol combinations exist, such as ATA over Ethernet, which maps ATA storage commands over Ethernet, as well as Fiber Channel over Ethernet (FCoE) and other less-used protocols, such as iFCP, which maps FCP over IP, and iSCSI Extensions for RDMA, which maps iSCSI over InfiniBand. SAN technologies frequently support multiple protocols, ensuring that all layers, operating systems, and applications can communicate effectively.

Configuring the storage area network

To integrate all SAN components, an enterprise must first satisfy the vendor’s hardware and software compatibility requirements:

• host bus adapters (firmware and driver versions, as well as a patch list);
• firmware switch; and
• storing (firmware, host personality firmware and patch list).

Then, in order to configure the SAN, you must do the following:

1. Assemble and connect all of the hardware components, then install the necessary software.

1. Check the versions.
2. Set up the HBA.
3. Set up the storage array.

2. Change any configuration settings that may be necessary.

3. Test the integration.

1. 1. All SAN operational processes, including normal production processing, failure mode testing, and backup, must be tested.

4. Create a baseline performance for each component as well as the entire SAN.

5. Make a record of the SAN installation and operational procedures.

Applications of Storage Area Network

These applications may be horizontal (like backup, archiving, data replication, disaster protection, and data warehousing) or vertical (like online transaction processing (OLTP), enterprise resource planning (ERP) business applications, electronic commerce, broadcasting, prepress, medical, and geophysics). SAN is also a good way to make performance and high availability in applications like clustering and data sharing more scalable and more affordable. This article talks about backup and data sharing, two major horizontal applications, and how they work with SAN.

Backing up in a SAN setting

When users set up storage area network, one of the first things they want is to be able to back up and protect their data through SAN. They want to get heavy backup traffic off the LAN, free up system bandwidth for production operations, and get the speed and security benefits of centralized management that SAN offers.

To protect data on a storage area network effectively, you need a number of things. Many of them are just starting to be put into place right now. These things are:

Centralized management

• Help with sharing libraries of removable media
• Backup without a LAN or a server
• Heterogeneous platform support
• Mirroring and vaulting from a distance
• Back up in real time

Centralized management: In an ideal world, all the logical and physical storage resources of an enterprise network would be managed from one central console. All information about capacity, configuration, use, and performance for all storage resources would be automatically collected, linked, and analyzed by the console. File systems, directories, files, and application-specific storage repositories would be some of the logical resources that would be monitored. Disks, RAID systems, tape libraries, optical jukeboxes, Fibre Channel parts, Network Attached Storage (NAS), and SAN switches and hubs would be some of the physical resources that would be tracked. Almost all vendors offer centralized management in some way. Veritas, Legato, Computer Associates (CA), and IBM are the top firms in this area.

Support for sharing libraries of removable media: When doing backups, it is often necessary to back up many different servers to tape drives that are connected locally. SAN and NAS connectivity makes it possible for multiple backup servers to share resources, such as a large tape library. Administrators can put all of the backups in one tape library if they can share resources.

But the support must include more than just connecting to a library. It must also include management. Managing a library means managing access to the media stored in it. This requires dynamic drive allocation among servers, so that the server that needs a drive the most at a given time can get it (e.g., when recovering a large database). Managing a library means taking care of not only backup but also any application that might need access to tape or optical storage.

In many cases, the cost of automation will be worth it because the SAN makes it possible to connect a library to multiple backup servers. In this situation, it makes economic sense to use Hierarchical Storage Management (HSM). Legato, Veritas, CA, and Seagate Software are the leaders in developing support for shared tape libraries.

LAN-less and server-less backup: When it comes to moving data, backup has gone through three stages. Currently, in the first phase, data moves from the disk to the server it is directly connected to, over the LAN, to another server, which then sends the data to the tape. SAN lets you do backups outside of the LAN in the second phase. Data moves from the disk to the server, which sends it back to a SAN-connected library through the SAN. This kind of backup system is sometimes called LAN-less backup. In the third step, the backup command is run by the server. Through the SAN fabric, data goes straight from the disk to the tape without going through the server or the LAN. This is called “backup without a server.” Intelliguard, which Legato just bought, was the first company to develop backup without a server.

Support for different kinds of platforms: Most early SAN implementations are all the same. As SAN environments get older, they will have more different kinds of hardware. Effective SAN management software will be able to handle any server from any vendor talking to any storage from any vendor, hosting any database, application, or file system, and backing up to any tape drive or library through any switch, hub, router, or bridge. EMC and Veritas are two examples of vendors that support platforms from different companies.

Remote vaulting and mirroring: Fibre Channel makes it easier to set up remote sites for business continuity and disaster recovery because it allows connections from 10 to 20 km away, depending on how they are used. Because of this, people are likely to use remote backup, remote vaulting, and remote mirroring more. SANs can also be linked to WANs to get even more protection and connectivity. CommVault is one of the companies that lets you do remote vaulting. CNT has a SAN-to-WAN solution for SCSI connectivity and Enterprise Systems Connectivity (ESCON), and it is also working on adding support for remote Fibre Channel.

Real-time backup, also called “window-less” or “hot” backup, is important when it comes to dealing with the large amount of data in a centralized SAN backup library. Real-time backup lets you back up a volume or file automatically and on a regular basis without affecting how the rest of the system works. Most people use a method called a “snapshot,” in which they make a copy of the volume that needs to be backed up, then back up the copy while continuing to use and change the original volume as usual. Network Integrity is the leader in development, and both EMC and HDS have built solutions into products that are already on the market. ADIC, ATL, StorageTek, Hewlett-Packard (HP), Exabyte, and Overland are some of the largest companies that offer full backup solutions.

Resource and data sharing

In a heterogeneous environment, in which platforms are different by definition, it is important to tell the difference between sharing resources, sharing copies of data, and sharing real data.

Sharing resources: A storage subsystem that is connected to multiple computer platforms is split into partitions. Each partition can only be accessed by the platform that owns it or by a certain number of platforms that are the same. As needs change, the administrator can move storage space to different platforms. One of the benefits of SAN connectivity is that it lets many backup servers share resources, like a large tape library. Sharing like this lets administrators put all of the backups from many different servers and tape drives that are connected locally into one tape library.

Dynamic resource sharing: Dynamic resource sharing means that all storage is available to any host that is connected, and storage is given to hosts as they need it. If a host needs the storage space, it can use as much or as little of it as it wants. If a host deletes a file, any other host can use that space. This sharing of dynamic storage happens automatically and without being noticed. With dynamic resource sharing, the systems administrator doesn’t have to divide the storage space into sections before putting the data there.

Data copy sharing: In this process, the data is copied twice. When a copy is made, the data is the same for all copies, but copies can change on their own after that. No one can say for sure that they will stay the same. During replication, data access is usually blocked, so that the copy shows all the data as it was at a certain time. For large amounts of data, the time it takes to copy it may be important, and the amount of space needed to store the copy could be very large. SAN makes it easier to share copies of data by letting high-bandwidth connections move large amounts of data.

True data sharing: If you share data without making a copy, multiple computer platforms can access the same physical copy of the data stored on a storage subsystem. This is what is known as “true data sharing.” True data sharing can be done at different levels of performance and complexity: The first level is when data can be accessed by different platforms, but only the owner of the original data can change it. The second level is when more than one different type of platform can update or change a piece of data, but only one at a time. In this case, you need a locking mechanism to stop a platform from updating the data for a short time. The third level is called “concurrent data sharing,” and it happens when all platforms can either read the data or change it at the same time. There are many benefits to sharing data in a real way. With only one copy of data, you never have to duplicate it to use it somewhere else. This makes data maintenance easier and gets rid of problems caused by data that isn’t in sync. To really share data between platforms with different operating systems, you have to translate to a single operating system (see File management discussion under SAN Management Software on page XX). Sequent, Mercury Computer Systems, DataDirect, Transoft, Retrieve, and Network Disk are all examples of companies that offer implementations of true data sharing in a SAN architecture. NetApp, EMC, Sun, IBM, and Procom all have real solutions for sharing data in a NAS architecture.

Types of Storage Area Network

The various types of Storage Area Networks are given below:

1. Fibre Channel Protocol (FCP) (FCP)

Fibre Channel Protocol is used to transfer the data with very high speed between the initiators and the target i.e. between the client and the storage system. In these, all the cluster of storage devices is connected to the switch with the cables. It has a bandwidth between 2- 16 Gigabytes per second.

2. Internet Small Computer System Interface (iSCSI) (iSCSI)

SCSI is a system that can interact with storage media. Like if you get a hard drive – it is connected by SCSI. iSCSI is the ability to access the network drive remotely by using TCP protocol.

3. Fibre Channel over Ethernet (FCoE) (FCoE)

Fibre Channel over Ethernet (FCoE) is used as a medium for the traffic of LAN and SAN which will result in the less no. of server adapters. Like in LAN we use NIC (Network Interface card ) as an adapter and in SAN there is HBA ( Host box adapters) but in FCoE – we will be using only one adapter i.e. CNA ( converged network adapter) which has the understanding to differentiate between the SAN and LAN traffic.

4. Non-Volatile Memory Express over Fibre Channel (FC-NVMe) (FC-NVMe)

NVme used for higher scalability, efficiency and low latency. It can transfer the data with 20 microseconds or less.

Architecture and operation of a SAN fabric

A SAN’s fabric is the scalable, high-performance network that connects hosts (servers) and storage devices or subsystems. The fabric’s design is directly responsible for the SAN’s dependability and complexity. At its most basic, an FC SAN can simply connect HBA ports on servers to corresponding ports on SAN storage arrays, often using optical cables for maximum speed and support for networking over longer physical distances.

However, such simplistic connectivity schemes obscure the true power of a SAN. In reality, the SAN fabric is intended to improve storage reliability and availability by removing single points of failure. A key strategy in building a SAN is to use at least two connections between any SAN elements. The goal is to always have at least one operational network path between SAN hosts and SAN storage.

Consider the following simple example, in which two SAN hosts must communicate with two SAN storage subsystems. Because the HBA device itself is a single point of failure, each host uses a separate HBA rather than a multiport HBA. Each HBA’s port is connected to a port on a different SAN switch, such as a Fibre Channel switch. Similarly, multiple SAN switch ports connect to various storage target devices or systems. This is a simple redundant fabric; if any of the connections in the diagram are removed, both servers can still communicate with both storage systems, preserving storage access for both servers’ workloads.

Consider the fundamental characteristics of a SAN and its fabric. A host server requires SAN storage; the host will generate an internal request to access the storage device. The traditional SCSI commands used for storage access are encapsulated into network packets, in this case FC packets, and the packets are structured according to the FC protocol rules. The packets are delivered to the host’s HBA, which places them on the network’s optical or copper cables. The HBA sends the request packet(s) to the SAN, where it is received by the SAN switch (es). One of the switches will receive the request and forward it to the appropriate storage device. The storage processor in a storage array will receive the request and interact with the array’s storage devices to accommodate the host’s request.

SAN switch comprehension

The SAN switch is the hub of any SAN. The SAN switch, like most network switches, receives a data packet, determines its source and destination, and then forwards it to the intended destination device. Finally, the number of switches, the type of switches (such as backbone switches, modular or edge switches), and the way the switches are interconnected define the SAN fabric topology. Modular switches with 16, 24, or even 32 ports may be used in smaller SANs, while backbone switches with 64 or 128 ports may be used in larger SANs. SAN switches can be linked together to form large, complex SAN fabrics that connect thousands of servers and storage devices.

Storage resilience cannot be ensured solely through the use of a fabric. In practice, storage systems must include a variety of internal technologies, such as RAID — disk groupings for increased capacity and resilience — as well as robust error handling and self-healing capabilities. Thin provisioning, snapshots or storage cloning, data deduplication, and data compression are typical additions to the storage system for efficient storage utilization. Although a well-designed SAN fabric allows any host to connect to any storage device, isolation techniques such as zoning and LUN masking can be used to limit host access to some LUNs for improved storage performance and security across the SAN.

Alternative SAN strategies

SAN technology has been available for decades, but there have been several enhancements and dedicated improvements that have reshaped SAN design and deployment. Virtual SAN, unified SAN, converged SAN, and hyper-converged infrastructure are some of the alternatives (HCI).

Virtual SAN. Virtualization technology was a natural fit for the SAN, encompassing both storage and storage network resources to increase the underlying physical SAN’s flexibility and scalability. A virtual SAN, denoted with a capital V in VSAN, is a type of isolation reminiscent of traditional SAN zoning, in which virtualization is used to create one or more logical partitions or segments within the physical SAN. Traditional VSANs can use isolation like this to manage SAN network traffic, improve performance, and increase security. Thus, VSAN isolation can keep potential SAN problems from affecting other SAN segments, and the segments can be changed logically as needed without touching any physical SAN components. VMware provides virtual SAN technology, denoted by a small v in vSAN, that expands on basic VSAN approaches to provide advanced features such as storage pooling or tiering — detecting and organizing storage across hosts — and non-disruptive data migration — moving storage from one platform to another without affecting the applications that rely on that data. VMware vSAN can also support information lifecycle management, which allows vSAN to automatically move data from one storage performance tier to another based on how the data is accessed. For example, frequently accessed data can be placed on a high-performance storage tier, then moved to a lower tier as it becomes less frequently accessed, and finally relegated to an archival storage tier as it becomes obsolete.

Unified SAN. A SAN is distinguished by its support for block storage, which is common in enterprise applications. However, file, object, and other types of storage have traditionally necessitated the use of a separate storage system, such as network-attached storage (NAS). A unified storage SAN can support multiple approaches, such as file, block, and object-based storage, within the same storage subsystem. Unified storage achieves this by supporting multiple protocols, including file-based SMB and NFS, as well as block-based protocols like FC and iSCSI. Users can take advantage of powerful features normally reserved for traditional block-based SANs by using a single storage platform for block and file storage, such as storage snapshots, data replication, storage tiering, data encryption, data compression, and data deduplication, by using a single storage platform for block and file storage. Different storage protocols, on the other hand, place varying demands on the storage system, resulting in variable storage performance. File-based data access, for example, can take longer and be more random than block-based data access. Some enterprise class applications may benefit from the dedicated performance characteristics of block-based SAN despite the variable demands of unified storage systems.

Converged SAN. The cost and complexity of a separate network dedicated to storage is a common disadvantage of a traditional FC SAN. ISCSI is one method of reducing SAN costs by utilizing common Ethernet networking components rather than FC components. FCoE enables a converged SAN that can run FC communication directly over Ethernet network components, bringing together common IP and FC storage protocols on a single low-cost network. FCoE routes and transports FC data across an Ethernet network by encapsulating FC frames within Ethernet frames. However, FCoE relies on end-to-end support in network devices, which has been difficult to achieve on a large scale, limiting vendor choice. Furthermore, FCoE alters how networks are implemented and managed, particularly in terms of authentication and security for corporate data, and organizations have been hesitant to make such changes to traditional policies and processes.

Hyper-converged infrastructure. The use of HCI in data centers has increased dramatically in recent years. HCI combines compute and storage resources into pre-packaged modules that can be added as needed and managed by a single common utility. Virtualization is used in HCI to abstract and pool all compute and storage resources. The available resource pools are then used by IT administrators to provision virtual machines and storage. HCI’s primary goal is to simplify hardware deployment and management while allowing for rapid scalability. HCI 2.0 separates storage and compute resources, essentially providing storage and compute in their own nodes, allowing compute and storage to be scaled separately while maintaining the same underlying goals. HCI is not a SAN, but it can be used in place of or alongside traditional enterprise SANs depending on the demands of current enterprise workloads.

Storage area network advantages

A SAN, whether traditional or virtual, provides several compelling advantages that are critical for enterprise-class workloads.

• High performance. A typical SAN employs a dedicated network fabric for storage tasks. For maximum performance, the fabric is typically FC, but iSCSI and converged networks are also available.
• High scalability. The SAN can support massive deployments involving thousands of SAN host servers, storage devices, and even storage systems. New hosts and storage can be added as needed to expand the SAN to meet the specific needs of the organization.
• High availability. A traditional SAN is built around the concept of a network fabric, which connects everything to everything else. This means that a fully-featured SAN deployment has no single point of failure between a host and a storage device, and communication across the fabric can always find an alternate path to keep storage available to the workload.
• Advanced management features. A SAN will support a variety of useful enterprise-class storage features, such as data encryption, deduplication, storage replication, and self-healing technologies, all of which are designed to maximize storage capacity, security, and data resilience. Features are nearly universally centralized and can be easily applied to all SAN storage resources.

SAN disadvantages

However, despite their benefits, SANs are far from perfect, and there are a number of potential drawbacks that IT leaders should consider before deploying or upgrading a SAN.

Complexity. Although more convergence options for SANs exist today, such as FCoE and unified options, traditional SANs add the complexity of a second network, complete with costly, dedicated HBAs on host servers, switches and cabling within a complex and redundant fabric, and storage processor ports at storage arrays. Such networks must be carefully designed and monitored, but the complexity is becoming increasingly difficult for IT organizations with fewer staff and lower budgets.

Scale. Given the cost, a SAN is generally only effective in larger and more complex environments with many servers and significant storage. A SAN can certainly be implemented on a small scale, but the cost and complexity are difficult to justify. Smaller deployments can often achieve satisfactory results with an iSCSI SAN, a converged SAN over a single common network (such as FCoE), or an HCI deployment that is adept at resource pooling and provisioning.

Management. With the emphasis on hardware complexity, there is also a significant challenge in SAN management. Configuring features like LUN mapping and zoning can be difficult for busy organizations. Setting up RAID and other self-healing technologies, as well as corresponding logging and reporting, not to mention security, can be time-consuming, but it is necessary to maintain the organization’s compliance, disaster recovery, and business continuity postures.

Storage area network vs NAS

Network-attached storage (NAS) is a method of storing and accessing data that uses file-based protocols such as SMB and NFS rather than the block-based protocols used in SANs such as FC and iSCSI. Other distinctions exist between a SAN and a NAS. Whereas a SAN connects servers and storage via a network, a NAS relies on a dedicated file server located between servers and storage.

Although both approaches store data, the system chosen will be determined by the type of data being handled. A SAN is the preferred option for block-based data storage, which is typically applicable to structured data, such as storage for enterprise-class relational database applications. A NAS, on the other hand, is better suited to unstructured data, such as document files, emails, images, videos, and other common types of files, due to its file-based approach.

A NAS, like a SAN, consolidates storage in one location and can help with data management and protection tasks like data archiving and backup. NASs, on the other hand, use a common network and have far lower costs and complexity than SANs. SANs, on the other hand, stand out in terms of raw performance and scalability, delivering top performance to the most demanding enterprise applications.

The terms SAN and NAS are not mutually exclusive. When both block- and file-based data storage is required, a SAN and NAS can coexist in the same data center. SAN and NAS deployments can both be upgraded to improve performance, simplify management, combat shadow IT, and address storage capacity constraints. Separate storage systems may be replaced with a unified storage system in some cases, or the SAN network may be simplified by using an iSCSI SAN.

Major vendors and products

There are numerous vendors and products available to support enterprise SAN deployments. When designing a SAN, architects typically take into account the hosts (servers), network (fabric), components, and storage subsystems.

Hosts. The storage area network can be used by any host, but each host server must have a suitable network interface to access the fabric. Enterprise-class servers can be purchased with multi-port FC HBAs preinstalled, which is a common strategy for technology refresh projects. If the servers do not already have an HBA, one can be added as part of a server upgrade project. Adding an HBA as an aftermarket upgrade, on the other hand, will necessitate the availability of a PCIe slot on the server’s motherboard. Before purchasing and proceeding with the upgrades, IT staff must survey each target server to ensure that a suitable upgrade slot is physically available. Furthermore, such upgrades will require the server to be powered down, so IT staff must plan for server downtime and such disruptive upgrades.

HBA cards are commonly built on core communications chips from industry leaders such as Agilent, ATTO, Broadcom, Brocade, and QLogic. HBAs are manufactured and sold by a variety of technology vendors and procurement channels.

Network. The SAN fabric is made up of optical or copper cabling as well as networking components like network switches. Cabling, like HBAs, is widely available from common technology vendors and procurement channels. Based on the technologies used by major chip and technology manufacturers, both edge and director switches can be found. The following are some examples:

• ATTO Technology 8308, 8316 and 8324 switches;
• Brocade G-series switches and DCX-series directors;
• Cisco MDS-series switches, Nexus 5672UP and MDS-series directors;
• Juniper QFabric QFX-series switches; and
• QLogic SANbox 5xxx-series switches and SANbox 9xxx directors.

Storage. Storage arrays receive attention in the SAN because storage is the entire point of SAN technology, and storage subsystems possess many of the functions that make SANs so appealing to enterprises (deduplication, replication, and so on). Here are a few examples of major storage array vendors:

• Dell EMC’s product lines include Isilon NAS storage, EMC Unity hybrid-flash storage arrays for block and file storage, SC series arrays, and VMAX storage products.
• Hitachi Data Systems provides the Hitachi NAS Platform as well as the G Series arrays.
• HPE StoreEasy Storage NAS systems and flash-enabled MSA Storage, as well as HPE 3PAR StoreServ midrange arrays, are among the company’s product lines.
• Huawei provides all-flash Ocean Stor Dorado V3 arrays and hybrid-flash OceanStor 18000 V5 storage systems.
• IBM offers disk and flash storage arrays, including the DS family, XIV family, and Scale Out Network Attached Storage system, as well as numerous Flash System variants.
• NetApp’s all-flash arrays support low-latency NVMe-over-Fabrics, and its On Tap storage software supports hybrid cloud data tiering.

Fujitsu, Lenovo, Oracle, and Western Digital are some other notable SAN storage vendors. Kaminario, Pure Storage, IntelliFlash (formerly Tegile), and Violin Systems are among the newer SAN vendors focusing on all-flash storage.

Don’t overlook the potential value of SAN as a service when it comes to storage. The idea is similar in principle to any cloud or SaaS offering, which is sold to customers as a managed service. A provider constructs and manages a SAN before selling capacity on that SAN to third-party customers. Customers can access one or more LUNs created for them on the provider’s SAN, usually for a recurring monthly fee, and the provider is responsible for building and maintaining the SAN and its features such as replication. SAN services are frequently sold in tandem with other managed data services.

SAN technology standards

Several industry groups, including the Storage Networking Industry Association, have developed storage area network technology standards, such as the Storage Management Initiative Specification. The SMI-S standard, as it is known, is intended to make storage device management in storage area networks easier.

The Fiber Channel Industry Association also promotes SAN standards, such as the Fiber Channel Physical Interface standard, which supports 64 GFC deployments, and Gen 7 solutions for the SAN market, which is the fastest industry standard networking protocol, enabling storage area networks of up to 128 GFC.

SAN management

A SAN presents significant management challenges. The physical network can be complicated and must be constantly monitored. Furthermore, the logical network configuration, such as LUN masking, zoning, and SAN-specific functions like replication and deduplication, can change and necessitate frequent attention. SAN administrators should consider several management best practices to keep the storage area network running at peak performance.

Some of the most important practices will rely on SAN monitoring and reporting. Administrators should review metrics or key performance indicators (KPIs) in the following areas of the SAN:

• any KPIs related to specific storage array subsystems, such as the read/write throughput for every array;
• any KPIs related to the SAN fabric, or network, such as low or no buffer credits at a SAN switch or orphaned ports as zoning changes are implemented over time;
• any KPIs related to host server I/O or workload performance, such as I/O throughput, for every virtual machine accessing the SAN; and
• any KPIs related to SAN/LUN capacity — look for capacity trends or shortages.

An administrator can ensure a clear view of the SAN’s health and take proactive measures to keep the SAN operating properly by implementing a regular review process and taking advantage of alerts and reporting features within the storage area network.

Furthermore, features and functionality designed to automate the SAN or mitigate storage disruptions can benefit SAN management. SANs that enable the use of policies for tasks such as provisioning and data protection, for example, can assist administrators in avoiding oversights and mistakes that could waste storage or jeopardize security. Similarly, features like native replication can help protect valuable data while allowing constant access to it.

Remote storage area network management is becoming increasingly important in SAN administration. This allows SANs to be built in remote locations outside of the main data center, or for a single SAN administrator to support one or more SANs from anywhere in the world. Remote SAN management necessitates a dependable network connection between the management tool (the administrator) and the SAN under management. The remote tool should be able to convey comprehensive SAN health details, such as the aforementioned KPIs, as well as support provisioning and launch diagnostics to assist in locating and eliminating potential SAN problems. SolarWinds Storage Resource Monitor, IntelliMagic Vision for SAN, and EG Innovations Infrastructure Monitoring are examples of popular remote SAN tools.

Conclusion

It is essential for any business to have access to timely and accurate information in order to maintain or ensure its expected results. It is also critical to ensure that this business information is properly managed and protected in order to deliver the expected results and allow the company to grow.