SAN vs. NAS vs. DAS Storage: Which One You Choose

In today’s information-centric world, storage is one of the most important things for enterprises. As the data volumes continue to increase exponentially, the importance of choosing the right storage systems to fulfill the storage and access demands also rises.

In general, enterprises consider three options when looking for storage solutions. These are SAN (Storage Area Network), NAS (Network Attached Storage), and DAS (Direct Attached Storage).

Most enterprises that are looking to modernize their infrastructure go with a hybrid cloud approach, where a combination of one or more of these options is adopted.

This article discusses the difference between these enterprise storage devices and how businesses can choose the right one.

What Is SAN?

A storage area network (SAN) is network or sub-network that interconnects several servers or computers to logical disk units (LUNs). LUNs are blocks from pools of shared storage that work as logical disks to servers or PCs. SAN uses protocols like iSCSI, SCSI, and fiber channel.

SAN is highly popular in enterprise computing to consolidate storage. Earlier, the servers used internal disks as a block device which restricted scaling of storage to the individual server. However, SAN provides block devices across the network, so that host servers have control over their file systems.

Unified SAN Storage

Due to improvements in disk storage technologies and the growth of Ethernet and TCP/IP, unified SAN solutions are also available. Unified SAN storage supports both SAN and NAS features. It is compatible with several different protocols like iSCSI, FC, CIFS, S3, and NFS. These solutions combine SAN and NAS solutions.

Examples include FAS2720 AND FAS2750 Express Pack products by NetApp. FAS2720 systems are designed with 12 internal NL-SAS drives and offer high capacity at low cost. FAS2750 systems can have 24 internal RPM SAS drives and provide high performance at optimal price.

FAS (fabric-attached storage) storage solutions are easy to deploy for operations and support cloud integration by small and mid-sized businesses.

These can support high volume unstructured data from medical imaging, media, and so on. There are no downtime issues during software or service storage upgrades. NetApp offers FAS series with SSDs as different models of All Flash FAS (AFF) systems.

Advantages of SAN

There are several advantages of SAN for enterprise-level workloads.

High availability: As SAN is a mesh of interconnected storage devices and computers on the network, any disruption in one path does not cause communication failure between the storage device and host. SAN storage remains accessible to the workload through other paths.
High-speed performance: In SAN, the storage processing for the connected devices happens on a separate network and not on the LAN (local area network). This reduces storage traffic congestion and frees up bandwidth on LAN.

Hence, dedicated SAN offers better storage tasks performance than other storage options. For example, E2800 series by NetApp, the global cloud-led, data-centric software company, is optimized for high performance and data-intensive computing.
Advanced management: SAN supports several features that can be applied to all its storage resources. The features include data deduplication, data encryption, storage replication, and more to improve capacity and security.
Scalability: A SAN can comprise multiple storage devices/ storage arrays and host servers. It even supports the addition of new storage and host servers to such large deployments whenever business requirements arise.

Disadvantages of SAN

IT teams need to consider the following disadvantages before deploying or upgrading SAN.

Costs: The costs of infrastructure set up to support SAN and ongoing maintenance are so high that only large organizations can afford them. The storage pool is costly even though it is shared among servers, and it takes time to get a return on investment (ROI).
Complexity: SAN implementation, especially traditionally, is complex and needs careful monitoring. SAN maintenance requires a trained in-house IT team or expert third-party professionals. This need makes it difficult to justify the implementation of SAN on a smaller scale.
Management: Managing features such as LUN (logical unit number) mapping or zoning are time consuming tasks for any organization. However, they cannot be avoided due to compliance requirements.

What Is NAS?

Network-attached Storage (NAS) is a file-level computer data storage architecture that provides network users and other client groups a single access point for storage.

It uses protocols like SMB and NFS so that clients can attach to NAS. The NAS works as a network node with in-built security and fault tolerance to communicate with other network devices.

It is generally used for supporting shared applications like email systems, data logging, business analytics, engineering software builds, and so on. The system size varies depending on the scale, speed, and budget.

Advantages of NAS

NAS systems are simple to operate, waste less space, and do not require much involvement of IT teams. NAS offers the following advantages that are highly useful for small businesses:

Scalability: NAS ensures that the storage capacity can be simply increased by adding new hard drives or NAS devices. Drives are hot-swappable. That is, there is no need to shut down the entire network or replace/ upgrade existing servers. It is a cost-effective method that comes with secure data backup.
Performance: NAS offers certain performance advantages by removing file serving responsibilities from other networked devices to serve files faster. However, unlike SAN, it is connected to LAN.
Accessibility: With a centralized storage system, NAS makes it easy for network devices to access data. It can be accessed via a network connection from anywhere at any time. This means that users can work on joint projects through features like file sharing and collaboration with others. The operating systems can also be different, like Windows, MacOS, or Unix.

Disadvantages of NAS

Increased traffic: NAS is network-dependent, and LAN is responsible for transferring file data from one location to another in the form of data packets. Due to traffic congestion, the data packets may be delayed or sent to terminals out of order and even affect other users. So, NAS is not suitable for applications that require intensive data transfer operations.
Unsuitable for large networks: If too many clients join the network and access the NAS file system, performance can degrade quickly and lead to user frustration. This is because protocols like NFS and SMB are not quick enough. Also, the bandwidth of the enterprise network and the availability of other resources limit the NAS system.
Security and availability: You can only get on-site data backup with NAS, which puts the data at high loss risk in cases of cyberattacks, natural disasters, or manual errors. Unlike SAN, NAS can become a single point of failure in the network as it cannot be configured to provide alternative paths in such instances.

What Is DAS?

Direct attached Storage (DAS) is a digital storage that is connected to the system (a PC, workstation, or a server) directly via an internal cable. Examples of storage devices include hard drives, solid state drives, optical disk drives, and so on.

The system has multiple hard disk drives in one enclosure without any network device like a switch or router. It can have various types of interfaces connected to a server like SCSI, HBA, SATA, IDE/ATA, Fibre, etc. Separate disk drives in one server are attached directly or through these interfaces to external drives.

Advantages of DAS

Easy implementation: DAS solutions are easily available and simple to configure, set up, and access. Internal DAS is preinstalled in a new server or computer and is instantly ready to use. External DAS is a plug-and-play solution that needs to be attached to a USB port for use.
Affordable: DAS does not require software or hardware for running and managing the storage system, making it a cheaper option than SAN and NAS. You only have to pay for drive enclosures and disk drives needed during setup.
Performance: DAS gives fast data access and enables high-performance I/O operations as the storage is connected to the host machine directly. Also, there are no network latency or bandwidth issues as the system is not connected to the network.

Disadvantages of DAS

Limited accessibility: DAS can only be accessed by applications running on the server or computer that DAS is connected to. It does not share storage resources with different servers or users via network hardware or related operating environment. This limits collaboration as the storage cannot be accessed by other groups on the network.
Scalability: DAS is difficult to scale as storage capacity cannot be expanded. Factors like the capacity of external DAS devices, the number of internal drive bays, and the availability of external ports on individual devices limit the available options.
Lack of central management: DAS has no mechanisms for backups and central management. As the network grows, it becomes challenging to ensure the availability and security of DAS storage. In addition, it becomes difficult to manage the local copies.

SAN vs NAS vs DAS Storage: What’s the Difference

SAN, NAS, and DAS have the same purpose- storage and they complement each other. However, they are different in terms of original intent, path, and outcome.

Storage mechanism:
The main difference between SAN, NAS, and DAS storage is the storage mechanism. SAN uses block storage, NAS uses shared files, and DAS uses hard-drive storage with sectors. The storage is shareable and scalable in terms of performance and capacity for both SAN and NAS, but not DAS or server-centric storage architecture.
Data transmission:
The technologies for data transmission are also different. SAN deployment types are IP SAN and fibre channel SAN, NAS uses Ethernet and TCP/IP, and DAS uses IDE/SCSI.
Advanced features:
SAN or information-centric architecture offers low latency and high throughput. It works in highly resilient environments and has features like synchronous replication.

NAS offers features like replication, thin provisioning, and snapshots. It is highly flexible and compatible with various operating systems. It can abstract storage management from the server and handle unstructured data like video, audio, text files, and so on.

DAS is less expensive than SAN/ NAS and does not have features like snapshots.
Storage devices and servers:
In SAN, the storage devices are managed centrally and can be shared between several compute systems. They can exist independently of the servers.

In NAS, the storage devices are connected to the network directly for file sharing. It has a dedicated OS for file serving that uses standard protocols such as FTP, NFS, and CIFS.

In DAS, there are limited storage devices for each server and they only exist in relation to these servers. It uses the host’s OS for implementing data backup, management, and other tasks.

	SAN	NAS	DAS
Type of storage	Blocks	Shared files	Sectors
Transmission of data	Fiber Channel	Ethernet, TCP/IP	IDE/SCSI
Speed	5-10 ms	20-50 ms	5-10 ms
Complexity	High	Moderate	Easy
Mode of Access	Servers	Clients or Servers	Clients or Servers
Capacity	> 10^12 bytes	10^9-10^12 bytes	10^9 bytes
Usage	Application data	Unstructured, Shared data	OS

Which One Should You Choose: SAN vs NAS vs DAS

The three main options for enterprise data storage systems come with different advantages and disadvantages. You can also choose unified SAN solutions to obtain maximum benefits from consolidation of SAN and NAS storage solutions. Unified SAN solutions can also work well for individual SAN and NAS cases.

An organization needs to decide which storage system works best based on storage capacity, backup, accessibility (including remote), disaster recovery, and scalability needs. It also depends on whether you have the budget and adequate IT resources to manage the storage system.

Scalability: You need to analyze the amount of data to be stored in the coming years.
Capacity: This value is based on the amount of data that needs to be stored.
IT Staff: It is crucial to know the IT staff and resource availability beforehand to manage your storage system.
Performance: The performance requirements will vary on the frequency and number of employees who need to collaborate on or share/access files from different locations.
Reliability: You must know the options you have during downtime. Also, you need to understand which files, applications, and data are critical for your business. Proper planning is important for file backup and recovery.
Budget: Depending on your requirements availability of funds, you need to figure out what your optimum spending would be.
Usage: DAS is useful for small businesses that have limited IT and financial resources. However, choose SAN or NAS if you want better storage capacity and performance.

SAN Use Cases

SAN has features like speed, flexibility, sharing, and reliability to support complex mission-critical applications at enterprises, data centers, or virtual computing environments. However, it need not be used in a small to midsize organization with limited IT staff and budget. Its main uses are:

Virtualization

SAN supports the quick transfer of multiple I/O streams between virtualization hosts and thousands of virtual machines (VMs). As a result, it can meet the high-performance needs of virtualized environments that run many operating systems (OS) and applications.

DBMS (Database Management Systems)

SAN is a good choice for enterprise databases and e-commerce websites. It offers low latency and high I/O processing speeds, making it suitable for handling large amounts of transactions per second. In addition, it is reliable and scalable, which enables it to support mission-critical workloads.

For instance, NetApp E2800 series is a great way for companies of any size to streamline their IT infrastructure with a pay-as-you-grow pricing model. The hybrid flash storage system has simple configuration and offers features like high throughput, high I/O per second, and so on.

It is compatible with several host operating systems such as IBM AIX, VMware ESX, Microsoft Windows server, Apple macOS, Oracle Solaris, CentOS Linux, Ubuntu Linux, etc.

NAS Use Cases

NAS is a good option for SMBs and other organizations that need a flexible, reliable, and scalable storage system that offers network-based file serving and sharing.

But if you wish to use server-class devices to transfer block-level data that is supported by a fibre channel connection, NAS can cause issues with data transfer. Some use cases are:

File Storage and Sharing

NAS is the preferred choice when any organization needs centralized file storage and sharing solutions regardless of its size. You can consolidate several file servers on a single NAS device for reducing space wastage, greater simplicity, and easy management. It also enables collaboration.

Big Data

NAS can store large volumes of unstructured data from IoT devices, video surveillance recordings, and so on. It is easy to scale and can be used for processing intelligent data services, ETL (extract, transform, load) operations, analytics, and so on.

DAS Use Cases

DAS is a great low-maintenance, low-cost storage solution for businesses that do not have IT support for complex systems. However, it is not a good choice for businesses that are growing quickly and need collaboration features.

A Cost-Effective Simple Storage Solution

DAS works well for small organizations as it needs only the storage device and optional drive enclosures for setup on individual systems. It can share data locally, even though it cannot connect to the network. It is a good storage option when you do not have enough IT support or budget.

Conclusion

The three storage solutions- SAN, NAS, and DAS, complement each other. While DAS systems are used by small organizations, SAN and NAS solutions are used for high performance and scalability.

NetApp offers a host of reliable storage solutions that can be used in various industry sectors like business services, healthcare, financial services, automotive, media, retailers, insurance, and so on.

It would help if you explored different SAN and NAS solutions available that fit your requirements before deciding which NetApp products you wish to choose.