What Is a SAN? Storage Area Networks Explained

This topic reminds me of one of my favorite reality TV shows — Storage Wars. It’s a bunch of people scrambling to find treasures in abandoned storage units. SAN is a different kind of storage concept.

SAN is a high-speed network that connects servers to shared storage devices.

I’d say that there’s also some form of scrambling that goes on with SAN as servers fetch data from storage over the network.

The main difference between SAN and Storage Wars is that with SAN, there isn’t any guessing or gambling. If this doesn’t make sense yet, stick around a little bit longer.

A SAN runs on its own separate network. It reminds me of the one Christmas I visited the beautiful state of Oregon via train. I was thinking of a road trip, but that would mean worrying about emergency freeway closure due to black ice. Happens a lot there in the winter.

Trains are rarely impacted by (most) bad weather conditions. And because of that, it’s still the good old reliable means of transportation it was intended to be.

Now SANs are the electric trains of the internet. And their railway lines are fiber-optic cables.

This network isn’t the same as your regular internet or office network. It’s just an express lane for storage traffic. To keep everything moving fast, it avoids getting mixed up with the usual network traffic.

SAN doesn’t need to worry about emails or video calls. Instead, its only business is to transfer data. Because that’s its only concern, it can handle huge amounts of data without delays.

Every computer or network you interact with usually has several parts working together to deliver what you want. Here’s what you’ll find inside a SAN.

Host Bus Adapters (HBAs) and SAN Switches

HBAs are like the plug between the server and the storage devices in a SAN. They connect the two and make sure they speak the same language.

If these two don’t speak the same language, things could get messy really quickly.

It’s like ordering a 16-ounce vanilla chai latte (my favorite), and the barista is like:

“Here’s your 20-ounce Americano. Anything else?”

It could be an honest mistake. Or, maybe, they’re just not paying attention. Either way, it’s still frustrating. That’s the kind of conversation the server and the storage device might have without HBAs.

SAN switches are the traffic controllers of the SAN. Their main job here is to link servers and storage devices.

These guys make sure data moves through the right path without getting stuck. You can think of them like how traffic lights help prevent jams. The more switches you have, the better the network’s ability to handle large amounts of data without slowing down.

Storage Arrays

I learned about arrays when studying JavaScript. And I must confess that it took me a while to understand the whole concept. Surprisingly, they’re actually not as complicated as they may sound.

An array is just a storage for data. In web development, we call it a collection of items.

Now imagine a collection of hard drives or SSDs working together like a team. For sure, that’s one big storage space you’re looking at.

And because they work together, they are usually designed so they’re pretty reliable and offer great performance. But that’s not even the main point here.

With such teamwork, everything should work even if one drive fails. One drive goes down and another one shows up, like:

“Hey buddy, you can get some rest. I’ll cover your shift.”

That way, your data stays safe and available no matter what. Now I hope you understand why enterprise businesses like Amazon.com rarely get any downtime.

Cabling (Fiber-Optic or Ethernet)

The cabling is what physically connects everything in a SAN. It’s like roads connecting different cities.

It can be either fiber-optic or Ethernet.

We learned earlier that fiber-optic cables are usually super-fast. But what I didn’t tell you is that they’re also expensive. Don’t let that put you off, though. It’s completely worth the investment if you go for it.

So to cut costs, some providers opt for Ethernet cables. But they’re way slower than fiber-optic ones. It’s up to you to decide if you’d rather have a high-speed connection at a higher price or slower speeds at a lower price.

You’ve discovered what components make up SAN. Now you’ll see how they are designed, organized, and connected to work together.

Block-Level Storage

You already saw that SAN loves the block. This means that a server can access individual chunks of data. And by handing over data individually, the delivery is usually way faster.

All along, the server gets tricked into thinking that the SAN storage is directly connected to it. In reality, the storage itself could be sitting miles away, minding its own business.

I want you to think of Walmart as an example.

Imagine a situation where you’re told to fetch cat litter from this popular retail outlet. You’re given two options: go to their warehouse and shift through a bunch of containers to find the cat litter, or head straight to aisle J10 and pick it up.

What would you choose? I bet I can guess your answer, unless you’ve got way too much time on your hands. And even if you do, I doubt that’s how you want to spend it.

Heading straight to aisle J10 is the answer. Why? Because you get the cat litter served to you as a single block, not the entire shipping container (or whatever packaging it’s shipped in).

Types of SAN Architectures

There are different types of SAN architectures, each with its pros and cons.

• Fibre Channel (FC) SANs use super-fast fiber-optic cables and is known for high speeds, low latency, and rock-solid reliability. If we’re talking in terms of express lanes for data, this is the premium version. However, it can be pricey and complex to set up.
• iSCSI SANs are affordable because they run over standard Ethernet networks. Yes, they may not be as fast as Fibre Channel SANs, but they’re easier to manage and cheaper.
• Fibre Channel over Ethernet (FCoE) blends the best of both worlds. It’s more like a hybrid version of FC and iSCI SANs. It allows Fibre Channel protocols to run over regular Ethernet networks, so you get the speed of Fibre Channel with the flexibility of Ethernet.

The SAN architecture for you will probably come down to your specific needs and budget.

Logical Unit Numbers (LUNs)

These are basically labels for a chunk of storage in the SAN. It keeps everything organized. It’s also fair to say that it’s responsible for managing storage across multiple servers.

For example, you could assign LUN I to one server’s database and LUN II to a virtual machine on another server. This way, system admins can split up the available storage and allocate it to different servers as needed.

This approach makes sure that each storage unit gets exactly what it needs to do what it’s meant to.

SAN offers so many benefits, some of which you might’ve already learned about if you’ve made it this far in this article. Here’s a recap.

• Centralized Storage: Instead of managing separate hard drives on individual servers, all the data sits in a shared storage pool. That means you can access everything you want from one place. This setup makes it especially easier to handle backups, replication, and disaster recovery. You can, for example, schedule automatic backups for all your systems from a single dashboard. Without such a system, you’d have to configure each server individually.
• High Scalability: SANs can grow with your business. Say you want to increase your data. In that case, you don’t have to replace entire systems. Instead, you simply add more storage arrays without interrupting any running applications, and you’re all set! It’s like adding more shelves to a library without temporarily closing it down.
• Improved Performance: You’ve seen that SANs offer much faster data access than traditional storage setups. This is especially important for applications that need to process a lot of data quickly. A good example here would be a business that runs a large eCommerce site. It needs fast access to orders, or customers won’t hesitate to shop elsewhere.
• Data Redundancy and Reliability: Many SANs use Redundant Array of Independent Disks (RAID), a technology that spreads data across multiple drives. If one drive fails, the system keeps working because other drives hold copies of the same data. With such a setup in place, data loss and downtime are the least of your worries. Another helpful feature is hot-swappable drives. What this means is that you can replace failing disks without turning off the system. For businesses that can’t afford even a single minute of downtime, this is a lifesaver.
• Increased Flexibility: With a SAN, you can dynamically allocate storage across multiple servers. You just need to find out what each server needs. For instance, if a server hosting a database suddenly needs more space, you can assign additional storage from the SAN without physically moving anything. This flexibility is perfect for businesses with changing workloads.
• Disaster Recovery: SANs can replicate data to remote locations. If something goes wrong, your data remains safe and accessible from the backup site. A bank, for example, can use SAN replication to copy all transactions to a secondary data center in real time. So let’s say you’ve called the bank to complain about that one transaction you have no idea where it came from. If the main center is down, the bank simply switches over to the backup site. And there won’t be any downtime at any point throughout this process.

SAN’s benefits reach far and wide. If you’re looking for better flexibility or scalability, you should consider it.

SAN fits many different roles in real life. These are just a few examples.

Virtualization Environments

Ever heard about virtual machines in web hosting? These are different machines running on a single physical server. And SANs are very important here.

Here’s the thing: virtual machines need shared, centralized storage in order to move seamlessly between physical servers without losing access to their data.

That’s precisely where SAN comes in. It provides the high-speed, low-latency connections required to manage these virtual machines. So if one server hosting VMs fails, another can pick up the workload.

Enterprise Data Centers

By “enterprise data centers,” I mean large-scale facilities that store, process, and manage huge amounts of data. A good example is Amazon Web Services.

SANs act as the backbone of these large-scale storage systems. It makes sure that databases, virtual machines, and important business applications are working as they should.

High-Performance Computing (HPC)

I know you’ve watched a live weather broadcast before. But have you ever paused for a second to ask yourself where that live data comes from?

There has to be some form of a high-performance computer somewhere processing this data in real time and displaying it to the public. And you know what drives such a computer? SANs.

The weather channel is just one example. Think of any scenario where you may need to process data in real time. From scientific research and sports data to financial modeling, the list is endless.

Backup and Archiving

You’ll also find SANs in powerful backup and archiving systems. I’m talking about the kind of environment where you need to store and access large amounts of data.

For instance, healthcare providers use SANs to store patient records securely. That explains why your doctor can pull your data from the system just by asking you a few questions about yourself.

There’s also a side of SAN that’s not so rosy. I believe knowing both sides can help prepare you for any challenges along the way.

Cost

Setting up a SAN costs a lot of money. You should expect to spend even more if you opt for the fiber-optic version. The cost covers things like HBAs, switches, and storage arrays. I hope you now understand why SANs are more suitable for organizations with large-scale storage needs.

Complexity

Managing a SAN isn’t that simple. That’s because it comes with specialized hardware, protocols, and software. It’s not the kind of technology you can master with a 30-minute crash course on YouTube. Don’t get me wrong, though; I’m not saying it’s impossible.

Also, you really need to understand how to configure and optimize the system properly. Once that’s out of the way, you’ll also need to learn how to troubleshoot SAN issues.

Power and Space Requirements

We’re talking about big machines, not just laptop-sized ones. And these machines need a lot of power to run. Power aside, they need space.

In data centers, for instance, companies spend thousands of dollars on racks and cable management systems alone to keep everything organized. This might not be the best option if you don’t have such a budget.

Risk of Single Points of Failure

If not configured correctly, a single point of failure could be all it takes to bring the entire system down. Remember when we talked about the different components of SANs?

They work together as a team. But because there’s so much teamwork involved, a serious injury to one star player could impact the whole team. Does that make sense? Take a switch failure, for example. This isn’t just a small storage device that you can easily replace. Nope!

We’re talking about the traffic lights of the entire system. And what happens when traffic lights suddenly stop working? Accidents are bound to happen. There’ll be injuries or, even worse, casualties.

When it comes to storage, SAN, NAS, and DAS each do things a little differently. I’ll explain.

When to Use Each

The table below sums up different scenarios when SAN, NAS, or DAS would be the best choice.

Small business owners with little infrastructure are best off with a DAS, whereas an enterprise with more complex virtualization needs is better suited to using a SAN.

Don’t let what I told you about SAN scare you. After all, someone has to set it up, right?

Planning Your SAN

SAN has many strengths, so it’s important that you know exactly why you need it in the first place. Start by figuring out how much storage you need now. Once that’s out of the way, think about how much storage you’ll need down the road.

You don’t need actual numbers; estimates should do just fine. Then, think about performance. What kind of database do you plan on running? Will it need quick access?

Or do you just want something that can store lots of files with some room to grow? It’s also a good idea to build in some redundancy so you’re covered if something fails.

Selecting the Right Components

Let’s talk about components one more time. They’re not the kind of stuff you just plug into your system and watch the magic happen. How you select these components will determine what kind of environment they’ll create.

The most important components here are HBAs, switches, storage arrays, and cables. It’s unlikely that you won’t need them. You’ll want to make sure your HBAs match your servers. Your switches should also be able to handle the amount of data flowing through.

The kind of storage you opt for matters.

If you’re on a budget, you can mix spinning disks and SSDs. That should be good enough to get the job done.

As for cables, fiber-optic is great for speed, but it’s going to cost you a lot of money to set up. The other option is to use Ethernet. It’s easier to set up and less expensive, but not as fast as fiber-optic.

Once you have everything, it’s time to set it up. Here’s an overview of the process:

1. Install the HBAs into your servers.
2. Connect them to the storage arrays using the switches and cables.
3. Configure your SAN software to manage how storage is allocated.

Speaking of storage management, remember to use LUNs. They let you assign specific chunks of storage to different servers.

Managing and Monitoring the SAN

Once your SAN is up and running, you should keep an eye on the whole system. To make things easier, consider using management tools.

You’ve got plenty of options:

• Dell EMC Unisphere: Best for managing Dell storage arrays like VMAX and PowerStore. I would recommend it for organizations already using Dell EMC infrastructure.
• NetApp OnCommand Insight: Best for monitoring and managing both SAN and hybrid cloud environments. That makes it a great alternative for companies with a mix of on-premises and cloud storage.
• HPE StoreOnce Catalyst: Best for backup management and data reduction in SAN environments. This is the kind of system you need for disaster recovery.
• SolarWinds Storage Resource Monitor (SRM): Keeps an eye on multi-vendor storage environments (SANs included). I’d go in this direction if I wanted to monitor many different storage systems from different vendors in one place.

My tip for choosing a management tool is to read real user reviews online and test out the platform’s customer support — send them a message and see how fast they respond.

Implementing Security Protocols

Security is a big deal with SANs. And you know why? They handle a lot of important stuff.

Make sure you’ve got controlled access. That way, only authorized users can connect to the network. Don’t forget about encryption. You need it, especially for data in transit.

Also, remember to monitor the network traffic for anything unusual. The sooner you catch these threats, the safer your systems will be.

Let’s talk about the trendy stuff. And no, I’m not talking about fashion.

Software-Defined Storage (SDS)

SDS is making storage do things we didn’t even know it could. Gone are the days when we only relied on hardware for storage management. Today, you can manage storage resources through software.

To begin with, that means more control. Secondly, it means you can mix and match different kinds of hardware, and they’ll get along.

NVMe over Fabrics (NVMe-oF)

You’ve heard of NVMe, but what about NVMe-oF? NVMe-oF is a type of technology that extends the high-speed nature of NVMe across a network. Add this technology to the already fast SAN (especially where fiber optics are involved), and you’ll get lightning speeds.

You’ll find NVMe-oF in environments that deal with data-heavy applications. Good examples include data analytics or machine learning.

Hybrid SAN Solutions

A lot of organizations are adopting hybrid SANs. Here, you combine spinning disks and SSDs to get the best of both worlds.

Hybrid SAN solutions combine both SSD and HDD technology.

SSDs, on the one hand, provide fast storage for critical data. That means you can also access this data faster.

Then spinning disks (traditional hard drives) come in to store the less important stuff. They’ll also save you money because they’re way cheaper than SSDs.

Cloud-Connected SANs

Some SANs are now integrating with cloud storage to create yet another hybrid system. By using SANs with cloud storage, you can store data locally for fast access. The cloud, on the other hand, comes in for backups or disaster recovery.

It’s actually a smart way to get the benefits of both on-premises and the cloud. The best part is that you don’t have to commit to one or the other.

That was quite a lesson, wasn’t it? You’ve probably heard enough, so I’ll keep it short and sweet here.

SAN is not a storage unit. It’s just a network that links storage devices to servers.

So who really needs SAN? The answer is simple: any business that handles mission-critical data and wants a sprinkle of speed, scalability, and reliability.