In case you stumbled on the title but have no idea what it means. Let’s start with the fact that DAS, NAS, and SAN are abbreviations for different storage technologies.
- DAS – Direct Attached Storage
- NAS – Network Attached Storage
- SAN – Storage Area Network
Every organization needs storage, as they need somewhere to store their data. Preferably this is done reliably, securely, and efficiently as nowadays, organizations can easily be crippled if they lose their data.
In this blog post, I’ll cover the different storage options mentioned above and list some pros and cons, so you can decide which one better suits your needs
Direct Attached Storage (DAS)
Direct Attached Storage is probably the easiest of the bunch, as the name tells a lot about how it works. DAS is a type of storage directly attached to a device (for example, a server). Of course, the most common one is one we all know, a USB hard drive is a perfect example of a DAS storage device.
DAS storage solutions are identified by the fact that no network connectivity is involved. This might make connecting multiple hosts (when speaking about virtualization) to a single DAS device more difficult. Still, some DAS storage arrays would have multiple SAS (Serial Attached SCSI) ports. Allowing some form of redundancy and scalability.
Pros
- Low(er) latency as no networking equipment is introducing additional hops
- Cheap(er) as less equipment is required
- Easier to use and maintain
Cons
- Scalability is limited due to the number of interfaces
- No external accessibility, sharing storage or remote access is limited
Network Attached Storage (NAS)
Network Attached Storage’s trademark is also part of the name, as it is a file-level storage solution connected to a network. This connectivity is also its biggest strength, as it can generally be accessed from all devices that are part of the same network.
Well-known NAS devices come (for both personal and professional usage) from brands such as Synology and QNAP. At the same time, enterprises rely more on devices from vendors such as HPE, DELL, and Pure Storage.
Based on your performance and/or capacity needs, these devices can be equipped with either SSDs or HDDs (or a hybrid format), typically part of a RAID array to offer some form of local redundancy. In addition, a different level of redundancy can sometimes be achieved by creating a cluster of these NAS devices, making it entirely invisible for connecting devices to which NAS they are communicating. Accessing the storage on these NAS devices happens via one or multiple storage protocols, SMB (Server Message Block) or NFS (Network File System), each of these protocols has its pros and cons.
Pros
- NAS solutions are highly flexible. Some can even run virtual machines
- Different availability and redundancy options depend on the make and model
- Accessible from all devices participating in the same network
Cons
- Performance is impacted by the chosen storage (SSD or HDD) and networking equipment
- Sizing a NAS can be difficult, as you need to calculate up front how much storage is required (including compression and deduplication)
Storage Area Network (SAN)
A Storage Area Network is a network dedicated to storage. Its purpose is to transfer data between one or multiple storage arrays, servers or hosts. For performance purposes, it’s separated from the LAN and commonly uses fiber channel to provide connectivity.
The infrastructure typically holds one or multiple SAN switches, which provide connectivity between the storage array via one or multiple controllers for redundancy.
As seen in the image below, a SAN holds more components and introduces more complexity.
To avoid conflicts in terms of accessibility, fiber channel zoning is commonly applied. The most straightforward comparison would be a firewall rule where Host A can only communicate with Storage Array ports A and B.
Though there are different options depending on your budget and the capabilities you are after, don’t expect to use one at home unless you need it for business/professional purpose (and don’t forget the power consumption and noise levels).
In random order, the capabilities you could be looking for are deduplication, compression, storage replication, clustering, or storage snapshots. While this list isn’t conclusive, the same approach applies when buying a car. The more options you’re after, the more expensive it gets.
Popular and well-known SAN brands and models are Pure Storage (with FlashArray and FlashBlade, Dell EMC (PowerStore and PowerVault), HPE (with 3PAR and Nimble), and last but not least: NetApp with their different solutions.
Whichever you choose, make sure to do your homework to guarantee you’re buying the right solution.
Pros
- Separate infrastructure, reduces the consumption of the LAN
- Higher performance due to dedicated components for providing storage
- Highly available and scalable as components can easily be added
Cons
- Higher cost due to enterprise-grade equipment
- Higher complexity due to the number of components involved
Closing
I hope this blog post clarified some of the key differences between DAS, NAS, and SAN storage technologies. But, of course, there is no right or wrong, as each one of these solutions has its use.
Something worth keeping in mind is that some backup solutions offer native integrations with storage solutions, allowing direct communication and offloading specific tasks such as creating array-based snapshots and using these to create a backup, reducing the load on the virtualization platform.
Vembu BDRSuite is a comprehensive and flexible Backup and Disaster Recovery solution which supports all these types of storages – DAS, NAS, SAN and even object storages on cloud. Plan to protect your business critical data today by evaluating a free trial
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