When to choose between SAN, NAS and DAS for your storage needs

Today’s datacenters are growing at a fast pace and the need for storage is at its greatest demand ever, but understanding what storage platform you need is just as important as the storage itself.

A real world example is a client needs additional storage capacity for an existing file server, adding a DAS (Direct Attached Storage) can allow you to add drives and capacity to an existing server’s storage pool and is by far the cheapest option in terms of storage growth for that platform. With a DAS, the enclosure is typically designed to support one node at a time. It is not able to share disk resources to other connected servers if a second server can connect thus limiting this as an expansion for network resources.

However, there are situations where a DAS is not the best option, such as adding storage to multiple servers at the same time. This is where a SAN (Storage Area Network) can be considered as a solution.  A SAN allows a pool of disks to be segmented and shared over a network as raw disks (LUN) to one or more targets (Servers).  This type of storage is very flexible but can be very pricy and usually proprietary which means an upgrade could be a complete replacement.  These types of storage are usually allocated to clusters in the form of CSV (Cluster Shared Volumes). They can allow multiple members access to the storage but it elects the node that is able to manage the data at any given moment.  A good example would be a cluster running SQL servers. When a node goes down, another node picks up the data where it was left giving the users uninterrupted access.  Another example is a Active-Active cluster such as a Hyper-V environment. In this scenario all nodes have access to all storage at the same time to allow multiple servers to process data in a shared capacity and allow unlimited growth potential within the nodes.

The last type of storage is called a NAS (Network-Attached Storage). This has some unique advantages as it is storage that is accessible over the network as a mountable drive storage. It can be treated similar to a file server in that users can access, change permissions and map to the storage. It may even have some low level capabilities to provide raw access to a LUN similar to a SAN. These devices are relatively inexpensive and can provide different RAID options for drive redundancy and Disaster Recovery.  However, these devices are typically low powered and the feature set is not typically feature rich. They do provide fast access to direct data over the network. Their real advantage is in the use of backups.  Typically when companies performed backups in the past, tapes were used and were very slow in recovery of data. However, these newer devices allow backups and recovery of data if it is used as a backup software target. They can operate at a fraction of the cost of tape and are multiple times faster making this a prime device as a backup media for local data.

This article reviews several different uses for these storage devices and discusses its real world uses. If you have questions or would like help with your next storage project, Raffa is the perfect choice to help match the best storage options for your organizational needs.

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Post by Jason Tonks


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