The DAS Alternative?

There’s a lot of discussion about the resurgence of DAS and alternatives to SAN and NAS; whether these be virtual appliances, clustering storage, object or just plan old direct-attached-disk; all of these are seen as ways to replace the expensive network storage be it SAN or NAS attached.

But is this actually important or even especially new? It is certainly the case that the software vendors such as Microsoft and Oracle would like a piece of the action but we also have new players coming in via the virtualisation space.

Personally I see it just as another evolution in the realm of Networked Shared Storage; SAN, NAS and Clustered-Storage. The clustered storage will generally be built around commodity disk but it will not be exclusively so; it may be accessed in a variety of ways, clustered file-systems such as StorNext, GPFS and Gluster will all provide a block-level access but you can also throw in object technologies such as Caringo and you may still decide to access via the traditional NAS protocols.

There are certainly some interesting possibilities where block and file access could be provided to the same data; build yourself a storage-cluster and add in client nodes which see the storage as ‘local filesystems’ but also have remote access via NAS/CIFS or even object.

But is this really a resurgence of DAS? Not really, it’s still networked storage but just different. Existing SAN infrastructures can be leveraged to provide access to the physical bits (the rise of SSDs means no more storage is rust!). We simply have a new (actually old) tool in the box.

And it just reflects what we already know; Storage is Software…