Friday, November 28, 2008

INFORMATION - Consolidation

MARKET – OPPORTUNITY – Problem needing a solution

The market for consolidate storage is fairly well understood. There are generally two different types of access to storage; block and file. The block level access is performed by devices like the DS3000/DS4000/DS5000. The storage looks and feels like direct attached storage, and the performance characteristic requirements are usually more demanding. File level access requires a server (or appliance) between the storage and the servers accessing the storage via NFS or CIFS. This type of storage is usually less demanding as far as performance is required, but usually has the requirement of sharing access to files for multiple servers. This is the environment that spawned the NAS industry. Originally the NAS storage server was a standard server with lots of direct attached storage. This model is alive and well in many customer environments.

Problems arise with the standard server approach when other applications start to run on the servers that are providing NAS storage to other systems. Many times server maintenance, application problems, or hardware problems can cause wide outages (to many other servers besides the file server). As the industry matured, the file server role became separated, and the idea of storage consolidate became split between block-level and network-attached storage.

Some of the NAS vendors, noticing that benefits of storage consolidation was being diluted, decided to offer block-level access to their NAS storage. Although this seems like a good thing, the differences in storage access methodology leads to several inefficiencies, and performance suffers. Remember, when consolidating storage, performance is very important because more and more servers (and hence more and more applications) are relying on fewer storage subsystems. This means that slower performance can impact many application (not just one server), and have a greater impact on the business as a whole.

Another approach is to consolidate the storage onto a storage subsystem, and have a “NAS GATEWAY” offer NAS access to the consolidated storage. This is similar to having another server on the SAN, but the application is to provide file level access to other servers. So then the question is asked; what is the best way to implement a NAS Gateway? This question has a variety of answers, all depending on the balance of cost, effort, and support. I will go through a few options, and try to point out the differences. First, I would like to present a diagram that represents the configuration we’re discussing. There is a corporate Fibre Channel SAN with servers attached to storage and a tape library. Also attached to this SAN is the NAS Gateway, which offers up NAS storage to other servers over the corporate network. All options below could generally fall under this same configuration.

Information provided by:

James Latham
Product Specialist

Storage Solutions Engenio Storage Group

LSI Logic Corporation

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