December 2000, Technology Corner
by Rob Hirschfeld

The Joys of Data Storage

There is little I can say to make data storage more exciting.  Storage is as exciting as cash sitting in a bank vault: you don’t worry until it is missing.  To most businesses, the data stored on their computers should be even more valuable than cash in the bank; unfortunately, many companies treat storage as an after-thought.

 

Businesses that treat storage seriously invest in a dedicated storage infrastructure.  There is a booming market for technologies whose sole purpose is to deliver enterprise class data storage.

 

Enterprise class data storage is one of the most expensive parts of a robust technology infrastructure.  These systems typically cost hundreds of thousands of dollars and are basically just farms of disk drives.  However, comparing a single disk drive to an enterprise storage system is like comparing a house to a military complex. 

 

The requirements for enterprise storage systems are orders of magnitude more demanding than those for the humble disk drives found in desktop computers.  The difference is not the drive mechanics, but way the drives are packaged to ensure that enterprise storage systems deliver incredible levels of reliability, availability, and scalability.

 

Reliability, Availability, and Scalability?

Reliability means that your data is always there.  Excepting natural disasters, the information stored in the system will exist even if it has multiple failures.  You should never loose data due to a system failure because information is stored redundantly on multiple disks within the equipment.  High-end enterprise storage offers the ability to duplicate your data in multiple geographic locations to even eliminate the risk of natural disasters.

 

Availability ensures that you can actually get to your data.  Typically, we expect enterprise storage to be available 99.999% of the time or better.  To achieve this level of availability, the system must have redundant ways to actually access the data.  If one part breaks access is not interrupted and technicians should be able to fix the part without turning off the overall system.

 

Scalability means that you can expand the system gracefully.  Enterprise storage must be able to grow as your needs grow and maintain performance during peak loads.  An important aspect of scalable storage is the ability to create virtual data spaces that far exceed the physical data and performance capability of individual drives.

 

Strong reliability, availability, and scalability form a solid foundation: without a solid foundation, no other part of your technology infrastructure can deliver a superior quality of service.

 

Clustering demands enterprise storage

Clustering of servers is the dominant driver for deployment of an enterprise storage system.  Clustering means that mission critical functions, like database and email processing, are delivered by redundant servers.  The redundancy allows individual servers to fail with minimal or no interruption to the business function.

 

In order for clustering to work, clustered servers must have access to a shared storage device.   When one server fails, the backup servers are able to immediately read the data that was being managed by the failed server.  This scenario, known as a “fail-over,” requires an enterprise storage system.

 

SAN vs. NAS

Within the world of enterprise storage, there are two dominate types of storage: storage area networks (SAN) and network attached storage (NAS).  The differences between SAN and NAS do not make exciting dinner conversation, but do play a role in how efficiently your business software runs.  The simple distinction is that a SAN is used to replace dedicated disk storage for servers while a NAS delivers a storage pool that can be easily shared within your network.

 

Both SAN and NAS vendors are introducing more cost effective solutions and also blurring the line between SAN and NAS solutions.  In general, NAS solutions have lower entry points suitable for bulk storage while SAN solutions are considered higher performing and better for clustering.  However, technology advances are changing the rules: high-end NAS can deliver clustering and some SAN vendors are committed to making SAN more affordable.

 

The Bottom Line

Enterprise storage solutions have finally become affordable enough that midrange businesses should start shopping for them.  Choosing the right SAN, NAS, or combination solution is a complex process that should be approached carefully.  I recommend getting multiple opinions because there is no one right way to deploy enterprise storage.

 

 

Sidebar: Enterprise Storage Vendors:

Xiotech, Network Appliance, EMC2, Compaq, Sun, IBM, StorageTek, MaxAttach, Quantum, Winchester, and MaxStore

 

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Originally appeared in Midrange Enterprise. Used with permission.