Not All Network Attached Storage Is Created Equal
by Steve Rogers
westworldproductions.com
This article is the first in a two-part series. The second part will appear in the March issue of SMS.
The Network Attached Storage (NAS) market has come into the mainstream for network administrators and IT managers as another technology to consider when buying and deploying storage resources. As with any new technology, some major misconceptions have also emerged. To date, there is not a widespread understanding of the various classes of NAS solutions available. The reality is that NAS product offerings span the spectrum from sub-$1000 solutions with minimal functionality to enterprise-class products that cost hundreds of thousands of dollars. Simply put, all NAS solutions are not created equal. This article will attempt to clarify many of the NAS misconceptions with a view of where NAS technology fits, what customer storage problems it solves, a new method of evaluating NAS products, and a discussion of how NAS can dramatically lower the total cost of ownership for network storage.
NAS Market Overview
The NAS market is one of the hottest segments of the storage industry with robust growth predicted in the coming years:
IDC projects NAS will experience 66 percent annual growth rate over the next three years becoming a $6.5 billion market by 2003, up from around $850 million in 1999.
The market for workgroup-class NAS solutions will reach $1.31 billion by next year, according to Dataquest.
The NAS market is unique because it can best be viewed outside the traditional "corporate-centric" view of storage in that it brings a user-centric model to the storage industry, as much of the data stored on NAS servers is outside the traditional corporate "enterprise" realm. Often referred to as NAS servers, these devices can more accurately be characterized as providing "file services" rather then being a "file server." A NAS device does not have to be a server to serve files, but it does have to be managed, either separately or preferably by the server environment it is integrating into. If used to serve files in an open client environment, the management effort required on a NAS device is related to client turnover (adding and deleting accounts) and the maintenance of related file access needs.
Because of the simplicity in installation, operation, and administration, NAS devices have gained wide appeal in small businesses, fast growing Internet operations, and other sites that lack traditional IT staffs. A vast range of small to medium-sized businesses operate every day with a broad spectrum of storage intensive applications, with law offices, accounting firms, schools, libraries, and government entities requiring applications such as publishing, printing, video file services, audio file services, POS transaction-based, and records-retention to name a few. And all of these diverse businesses can benefit from deploying NAS devices.
The NAS market has generally been viewed horizontally as all encompassing, as storage is needed in just about every application; but similar to general purpose application servers, there are clear demarcations. The most common-and useful-stratification is a three-tiered level approach with entry level, midrange, and high-end designations.
Entry level NAS, typically found in the low user count/small office environment, is composed of low cost "appliance"-type devices that add networked storage capacity but are limited in the number of clients they can support, and offer little in the areas of high availability, expandability, and fault tolerance. A user should expect, at a minimum, file system support for CIFS and NFS. If you have or want a heterogeneous client environment, then you probably have both Windows and Unix clients using or perhaps even sharing common files between them. In these cases, both users need to be concerned about whether they can access Windows, Unix, and Apple files at the same time. Before purchasing one of these low cost appliances users should also consider carefully anticipated growth of users, amount and size of typical files expected to be stored, and most importantly, the number of concurrent users and response time needs. These entry-level units are fine for the single user or small office (less than 12 users) applications, or applications that transfer small files less than 100MB/sec in size. Serving-up large file sizes or lots of files to dozens of users can quickly send user response time to intolerable levels. So why not just add another low-end unit to the network? Consider having to now manage multiple small entry-level units instead of one, having to manage security access on each unit independently, and the tedious process of setting up twice the number of file and folder structures across multiple NAS devices.
NAS devices categorized as mid-range bring a different, richer set of storage-centric capabilities and features to the market than the stripped down "appliance" entry-class of NAS products. In fact, mid-range NAS products have much more in common (except for pricing) with the high-end category than the entry level. These products are characterized by more robust performance to handle a larger number of clients, larger file size workloads, higher availability features such as RAID disk storage, redundant hot swappable components, and a set of more sophisticated software with added functionality. This would include versatile backup support, including the more exotic features such as built-in local advanced backup capabilities like Snapshot (a point in time copy of a user volume) and Network Data Management Protocol (NDMP) support (a distributed, LAN-less backup method). Users may not think or know they need these features today but these are just what will be needed to meet growth and expansion of a business.
In many cases the "mid-range" products overlap in terms of capacity with products that carry the high-end designation. The higher cost of more robust products reflects increased performance to handle a larger user load as well as enhanced fault-tolerant design that incorporates dual server models, dual RAID controllers, and active fail-over for true mission-critical, high uptime applications.
Solutions Overview
Storage requirements are growing at 150 percent per year. The challenge facing small to mid-tier businesses is how to keep pace with the unprecedented growth and expand without impacting the availability of existing production systems and information the business has come to depend on. NAS is often the best, most cost-effective solution to this problem. In fact it is a simpler implementation than adding direct-attached storage or building a SAN. Companies that are constantly adding storage-both H/W RAID and/or JBOD-to NT and Unix file servers, those that have a need for cross-platform Unix and NT file sharing, operations with high uptime requirements, and sites that need to control storage management costs through consolidation, can all benefit by deploying NAS servers. Additionally, environments where clients put a heavy load on a single server that is servicing both files and applications can benefit by deploying NAS solutions.
Some Of The Most Common Storage-Related Problems That Are Solved By NAS:
Case #1: Network Client Server is Out of Gas. Even with newly installed client and server hardware, users can still experience volume full problems and extended wait "hourglass" problems. The source of this problem is an overburdened server, which must handle traffic for both file server and application server requests. Unless the server configuration and storage resources are tuned for the client load, the server can easily become a network bottleneck. Server performance must be able to stay ahead of the rapidly growing storage demands of the cumulative load of all network clients, otherwise performance will be unacceptable.
Adding a NAS device is an excellent solution to this problem by offloading client data to a dedicated high performance NAS device, freeing up CPU cycles on the main server to deliver faster response to applications requests. A NAS solution can provide greater simplicity and scalability compared to NT or Unix servers to keep pace with your rapidly growing demand for storing files.
Case #2: Heterogeneous Network-file sharing. Businesses of all sizes-from Fortune 1000 to very small businesses-face the challenge of computing environments composed of disparate platforms, typically multiple flavors of Unix, Windows NT/2000, Linux, and Apple Macintosh Network. Adding a new file server to such a heterogeneous environment in an attempt to share data files across multiple operating environments is a complex undertaking, creating a multitude of compatibility issues in operating systems, file transfer protocols, and user and group security permissions.
Case Problem 2: Heterogeneous Network Installation. A better solution for this problem is the installation of a NAS device. Instead of bringing down the network to add a new NT or Unix server, the NAS attaches to the network via a simple Ethernet connection without interrupting network traffic. Because it uses a more efficient OS, the NAS functions seamlessly with other operating systems by supporting the Windows NT CIFS protocol and NFS for Unix and Linux, and even AFP for Apple or NCP for NetWare.
Case #3: Exponential Data Growth-Technological Obsolescence. With storage requirements growing at unprecedented rates-particularly among Internet business-one of the biggest challenges facing network managers is keeping pace with this growth. Huge digital, audio, and video files, email archives that are never deleted, and massive Oracle databases are some of the applications that are driving this storage explosion. Unfortunately, the traditional model of simply adding more storage capacity to an existing server is outdated for the needs of this new age of storage. The cost, complexity, and limited scalability makes conventional server-attached storage obsolete for many applications.
Again, NAS technology offers a better solution for this storage problem. A unique feature of one NAS solution can expand capacity online for the addition of storage and user upgradeability that can increase the usable capacity while protecting the customer's investment in the base server platform. Hot-swappable drives make upgrades easily accomplished in a matter of minutes, with no downtime or interruption to client data availability.
Case #4: Automated Backup without burdening the LAN. The traditional overnight backup window is rapidly disappearing in the global Internet economy as enterprises are increasingly operating on a 24/7/365 basis. But trying to perform a server backup while users are running server-based applications or accessing files can be a major problem. Backup operations place a high demand of the server CPU, I/O ports and disk drives and as a result can dramatically degrade server response time for other users. NAS servers also address one of the most crucial issues facing network and IT managers: how to effectively backup data when enterprises are increasingly operating on a 24/7/365 basis.
As one example, the Connex N3000/N3100 mid-range NAS device provides two innovative solutions to this problem. Its native backup utility can directly backup and restore critical data files locally without creating backup traffic that will impact network performance. As a result, network administrators can perform a backup operation anytime of the day or night without a noticeable impact on file I/O performance for network clients. The Connex NAS unit also supports Network Data Management Protocol (NDMP) 2.0 out-of-the-box; which enables NDMP compliant backup software to remotely schedule and execute backups, again without impacting file I/O performance. This feature is not present in any low-end NAS device and supported only on some of the high-end NAS devices like Network Appliances. The three major backup applications supporting NDMP are SyncSort Backup Express, VERITAS Netbackup, and Legato Networker. The Connex N3000/N3100 offers an internal AIT-2 tape drive, providing fast backup of up to 100 gigabytes of critical data. For broader larger backup requirements, an external SCSI connection is provided on the N3000 and N3100 allowing the use of even higher-capacity third-party tape libraries to handle high capacity backup. Again both of these backup solutions have no impact on network traffic, as the backup data path is internal to the NAS server.
NDMP is a fairly new protocol that addresses network backup issues. With the industry pressure of narrowing backup windows and network bandwidth consumption during backup and restore operations, backup application vendors developed a LAN-Less backup method NDMP, which is now being accepted as an industry standard. It was a combined effort between backup application vendors and network attached storage vendors. NDMP meets the customer's strategic need to centrally manage and control distributed data, while minimizing network traffic.
Case #5: Too Much Downtime/Need for Higher Availability. In a 24/7 environment, downtime can be fatal. The complexity of most conventional NT servers almost guarantees that system "hangs" and other glitches will be common occurrences, with each instance requiring a server reboot. An actual hardware component failure is even more disruptive, requiring the customer to send the faulty component-or in some cases the entire server-to the manufacturer for warranty service, generating downtime of weeks or months.
Mid-range NAS units should be engineered for high uptime such as simple, accessible CRU (customer replaceable unit) modularity, eliminating the complexity inherent in servicing standard applications servers. Most NAS has a proprietary "thin" operating system that provides very fast execution and is not subject to potential pitfalls by supporting multiple software drives and application codes that lead to incompatibilities and conflicts that can cause the server OS to lock up. Redundant hardware architecture protects the NAS against a component failure that would cripple the server with redundant power supplies, cooling fans, and RAID-5. In the event that a hardware component does fail, the modular design allows all components to be user replaced in a matter of minutes. Even with a worst case failure of the main motherboard, a replacement module can be installed in less than five minutes.
Steve Rogers is the director of technical marketing at Connex (San Jose, CA).
www.connex.com |
