Guide to Network Attached Storage

NAS best practices: Understand your needs for today and tomorrow

Consider data protection and management, upgrade path

By Deni Connor

There are a number of best practices to keep in mind when implementing NAS devices in your enterprise network. Here are a few issues to consider:

Many NAS appliances come with backup, replication, cloning and high-availability software. You'll need to decide which capability is right for you. Do you need to replicate data to a remote location for disaster-recovery purposes? Do you need to be able to clone data so it is available to other users or applications? Will you back up the data continuously or incrementally? Does the NAS appliance you are buying support Network Data Management Protocol, which separates the data path and the control path, so network data can be backed up locally yet managed from a central location?

Take a look at the redundant connections that are included with the NAS device. Do you need redundant Gigabit Ethernet connections to increase the performance of the box or its availability? In the same vein, do you need redundant iSCSI connections? Do you need access to the Fibre Channel storage-area network? Will using 10Gbit Ethernet connections increase the performance of your network?

Most NAS appliances allow you to upgrade the capacity of the box as your network grows. Take a look at future storage needs and decide the initial capacity for your NAS box; then decide how much capacity you will need a year from now.

NAS appliances come with management software. The breadth of the management capability varies, however. Decide whether you are going to manage a single NAS box or multiple arrays. Will the software support the management of multiple arrays? Can you set policies regarding capacity use, or does the software simply let you handle initial installation and configuration? Software is available that allows you to manage multiple NAS boxes collectively and optimize capacity and plan for future storage purchases.

Five questions to ask before you buy NAS

Have in mind size, usage requirements

By Deni Connor

Buying network-attached storage (NAS) should be a simple affair. Here are a few questions to ask yourself before you buy to make sure you're getting what you need:

You may want to consolidate several file servers so you can manage the combined storage better. If you are looking to host DNS and Web services, consider a NAS device with both Common Internet File System and Network File System support and limited storage capacity. If you are hosting engineering or computer-aided design applications, then consider a more powerful NAS system with higher capacities or a clustered NAS system for the large files that the application generates.

If you are looking to use the NAS appliance for consumer storage – to store video, MP3 and other digital files -- then a smaller, easy-to-install and configure appliance is probably best. Look at such NAS appliances as the Buffalo Technology TeraStation, Adaptec Snap Server, Infrant Technologies' ReadyNAS NV, Anthology Solutions' Yellow Machine P400T, Sabio Digital's CM-4 or Iomega's 400R.

The capacity of NAS devices is important. There's no sense in buying less storage than you will need or more storage than you can ever consume. Take a look at your storage requirements for the next few years and decide what size NAS device you need. NAS appliances come in capacities ranging from 500GB to more than two petabytes.

Look at the changes you need to make to your network infrastructure to accommodate the NAS appliance. Do you need Gigabit Ethernet to support high-speed connections to storage? Do you need to support both file-level and block-level storage-area networking access? Do you need multiple connections to the Gigabit Ethernet network to support high availability and performance?

Backing up and protecting your NAS appliance are as important as storing data on it. Are your NAS appliances in branch or remote offices? If so, you might want to use a product such as HP's OpenView Storage Mirror to copy only blocks of data that have changed at remote sites.

Many NAS appliances come with advanced features built in. But which ones do you need? For instance, do you want to be able to replicate data to another appliance for disaster recovery? Do you want to be able to move data from a NAS appliance so you can upgrade or patch the appliance or applications running on it? Do you need clustering for high availability and fault tolerance? All are points to consider before you buy.

The future of NAS devices: diversified, advanced 

Performance issues to abate

By Deni Connor

Potential buyers of network-attached storage (NAS) might ask: "What are some of the developing trends in NAS devices?" Here are a few key ones to keep tabs on:

NAS boxes will increasingly support block-level storage-area networks (SANs), as well as file-level capability. Network Appliance, which pioneered this kind of storage and called it "unified storage," introduced SAN and NAS access in a single appliance in 2002. Preceding these announcements were NAS gateway products that linked NAS appliances as front-ends to SAN arrays from Sun StorageTek, EMC, Compellent and ONStor. After Network Appliance's introduced converged NAS/SAN storage, Microsoft quickly followed by offering SAN access in its Microsoft Unified Data Storage Server 2003. Now unified NAS/SAN appliances are available from Network Appliance, StoreVault, Dell and HP among others.

In addition, manufacturers of NAS appliances will continue to incorporate such advanced features as migration, snapshotting, replication and cloning. These offerings let IT administrators automatically move data from one appliance to another to allow for maintenance, patching, application testing or development. Integrated replication, seen in Pillar Data Systems' AxiomONE Volume Replicator or BlueArc's Incremental Data Replication, will become increasingly leveraged as users seek to move data from one location or array to another.

The performance debate surrounding NAS appliances is expected to disappear. Vendors of competing SAN arrays long have claimed that NAS storage does not have the performance capabilities of Fibre Channel SAN storage. This claim is no longer true, considering the performance of Network Appliance's and BlueArc's NAS devices.

Increasingly, enterprise applications will be deployed on NAS arrays. Despite the claim from vendors of Fibre Channel SAN arrays that NAS devices shouldn't be used to host enterprise or business-critical applications, such companies as Network Appliance and BlueArc offer clear alternatives. Dozens of their users commonly deploy Oracle, Microsoft SQL Server and Exchange databases on their high end as well as midrange NAS devices.

File-management software will continue to proliferate as IT administrators struggle to control and manage bunches of NAS devices and file servers on their networks. File area networking software and appliances, such as those from F5 Networks, will be deployed in distributed enterprises. This software, which brings together individual file systems from separate NAS devices to a single file system, is intent on making management of distributed NAS devices easier.

A focus on NAS for small and midsize businesses will continue in 2008. These businesses, often saddled with a lack of dedicated IT staff, will call for simplified installation, configuration and management as an affordable price point. Look for such NAS appliances as Network Appliance's StoreVault, HP's All-in-One storage and Dell's PowerVault to make big strides into the SMB market. Also watch for NAS devices with iSCSI capability; for SMBs inexperienced with Fibre Channel, iSCSI makes sense, because it is easy to configure, less complicated to use and available at a price that won't break the bank.

How does network-attached storage work?

By Deni Connor

Network-attached storage (NAS) devices connect to a Gigabit Ethernet network and give users access to files stored on an appliance.

NAS appliances evolved out of traditional file-server environments and have both storage capacity and a file system. Like file servers, NAS devices are equipped with less expensive, slower Serial Advanced Technology Attachment or faster, more expensive Fibre Channel drives.

NAS devices come with three varieties of file systems -- those that support Microsoft's Common Internet File System, those that support the Unix/Linux Network File System and those that work with both protocols.

NAS systems range in size from 500GB at the low end to large systems offering as much as two petabytes of storage capacity. Each NAS system has its own operating system, either Microsoft Windows or a proprietary OS. Unlike storage-area network (SAN) arrays, the NAS appliance does not rely on a server to provide its access to users. A NAS system is much like a server, containing its own CPU, motherboard and RAM.

Like SAN arrays, NAS appliances have a number of high-availability, replication and clustering capabilities, depending on their size and price.

NAS got its start in early file-sharing environments, such as Novell's NetWare, which used the NetWare Core Protocol. In 1984, Sun developed the Network File System. In 1992, a group of engineers from early NAS vendor Auspex founded Network Appliance, making it the first company to implement NAS as an appliance. Today, some companies, including Isilon and PolyServe (acquired by HP), are clustering NAS devices under a single global file system.

Earlier this decade, Microsoft began offering storage products, and the first were NAS appliances using Windows Server 2003. These devices are marketed and developed by companies that include Dell, HP, Iomega and EMC. Windows Storage Server 2003 R2 devices include advanced availability features, such as point-in-time data copies, replication and server clustering.

NAS gateways have also been developed. In a NAS gateway, a NAS front-end attaches to the SAN and provides file-level access to the SAN's block-level storage. ONStor's Bobcat gateway is an example. NAS vendors have also started to incorporate block-level access into their appliances and call them unified storage. Among the vendors that provide such storage are Network Appliance, Pillar Data and BlueArc.

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