Published: 05 Feb 2003
For companies trying to enter the network-attached storage (NAS) market, issues such as cost and ease of deployment come into play. For organizations that already have NAS installations, factors such as increasing utilization, backing up data and upgrading management tools will weigh more heavily.
To help you understand where NAS is today, this article offers you a detailed look at the features of current NAS offerings and makes some suggestions on how they may fit into various storage environments.
NAS vendors all agree that almost any NAS appliance on the market today will deliver the following three features: ease of use and deployment, extraordinary value and heterogeneous connectivity using common protocols (TCP/IP, NFS v 2.0, NFS v 3.0 and CIFS). Yet while vendors agree on the broad features NAS appliances offer, they disagree on how to best deliver them.
NAS quickly won the hearts of storage administrators because of its ability to offer storage to any level of the organization, provide it with minimal--or no--additional client configuration and do it quickly. This value premise was too alluring to resist. NAS appliances were purchased and deployed with minimal thought because the upfront cost was low, support time was minimal and it kept users happy. A business no-brainer if there ever was one.
It turns out that this wasn't quite as good a deal as everyone initially thought it was. Mission-critical information quietly crept on to these appliances. One appliance turned into two. Two turned into ten. Ten turned into one hundred, and all of sudden management costs started rising and rising. With all of these appliances and data, it occurred to people that this data may actually need to be backed up and recovered. IP networks--designed to handle browser and low-level connectivity--suddenly got pressured to back up gigabytes and terabytes of data, a task that was probably not considered in the original network design.
With these new management problems, another reality set in: complexity. The growing complexity of NAS in large environments drained much of the initial excitement away from these filers. No longer did every NAS solution provide the quick storage fix some organizations had gotten used to. Even though companies such as Dell and Network Appliance provide central management consoles or allow their appliances to plug into existing consoles, the explosion of data and devices has overwhelmed some companies lacking a well-defined strategic storage plan.
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Managing the complexity
With the recognition of this management complexity--especially in enterprise environments--a number of tools and approaches to manage or reduce this complexity are emerging. The effectiveness of each of these tools and approaches varies, depending on what each organization's current NAS environment looks like.
Needless to say, the more one owns of one vendor's NAS equipment, the easier it is to get a handle on the management of that environment. NetApp's Data Fabric Manager (DFM)--which allows administrators to manage hundreds of NetApp products from a single DFM console--can recognize its NAS filers several product generations back and manage them with this tool. This ability to manage current and legacy NetApp products gives an organization that has standardized on NetApp filers a significant management advantage over organizations with a mixed-vendor NAS environment.
Another advantage NetApp offers over their competitors comes in the backup space. While the Network Data Management Protocol (NDMP) provides backup help, NetApp's SnapVault software offers the ability to migrate data snapshots between two of their filers. This option provides organizations a 24-hour window to do backups. One set of data could remain in production, while the snapped copy of the data gets backed up to tape. NetApp also integrates well with backup products such as Veritas' NetBackup and Tivoli's Storage Manager. These products use NDMP to back up snapshots from filers to tape. Since the backup is from a snapshot, there's no risk of backing up open files and it greatly reduces the amount of time that the production application needs to be offline.
Dell offers a different vision of NAS management.
NetApp powers their filers with their proprietary ONTAP OS, contrasting with Dell's strategy to power NAS appliances based on Microsoft's Windows 2000 Server Appliance Kit (SAK). Dell's NAS Product Manager, Marc Padovani, believes this approach more accurately reflects the mind set of cost-conscious organizations. Dell sees more organizations moving toward a Windows-based environment and is aligning its storage infrastructure strategy with that corporate movement. It believes that by using NAS appliances based on Microsoft's SAK, organizations may utilize their existing Microsoft trained and certified staff to manage Dell's appliances as just another node on their Windows network. This ability to manage any Windows-based NAS appliance may possibly--by Dell's own admission--be extended to include any vendors' Windows-based NAS appliance, such as Hewlett-Packard or IBM. However, Dell hasn't extensively tested this functionality in their labs.
Mark Nagaitis, HP's director of product marketing in its infrastructure and NAS Division, says today most enterprise shops have Windows 2000 and Unix variations on their raised floors. With HP's recent merger with Compaq, it now offers NAS filers sporting an underlying Windows 2000 or Unix kernel. The company sees these choices as important in performance-sensitive environments. Nagaitis says internal HP tests show that Unix-based NAS appliances perform better when used with Unix servers and Windows NT-based NAS appliances show similar performance gains when used with Windows clients.
HP, however, believes the real key to NAS management lies not in NAS appliances, but in the adoption of NAS heads that provide front ends to back-end storage area networks (SANs). NAS heads provide access to an unlimited amount of storage that's filtered through the NAS head. Using this model coupled with HP's ability to offer NAS heads optimized for either Windows or Unix environments, HP may be primed to offer the storage utility model that so many companies are looking for.
EMC also primarily uses NAS gateways as front ends to back-end SANs for many of the same reasons. They look to scale storage on the back end while using one logical front end for NAS file services. Currently, EMC distinguishes itself by offering its Celerra HighRoad software with this deployment. Upon receiving a file request, HighRoad intelligently determines the fastest route back to the user, whether it be via Fibre Channel (FC) over the SAN or directly back to the NAS device over IP.
With the growing use of NAS heads fronting back-end SANs, why not just use Windows files servers in place of NAS heads? There are two reasons. First, Windows file servers require the purchase of Client Access Licenses (CALs) for all clients accessing the storage. NAS appliances based on Microsoft's SAK don't need these CALs. Second, developers may optimize the Windows-based appliance for optimal file serving performance saving end users the time and expense of figuring it out themselves.
Steve Terlizzi, vice president of marketing for CA-based Z-force Inc., argues that each of the above solutions for reducing NAS complexity requires standardization on one vendor's product line, which also means locking yourself into one vendor's pricing model. Z-force plans to offer a file switch in the first quarter of 2003 that aggregates NAS appliances, no matter who makes them. Terlizzi claims Z-force's technology increases utilization and performance and also spreads the workload across NAS filers. Z-force recently demonstrated at a storage trade show how twelve of their file switches acting as one logical unit was able to manage 47TBs of storage. A diverse group of NAS vendors including Dell, Iomega, and Xtore comprise the back end of this storage pool. This type of solution may be just the technology that shops with multiple NAS arrays from multiple vendors may be looking for to consolidate and manage their existing NAS environment.
Despite the promises these new management offerings from traditional and emerging vendors hold, other questions linger. Will NAS and SAN technologies converge, or won't they? And what is this file-based vs. block-based argument all about? After all, why can't SAN and NAS just get along?
The NAS/SAN distinction
NetApp and others hope they can close the SAN and NAS gap, but this objective remains unlikely to emerge in the latest round of NAS offerings, especially in multivendor storage and operating system shops. Hitachi Data Systems plainly states on their Web site that file locking problems and the lack of a true universal file system are substantial obstacles to overcome for SAN and NAS to converge. IBM/Tivoli also supports this assumption. While IBM's years old StorageTank initiative purports the benefits of this convergence, their notable absence of any product offerings in this space raises questions if they're any closer now than when they made the initial statement about delivering this technology.
However, there's some progress on the NAS/SAN convergence front to report. Tony Prigmore, a senior analyst with the Enterprise Storage Group (ESG) says he now views the storage space as neither NAS nor SAN, but as storage networking. Semantics aside, while these two distinctions remain out of necessity for file-based and blocked-based traffic, both models appear to be moving toward the same end result--a unified storage utility.
|The added value of NAS|
Dell's NAS Product Manager, Marc Padovani, points out that without NAS, one may have to rely on a device such as a Windows file server, necessitating the purchase of client access licenses (CALs) for all clients accessing that file server. The same result can be achieved at considerable less expense with a NAS appliance deployed on an existing LAN without using CALs.
EMC's director of platform marketing, Paul Ross, agrees that NAS provides an extraordinary value. EMC typically deploys NAS as part of massive server consolidations to achieve the same price and performance returns with storage. NAS' simplified management features allow NT/2000 administrators to become NAS administrators after consolidating their general purpose file servers into a unified file sharing environment. Ross says 90% of the installations EMC does involves Windows.
Further value may be obtained in enterprise NAS environments using one vendor's product line. Dell has purposefully chosen to use Microsoft's Server Appliance Kit (SAK) for development. This has no requirements for CALs, so their appliances may be managed under Microsoft's Management Console (MMC) as just another node on the network. This allows Windows administrators to manage these appliances by applying permissions and properties the same way they do for other Windows nodes on the network.
Network Appliance takes a different approach to adding value. They have a proprietary microkernel powering their appliances. This kernel interacts with their Data Fabric Manager (DFM) that allows administrators to manage hundreds of Network Appliance products from a single DFM console. If you have one of their four- or five-year-old filers, the storage may be attached to a newer filer without any issues and managed from the same console.
Chris Bennett, NetApp's director of product marketing, agrees. According to Bennett, in the late 1990s, a holy war between NAS and SAN proponents raged. The end result was what none of the storage vendors really wanted and confused customers about the value propositions and distinctions of each. As a result, some customers delayed making buying decisions.
Going forward, Ziya Aral, DataCore Software's chairman of the board and CTO, sees storage networking breaking down into approximately 75% SAN and 25% NAS, and doubts they'll merge because they serve different purposes in the enterprise. Hence HP and EMC's visions of using NAS heads providing file services with back-end SANs makes a lot of sense. These visions treat NAS as what NAS really is, an application offering file services as part of an enterprise storage network.
Assuming this distinction bears out with both NAS and SAN having a complimentary role to play in the storage networks of organizations, the focus on SAN vs. NAS becomes a moot point. Under this new view, the focus shifts from a technical view to a business view. This shift in focus results in much more of a business orientation with respect to storage needs. This orientation permits organizations to identify the nature and needs of the application or end user itself. Once identified, companies may then deploy the right combination of storage technologies (NAS or SAN) and networking technologies (Fibre Channel or Ethernet) to support the application's or end user's requirements in a cost-effective manner.
What's available now?
Dell's PowerVault brand of offerings range from the entry-level home office to the mid-tier workgroup and enterprise levels. Their entry-level PowerVault 725N provides many of the same underlying software features such as a Windows-powered OS, AutoArchive (Snapshot) and integration with Windows 2000 file management that are found on their higher-end 770N and 775N NAS Servers. While sporting an attractive entry-level price point of $1,799 for 160GB of storage, this entry-level appliance only scales up to 480GB and is limited to four ATA 133 EIDE hard drives spinning at 7,200 RPM. Dell's mid-tier 770N and 775N models scale to over 40TB with Fibre Channel, offer SCSI hard drives running at 10,000 or 15,000 RPMs and contain a 400 MHz bus that allows for faster throughput.
Dell also now sells EMC Celerra NS600. They primarily offer this high-end product in environments where their customers require higher-end features than their PowerVault line presently offers. But let the buyer beware. Unlike Dell's other offerings, these EMC Celerra NS600's aren't powered with the Windows-powered OS nor any other software features standard on their PowerVault offerings.
EMC currently sees the NAS market broken out into three tiers: the high-end, midtier and entry-level markets. Currently, they provide product offerings in the high-end and mid-tier NAS market, with the entry-level market part of their long-term vision. Their Celerra Clustered Network Server (CNS) meets the requirements of the high-end NAS market. Notably, this solution provides a NAS front end with a SAN back end to scale for growth. This solution provides a scalable solution for back-end growth, though the upfront costs for this solution likely exceeds that of the mid-tier offerings since it involves a SAN deployment.
To resolve this hole in their mid-tier offerings, EMC recently announced the Celerra NS600 to meet the needs in the mid-tier market. The introduction of the NS600 product should appeal to the mid-tier market. It offers the same underlying DART operating system found on the Celerra CNS and provides it at a price point attractive to mid-tier customers.
HP already offers storage in all three tiers of the market. In the high end of the market, HP offers both the StorageWorks NAS e7000 and StorageWorks NAS 8000. These two devices tackle the high end in much the same manner as EMC, by using a NAS head as a front end to a back-end SAN--thereby creating a fusion of SAN and NAS. The StorageWorks NAS b3000 complements the NAS 8000 in the mid-tier market. The b3000 offers both clustered and nonclustered configurations scaling up to 27TB. Finally, the NAS b2000 provides a good starting point for small businesses, departments or remote locations and branch offices looking to provide file services.
NetApp also addresses all three tiers of the market, but until its recent announcement with HDS, it was the only one to do so without throwing a SAN back-end into the mix. Its recent entries in the enterprise market--the FAS960 and FAS940--provide the SAN/NAS convergence in the form of a single controller. The FAS960c provides the ability to scale to 48TB in a single system and manage 8TB in one volume. These numbers compare favorably with competitors such as EMC which puts a SAN on the back end, but its solution only scales to 52TB. While other factors such as performance and utilizing what you have may sway a decision, the ability to offer raw storage in single frame becomes hard to ignore just for the sheer simplicity of it.
As a result of NetApp's recent joint announcement with HDS, the companies now have a presence in market niches they previously lacked. HDS gains a quick entry into the NAS market via the NetApp enterprise NAS gateway solution and NetApp may now offer a NAS head solution with a back-end SAN without having to partner with one of their NAS competitors: HP, EMC, or IBM.
IBM also provides offerings in all three tiers of the markets. Their NAS Gateway 300 follows the EMC and HP models of NAS gateways into back-end SANs, while their NAS 100 and 200 models meet the needs of the departmental and low-end markets.
A plethora of vendors have NAS appliances available in the low end of the market. Companies such as Iomega offer their NAS P400m that provides 160GB of storage in their base configuration for $2,199. Snap Appliance offers a comparable product they boast can be up and running in five minutes, which comes with 160GB of storage and in RAID-0 and RAID-1 configurations.
About the author:
Jerome Wendt is an independent writer specializing in the field of open systems storage and storage area networks. He has managed storage for small and large organizations in this capacity.