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.
This was first published in February 2003