Three Appliances Raise the NAS Bar

By Henry Baltazar  |  Posted 2003-04-14

Three Appliances Raise the NAS Bar

During the last two years, network-attached storage systems have made their way into virtually every type of organization—from small companies to the largest of enterprises—and several newly released products demonstrate that NAS is becoming more flexible, scalable and reliable than ever before.

eWEEK Labs recently evaluated three products that both augment NAS and push it to new levels. During our tests, we found that each of these products includes powerful capabilities that have the potential to change the way organizations view NAS today and prove that NAS technology is good for more than just quickly replacing file servers and adding network storage. Indeed, these products are truly breaking new ground.

In many IT departments, a hotly debated topic is whether file-level (NAS) or block-level (SAN) access is the best way to store data.

A major player in the NAS- versus-SAN (storage area network) debate is Network Appliance Inc., which, in the past, fought tooth and nail against SAN vendors for the storage hearts and minds (not to mention wallets) of organizations. Instead of continuing the battle, Network Appliance officials have said, a decision was made to build a solution that blends the capabilities of both technologies.

The Network Appliance FAS900 Series appliances give IT managers the flexibility to do file- and block-level storage on the same hardware platform while simplifying management of storage resources. The FAS900 Series appliances won the storage category in the third annual Excellence Awards program, and a full review of the FAS960 starts at right.

As NAS devices have proliferated, a common problem that IT managers have encountered is difficulty in spreading the workload across multiple units. Rainfinitys RainStorage appliance allows IT managers to easily migrate data away from overworked NAS devices and onto new and underused ones.

And although NAS has worked solidly in LAN environments, it was not viable across WANs. Tacit Networks Inc.s new SC/IP (Storage Caching/IP) technology allows users in remote offices to access and modify data using a blend of streaming data replication and read/write caching technologies.

The true beauty of the Tacit Storage Cache/Tacit Cache Server solution is that it works seamlessly with well-known protocols such as CIFS (Common Internet File System) and NFS (Network File System) and so should easily plug into most networks.

FAS900 Series Appliances

FAS900 Series Appliances

NAS or SAN? Network Appliances FAS960 (FAS stands for Fabric Attached Storage) answers that question by providing both in a single, powerful solution.

After years of fighting with SAN vendors, Network Appliance has turned the tables on its competition by providing customers with a solution that has the benefits of both file- and block-level storage, with a single point of storage management.

During tests of the FAS960, part of the FAS900 Series, eWEEK Labs was impressed by the appliances manageability and flexibility.

In fact, flexibility is a major benefit. In tests, we could easily hook into our test unit using a Fibre Channel SAN connection or via IP-based CIFS file sharing. IT managers can easily shift resources to either the NAS or SAN side as storage needs change and as new applications are deployed.

Network Appliance FAS960

The FAS960 (see photo on left) can scale to as much as 48 terabytes of storage (up to 8 terabytes in a single file system). In our test configuration, we had 4 terabytes of raw storage running on a single FAS960 head unit.

In the FAS960, LUNs (logical unit numbers) are carved out of volumes. Network Appliance officials recommend that storage managers configure the volume size to be three times the size of each LUN (a 1-terabyte LUN on a 3-terabyte volume). According to company officials, this configuration will allow IT managers to use Network Appliances SnapShot feature for data protection. In tests, SnapShot allowed us to quickly make a copy of our data that we could restore in the event of a data volume corruption.

After we had created our test LUNs, we used the FAS960s management tools to assign the LUNs to our server. The FAS960 uses standard Fibre Channel WWNN (World Wide Node Name) and WWPN (World Wide Port Name) addresses to link targets to initiators, so anyone with Fibre Channel SAN experience should be able to plug an FAS960 appliance into a SAN.

By default, the FAS960 masks all LUNs until they are assigned to a host. During setup, the FAS960 formatted the LUNs of our Windows 2000 server to Windows NTFS (NT File System) so we could use them immediately.

The FAS960 has the ability to dynamically resize LUNs, but its important to note that the capabilities of the host operating system will determine the effectiveness of this capability. For example, Windows doesnt allow dynamic disks to be resized, while Solaris supports an increase in LUN sizes but not a decrease.

For our test application, we used Microsoft Corp.s Exchange 2000 running on a Hewlett-Packard Co. four-way ProLiant server; we moved the Exchange data store from local disks to LUNs on our FAS960.

To hook the HP server into our SAN, we installed an Emulex Corp. host bus adapter into the server, loaded up the device driver and ran a quick script from Network Appliance to make registry changes.

The FAS960, which became available in October, ranges in price from $150,000 to more than $1 million, depending on configuration. With Fibre Channel interoperability still imperfect, and considering that the FAS960 is fairly new, IT managers should carefully test for hardware compatibility before investing in a unit.

FAS960 Executive Summary



Rainfinitys RainStorage appliance greatly increases the manageability and availability of NAS systems. In eWEEK Labs tests, RainStorage migrated data from one NAS unit to another without disrupting user file access (see screen). The appliance also makes NAS resource management easy for managers, and, more important, it makes upgrades and migrations seamless for users.

RainStorage sits in front of NAS clusters in the network. When engaged, the appliance sits between the NAS systems and the users.

To take RainStorage in and out of band, we had to move VLANs (virtual LANs) around on our switch. While the process of setting up VLANs may require assistance from a network administrator, it is definitely worth the effort because leaving this appliance constantly in-band would make it a potential single point of failure.

RainStorages Web-based management tools have the ability to define custom scripts to automatically switch VLANs from in-band to out-of-band status.

When engaged, an IT manager can move data to evenly distribute workload or to move seldom-used data to a nearline storage device. In tests, it was fairly easy to start data migration, and after the process was completed, RainStorage automatically synchronized the two systems to complete transactions that took place during the migration.

RainStorage, which began shipping in January, redirects client access from the source to the new target. When user activity is down, an IT manager can switch the client mount points to hit the new NAS system and remove RainStorage from in-band mode.

The appliance has twin Intel Corp. Xeon processors, 4GB of memory, 4GB Ethernet cards and mirrored hard drives, all running on a hardened version of Linux 2.4.

RainStorages biggest negative is that it supports only NFS at this point. CIFS support is expected later this year, but until it arrives, this appliance is really worthwhile only if most of your servers and clients are Unix-based.

At $80,000 per appliance, RainStorage may seem a bit expensive. It is, but its notable that there is no licensing limit to the number of NAS systems that can be managed with an appliance. This makes the system a good buy for organizations with large NAS farms. A clustered pair of RainStorage appliances is available for $140,000.

RainStorage Executive Summary

Tacit Storage Cache

/ Tacit Cache Server">

Tacit Storage Cache/ Tacit Cache Server

Tacit Networks products allow NAS to break out of the LAN and onto the WAN.

Using a combination of low-latency replication and caching technologies, the Tacit Storage Cache and the Tacit Cache Server work together to allow NAS to be accessible over WANs. (The products must be used together.)

NAS products run file-sharing protocols such as CIFS and NFS to control data access and link remote clients to files. Although these protocols work well in LAN-type environments, performance slows to a crawl when clients are linked to NAS units over a WAN.

The obvious reason for this performance degradation is that WAN links are typically far slower than whatever is running on the LAN. The difference in data throughput between LANs and WANs, however, isnt the only reason for the degraded performance. A subtle, but far more important, reason for the degradation lies in the manner in which protocols such as CIFS and NFS work.

Both of these protocols are chatty, an attribute that can be tolerated in high-speed LAN environments but is extraordinarily painful when coupled with WAN latencies.

In Tacit Networks solution, a streaming data replication protocol (SC/IP) replaces CIFS and NFS over WAN links. SC/IP ensures that Tacit Storage Cache appliances (which are installed at remote sites) have an accurate and complete copy of the data sets stored at the home office.

Unlike other caching solutions we have seen, most of which push out read replicas to remote sites, Tacit Networks solution can support read/write storage caches. This provides users in remote sites with the ability to update and maintain shared data on an equal playing field with workers in the home office.

The Tacit Cache Server sits in front of a primary NAS system at a data center, and it coordinates communications between the NAS and the remote offices. The Tacit Storage Cache sits at remote office sites, where it holds an identical read/write copy of the primary data set that remote users can access without depleting WAN resources.

Currently, communication between the Tacit Storage Cache and the NAS device must be via NFS. (CIFS is not supported yet.) The back-end NFS limitation is expected to be overcome within a month or so.

Since data is cached at each local site, network administrators can conserve bandwidth among sites by using Tacit Cache Servers. Once data is replicated to a Tacit Cache Server, users can get to it via CIFS and NFS.

When data is updated at a remote site, the Tacit Storage Cache calculates the data changes, compresses them and sends them back to the primary NAS system.

In tests at eWEEK Labs San Francisco offices, instead of waiting seconds or even minutes to access various files from a remote data center in New Jersey, the Tacit Cache Server gave us virtually instantaneous access to our data.

The Tacit Storage Cache costs $22,500, while Tacit Cache Servers cost $21,500. The products began shipping in February.

While Tacit Networks solution is the first we have seen that tackles the NAS-over-WAN challenge, there are a couple of other vendors to keep an eye on in this space.

The WebOffice Inc. VPSN (Virtual Private Storage Network) system blends intelligent file transfer technology with VPN technology to create a secure private network.

WebOffices S-Transfer technology keeps track of file transfers so that the process does not have to begin from the beginning in the event of a machine or network failure.

WebOffices system integrates a switch, firewall, NAS and VPN in a single box, which makes it ideal for small-office environments.

eWEEK Labs has not had a chance to compare this unit with the Tacit Networks solution, but based on what we have seen so far, these products have some similarities. More information can be found at

Another vendor to watch is DiskSites Inc., whose W-NAS solution is closer to Tacit Networks because it combines caching capabilities with compression. For more information, go to

Tacit Executive Summary

Senior Analyst Henry Baltazar can be contacted at

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