New options may ease NAS management, improve scaling

Posted on July 01, 2002

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By Heidi Biggar

Venture capital firms have invested big bucks in a new category of storage products that many believe may hold the key to helping end users better manage and scale network-attached storage (NAS) environments. Are they the quick fix that users have been looking for? The verdict is still out.

Raymond Paquet, vice president and research director for Gartner Research, says that some of the technologies may actually create as many problems as they solve. Other analysts say it depends on the size of the environment and the type of product being used.

Dan Tanner, a senior analyst at the Aberdeen Group consulting firm, in Boston, says that one potentially promising approach is the file switch from Z-force, which takes existing NAS devices and "aggregates" them into an array for purportedly simpler management.

An alternative approach is to use distributed file systems to aggregate NAS units into a single logical pool. While available products may vary in terms of device support, global reach (local or WAN support), etc., the products share the common goal of trying to ease NAS management and improve scalability using software. A sampling of players in this space includes Acirro, 1Vision, Scale Eight, and Z-force.

The so-called "brains" of Acirro's Acumula software is its Global Distributed File System (GDFS). This technology embeds aggregation, smart replication, and automated capacity management capabilities into a distributed meta-file system.

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The file system runs on Acumula Software Nodes, which are attached to local NAS devices at a user's various enterprise locations. Each node communicates local storage and network characteristics through the metadata infrastructure.

Acumula aggregates all LAN- or WAN-connected NAS devices, virtualizes the volumes and files, and then presents them as a single logical view to administrators, users, and applications (see figure). Files are parceled into usable pieces, which are optimized and distributed over the LAN or WAN using a high-performance file distribution protocol (FDP). File metadata exists at all locations, which allows the software to keep track of all files in the distributed environment.

IT managers benefit from a single logical view and management of NAS devices, users, and applications. End users benefit from transparent, fast access to shared files.

The software interfaces with CIFS and NFS as well as DAFS and has a Web-based management tool that provides local and global storage statistics. Also, it allows IT managers to view storage usage patterns over time and monitor statistics for packet delivery between GDFS nodes.

Acumula is priced at $7,500 per node (one node is required at each enterprise location). Managed storage modules are also available and cost $2,500 per 250GB.

1Vision
1Vision is positioning its vNAS distributed file system in the growing Windows-based NAS market. Company officials claim that the file system, which aggregates NAS resources into logical storage devices and volumes, can lower administration costs by as much as 50%.

While 1Vision's initial product is Windows-specific, the company plans to port the software to Unix and Linux. The vNAS road map does not currently include support for EMC or Network Appliance NAS filers.

The key to vNAS is the company's persistent file system (PFS). Initially developed to help end users keep track of files on removable media, PFS is an optimized b-tree database that runs at the kernel level and supports more than four billion objects and some basic policy-making capabilities. It runs in parallel with a device's own file system (such as NTFS). The PFS must be installed on every NAS server.

vNAS is priced on a per-server basis, ranging from $700 to $5,000. File-level access, aggregation, volume spanning, and load balancing are included. Optional "plug-ins" include an enterprise console, migration daemon, back-channel access, block-level access, multi-device mirroring with software fail-over, remote access, and provisioning and billing.

Scale Eight
Scale Eight is expected to make its Distributed Storage Software (DSS) generally available to end users later this quarter. The software, which creates a large-scale single-image pool out of distributed NAS nodes, will be initially rolled out on Scale Eight hardware, but will be offered as a stand-alone product—capable of running on any qualified vendor's NAS box—in the future.

Unlike conventional NAS, Scale Eight NAS nodes connect to the LAN via a Gigabit Ethernet switch on the front (for data transfer); a second switch provides connectivity to the control/maintenance network on the back-end. To the LAN, the configuration looks like a single NAS appliance. The software supports NFS and CIFS protocols.

Analysts say this type of architecture allows users to easily scale their NAS environments both locally and in geographically dispersed locations. DSS can read/write to the same file system, cache hot files, or mirror the entire file system. The software uses block-level delta updates to minimize network traffic.

Z-force
The main idea behind Z-force's technology is to turn a cluster of NAS devices into a single, scalable, higher-performing array using a file switch. In concept, the file switch is similar to RAID controllers and Web switches used in hard-drive and server markets, respectively.

"Clustered NAS architectures have run out of steam," says Vladimir Miloushev, president and CEO of Z-force. "Companies using this technology face severe manageability and performance issues and cannot cost-effectively increase storage capacity." The company claims its switch technology addresses these issues and can be implemented at significantly lower cost than existing NAS cluster technologies.

The file switches are usually implemented in pairs for fault tolerance. Additional switches can be used at remote locations to reduce latency between primary and remote sites. Each array is managed as a single file system, which allows for non-disruptive upgrades, and supports capacities to 128TB and speeds to 2,400MBps. Any CIFS or NFS device can be connected to the device.


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