In-Depth

A Smart Solution for Data Migration

Rainfinity's GridSwitch streamlines moving data across platforms for NFS- or CIFS-mounted storage devices.

• By Jon William Toigo
• 03/11/2004

Networked storage is nothing new, of course—though you might be amazed by the amount of confusion that persists about it in the wild. I was reminded about this recently in a phone call with Jack Norris, Vice President of Marketing for Rainfinity in San Jose, CA. His company is pushing an interesting product to "facilitate transparent data movement across IP networks" (see below) and he reports that some prospective customers are very confused.

"They tell us ‘We don’t have any networked storage’ because they don’t have any NAS storage deployed," Norris said. "But they do have 1,500 file servers that are accessed across networks using the Network File System (NFS) or Microsoft’s Common Internet File System (CIFS)." Isn’t this networked storage?

In other companies I have recently visited, I wince to hear IT managers refer to their storage area networks as networked storage. I feel like telling them that, while SAN acronym may include the term "network," they really aren’t networks – at least not in the "peer to peer with no centralized management facility sense of the term." When you come right down to it, Fibre Channel SANs are little more than a collection of dumb point-to-point channel interconnects that are made more "network-like" by terminating them on a switch.

A senior technologist for a leading storage vendor recently reminded me that iSCSI is not a true storage network protocol either, but another channel protocol that just happens to use a network—IP—as a transport. He e-mailed me the following:

"I totally agree that FC is not a network in the sense we tend to call networks today. Perhaps one point to keep in mind that the current network definition is rather new, it is perhaps 20 years old.

"Networks are peer-to-peer architectures with no centralized control. FC is a channel architecture and in its heritage one can see the IBM multiplexor channel, serials Hippi, etc. Channels are 'master/slave' architectures WITH centralized control … iSCSI by the way is [also] still a channel architecture. While it has been layered on a ‘true network,’ the relationship between the initiator and the target has not changed.

"It just happens that storage connectivity has been the area owned by computer architects, and not by networking architects [so the semantics of channel I/O have been perpetuated and perhaps inaccurately called networks]. My feeling is that we actually need to invent a new storage-application semantics (needed anyway for object storage) which can better take advantage of ‘networking’ architectures."

The whole issue would be an exercise in splitting hairs were it not for the hurdles that these inaccurate uses of terminology created for companies such as Rainfinity. The company has recently announced a new product, GridSwitch, to address an increasingly common problem in network-accessed storage: migration.

Imagine having to move a million files from NFS-mounted storage on one server (NAS or direct attached) to NFS-mounted storage on another server. You would need to know which clients mount the file system on the server in question, quiet those clients for the amount of time required to move all the files, then manually re-point all of the servers toward the new repository. According to Norris, this is a new task that has been visited upon storage managers and server administrators with the penetration of NAS and the growth of data in most organizations. He says if it isn’t a buzz hassle now, it shortly will become one.

Enter GridSwitch. According to Norris, you just plug his appliance into a set of ports on your existing switch and bring it on-line when you need to do a cross-platform migration of your data. A virtual LAN (VLAN) is established between the network-attached storage platforms and persists until you shut it off. Files are moved across this VLAN while the appliance handles any requests from clients for file access, redirecting them to the new platform if that’s where the files are.

Over time, most clients will re-mount the storage at its new location. Once this has happened, you just take the GridSwitch out of band and let networking nature take its course. The technology makes the entire process of moving data about in your network transparent to the user and simpler for the administrator.

Moreover, throttle controls are available that enable you to set up the transfer as a background task so that it uses little bandwidth in busy nets, and GridSwitch has been designed to be wholly compatible with other controls on intelligent IP network switches so you can leverage scheduling capabilities that further control bandwidth utilization.

GridSwitch seems like a smart solution to a burgeoning problem. It enables so-called "storage grids" from Network Appliance and others to deliver at least part of their advertised value proposition by facilitating data movement among NFS- or CIFS-mounted storage devices.

The only unfortunate thing about the product is its name, which Norris said was selected to piggyback on all that expensive marketing that other storage vendors are doing around "grid-this" and "grid-that." Nothing about their products or this product has anything to do with grid computing. The good news: Norris says GridSwitch is an integration module for RainStorage at no additional charge.

Hate the name, but we get the point and we like the idea. GridSwitch is worth a look. E-mail us with your opinion: jtoigo@intent.net.