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posted on 20 August 2008 10:23

By launching itsdsNet product, start-up Cleversafe aims to grab slices of the storage cake by dispersing parts of files in coded form across multiple nodes with space-efficient recovery that discards RAID. Many of its customers will be cloud storage serrvice suppliers.

Files are cut up into sections, called slices, and stored in a coded form on different nodes. Each slice contains coded slice data and a proportion of coded file data so that multiple nodes can fail and the file can still be recovered. As the slices contain mathamatical transformations of the original data the file is, in effect, encrypted, and the node's content unreadable, making it secure.

Three pieces of hardware are needed for this:

1.) A dispersed storage router or Accesser which slices-and-dices data, by applying an encoding information dispersal algorithm, and sends the coded slices to storage nodes called:
2.) Dispersed storage servers or Slicestors, a 1U slice server,  which store slices in their 3TB of raw disk capacity . These are mini storage vaults and can be combined in unlimited numbers. They can be mounted in a single rack or racks or dispersed locally or remotely.
3.) A Manager is the dispersed storage network manager and provides management access and reporting via an SNMP MIBs interface. It polls the Slicestors for data to create dsNet management statistics.

CleverSafe has supplied five storage service suppliers in and around its Chicago base who supply their services to end-user customers as mini-stirage service clouds. The end-users see an extra dsNet drive on their screens which is accessed by iSCSI and to and from which data can be written and read. Their systems use a lightweight dsNet software client to do this and Cleversafe says it works with any O/S or file system. This clent talks iSCSI to the Accessers which implement the dsAPI, a protocol to interact with the Slicestors.

This dsNet client takes up 3MB of space and Cleversafe sees it hopefully being used on intelligent mobile and fixed devices such as smartphones, media players, secirity cameras and set-top boxes.

In the relatively near-future a WebDAV interface will be added which will give each dsNet stored file a URL and provide access to it from any browser. We might envisage a NAS interface offering NFS and CIFS as another possible addition.

Cleversafe says dsNets offer limitless scale and that customers can choose the level of reliability they want. They could have a set up with 8 slicestors, three of which can be lost without affecting data recoverability. In a 16 Slicestor set-up 6 of them could be lost. A 26-byte file would be stored in 16 slices with a total of 58 bytes required to provide the protection against node loss. That is a 60 percent storage overhead with the total bytes stored equalling 1.6 times the usable capacity.

Russ Kennedy (left), Cleversafe's VP for Product Management and Strategic Alliances, said about this: "It's much more reliable than RAID6, where you can lose two drives. You can set the dsNet reliability levels, for example, 16 slices with a threshold of 10, meaning you lose up to six slices."

Cleversafe founder, CEO and president Chris Gladwyn, added: "RAID is not designed to deal with dispersed storage. All drives are meant to be in one place. dsNet has geographical redundancy built in. (Also) with RAID you're still actually storing (raw) data and so it's less secure."

Deduplication is not offered but is an item on Cleversafe's roadmap. A suggestion is that a deduping server could sit in front of a dsNet.

Gladwyn (left) says a slice is equivalent to a TCP/IP packet and Cleversafe's technology applies Internet principles to storage. He asserts that traditional storage architectures eventually run into a wall as they scale because RAID, when applied to thousands of drives, means a vast amount of extra storage is required to provide protection against drive failures and the amount of synchronisation required inside the system becomes far too burdensome.

The data in a dsNet is virtualized at the byte level and is inherently secure and private. It can scale up to hundreds of petabytes which traditional storage architectures can not.

So far it is scaling to 48TB with a 5-location dsNet in the American mid-west. Half of it is for Cleversafe's own use and the rest is for the five partners in Cleversafe's First Mover marketing programme - merrimac solutions, onShore, fastroot, Pinpoint, and the Cyber Development Group, who will use it as the storage in their offerings to their customers.

Asked to compare dsNet with Nirvanix, Kennedy said Nirvanix' Storage Delivery Network (SDN) was analogous to a content delivery network. "We see dispersed storage as more reliable as well as a much more cost-effective solution. We see Nirvanix as complementary. We don't deliver a service as Nirvanix does. We provide a technology."

Cleversafe is following a ground-up marketing strategy and it will be interesting to see how the use of dsNet technology spreads. Because of its positioning dsNet will compete with other cloud storage service technologies offering very high scalability and that could mean established vendors like EMC, HP and IBM, and startups like Parascale. Clearly it will also compete with the technology used by Nirvanix, as well as seeing its customers offering cloud services in competition with Google, Amazon's S3 and Microsoft.

It's sure going to be an intense technology and marketing storm inside the storage cloud. Grab your umbrella and watch out for the thunder and lightening.

^{[Chris Mellor.]}