Network Direct Attached Storage

Network Direct Attached Storage (NDAS) is a proprietary storage area network system, originally marketed by the company Ximeta, for connecting external digital storage devices such as hard-disks, flash memory and tape drives via the Ethernet family of computer networks. Unlike other more common forms of networked storage, NDAS does not use TCP/IP to communicate over the network. Instead a Lean Packet Exchange (LPX) protocol is used.^[1] NDAS also supports some limited RAID functions such as aggregation and mirroring.

History

In 2001, Han-gyoo Kim of Korea and Zhe Khi Pak of Russia applied for a US patent on a "network-attached disk".^[2] By 2002 the first NetDisk (up to 80 GBytes) was marketed as a low cost alternative to full computer based network storage options. The Ximeta company was founded in 2003.^[3] In 2004 Kim applied for a patent to allow multiple clients write access to the shared block storage device.^[4] By 2006, sizes up to 500 GBytes were supported.^[5] In 2008 an NDAS device called "ShareDisk Gigabit" created by Co-World Cs in Germany briefly claimed the title of world's fastest network storage device.^[6] In 2011 IOCELL Networks announced ownership of the NDAS system and NetDisk patents.^[7]

Benefits

• Hardware is typically easy to set up and use, particularly when a unit is purchased with a disk installed.
• The disk drive can be used via multiple interfaces (typically eSATA, USB or Ethernet) though not concurrently: USB and eSATA allow access by only one host.
• The disks do not require special formatting so they can be treated as external disks on a wide variety of computers.
• Performance (speed vs. cost) is claimed to be better than similarly priced storage devices.
• Devices are isolated from external network discovery since the protocol is not visible through a router.

Drawbacks

Linux Driver Project Code - chunk of GPL code from the NDAS driver

• The LPX Protocol is not routable, thus limiting access to one local area network.
• Some firewall programs block the LPX protocol by default. It uses EtherType value 0x88AD.
• Drivers required to operate NDAS devices over a network are not shipped with operating systems. The devices are usually accompanied with client driver software for Microsoft Windows operating systems.
• Drivers for Linux-based operating systems (Linux distributions such as Fedora, Ubuntu or Debian) are available only from the manufacturer. The Linux connection package does have a shared read and write access mode. However it must be used with a multi-client file system.^[8]

An open source management interface was made available for Linux in 2009.^[9]

A similar protocol is ATA over Ethernet.

References

1. Bruce Normann (November 28, 2011). "IOCELL NetDISK 351UNE Network Storage Device". Benchmark Reviews. Product review. Retrieved June 1, 2013.
2. Disk system adapted to be directly attached to network. U.S. Patent 7,792,923 by Han-gyoo Kim and Zhe Khi Pak, Filed October 9, 2001, granted September 7, 2010.
3. "Ximeta: Creator of NDAS". Retrieved June 1, 2013.
4. System using a single host to receive and redirect all file access commands for shared data storage device from other hosts on a network . U.S. Patent 7,457,880 by Han-gyoo Kim, Filed September 27, 2004, granted November 25, 2008.
5. "Ximeta NetDisk Portable". Review. CNet. November 2, 2006. Retrieved June 1, 2013.
6. "The World’s Fastest Network Storage" (PDF). Ximeta, Germany. May 2008. Retrieved June 1, 2013.
7. "IOCELL Networks Purchases Innovative NDAS Technology". News release (IOCELL). August 4, 2011. Retrieved June 1, 2013.
8. "Network Direct Attached Storage For Linux". Vendor web site. Retrieved June 1, 2013.
9. "kandas: Management infrastructure for NDAS devices". Google code web site. Retrieved June 1, 2013.