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Network Direct Attached Storage

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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. 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".[1] By 2002 the first NetDisk (up to 80 GBytes) was marketed as a low cost alternative to full computer based network storage options. In 2004 Kim applied for a patent to allow multiple clients write access to the shared block storage device.[2]

By 2006, sizes up to 500 GBytes were supported.[3] 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.[4] In 2011 IOCELL Networks announced ownership of the NDAS system and NetDisk patents.[5]

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, as USB and eSATA allow access by only one host.
  • The disks do not require special formatting so they can be treated as external disks and used 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

  • The LPX Protocol is not routable, thus limiting access to the local LAN. (Uses with VPN or FTP access to a computer on their network can locate the NDAS drive via that host.)
  • 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 (e.g. Fedora, Ubuntu and Debian GNU/Linux) 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. See Using NDAS with RedHat GFS and Sharing NDAS drives using OCFS2 from Oracle

References

  1. ^ 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.
  2. ^ 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.
  3. ^ "Ximeta NetDisk Portable". Review. CNet. November 2, 2006. Retrieved June 1, 2013.
  4. ^ "The World's Fastest Network Storage" (PDF). Ximeta, Germany. May 2008. Retrieved June 1, 2013.
  5. ^ "IOCELL Networks Purchases Innovative NDAS Technology". News release. IOCELL. August 4, 2011. Retrieved June 1, 2013.
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