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Using DVD drives for a WORM RAID storage system

IP.com Disclosure Number: IPCOM000125930D
Original Publication Date: 2005-Jun-22
Included in the Prior Art Database: 2005-Jun-22
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Abstract

This device uses DVD recording drives behind a redundant, highly available RAID controller set to create RAID sets across DVD media. A library configuration uses a robot to load the media via cartridges that contain the entire RAID set.

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Using DVD drives for a WORM RAID storage system

Disclosed is a device that uses DVD (Digital Versatile Disk) drives behind a redundant, highly available RAID (Redundant Array of Inexpensive Disks) controller set to create permanent storage for vital records. Many industries are either now, or will soon be, required to store vital data for several years on WORM (Write Once, Read Many) media. To date, the only long-term storage available with fairly high capacity has been tape drives or single DVD drives. Tape media is high capacity, but is not as durable as DVD media, nor can it be effectively write protected. DVD media is durable, and has a very long shelf life, but single disks have a limited capacity, and are not fault tolerant. If the disk fails, all the data is lost.

This device uses a set of DVD drives that act as a RAID disk set, utilizing RAID 0, 1, or 5 methodologies to provide a variety of available options to the user. The RAID levels are the same as used with standard disk-based RAID systems, and include the same advantages and disadvantages in each case. Based on the particular RAID level used this results in better (read/write) performance and/or higher data protection.

Two or more redundant RAID controllers reside in front of the DVD drives, and provide the access for the hosts. A multipathing driver that resides on the hosts controls access down the multi-redundant paths, and the RAID controllers process and write the data to the DVD drives. As with the large disk-based RAID devices of today, the DVD RAID is written to as a single volume, with control of the individual disks themselves handled by the RAID controllers. This provides a highly available host-side interface.

Each RAID set is used as a single volume. If a separate volume is to be accessed, the host system communicates with the RAID controllers, which in turn locate the desired volume's cartridge in the library, and request the set from the library's robot. The robot then unloads any DVD media currently in the drives into their own cartridge, stores that cartridge, and retrieves the target media, loading each DVD into its respective rec...