Optical storage

 

This topic provides an overview and reference guide for IBM® optical support to a system with the i5/OS® operating system.

These functions are unique to optical support:

The information contained in this topic is intended for the following users:

Optical storage on the system provides an economical and efficient way to store and retrieve large amounts of information at a high performance level. Optical storage devices offer significant advantages over other high-capacity storages devices, such as tape and microfilm, with faster access times and a hierarchical-type file organization. i5/OS optical storage uses files that are stored in directories and files that are stored in subdirectories similar to UNIX® or PC-based file systems.

The capacity, price, and performance of optical storage continually improve, and IBM remains committed to providing its customers with these improvements over time. Even as new devices are introduced, the basic methods of accessing optical information remain consistent, as these new storage devices are being added under the current file system interfaces that optical storage programs have used for years.

Optical storage is any storage method that uses a laser to store and retrieve data from media. Examples of this media are compact disk read-only memory (CD-ROM), digital versatile disk read-only memory (DVD-ROM), digital versatile disk random access memory (DVD-RAM), write-once read-many (WORM) cartridges, and erasable optical cartridges. These are some considerations in the use of optical storage media:

Consideration Reason for use
Durability Optical media can have a shelf life in excess of 50 years.
Archive storage Write-once read-many (WORM) optical media can be used to archive large amounts of data. Each sector on the media is only written once when creating and updating files and directories. When a file is changed or deleted, a new version of the file gets written, but the old version still exists on the media. All previous versions of the file remain recorded on the media. This capability also exists on erasable media, but the entire disk may be erased and reused.
Transportability Universal Disk Format (UDF) optical media can be read with any other industry operating system platform that supports UDF, which is an industry standard file system. Optical Media written with High Performance Optical File System (HPOFS) format can be interchanged with other optical media libraries attached to a system.
Random access Optical devices are random access devices. This facilitates the retrieval of relevant data on demand. File access is independent of the order in which the data was stored. Also, multiple users can access the same volume at the same time.

When you use virtual optical storage, you create and use optical images that are stored on your disk units. These optical images are treated as if they were real optical disk media by the internal file system functions. The term virtual applies to the emulation of the optical media sectors when used by read and write functions. Virtual optical media appear as *DVDRAM media in the volume information attributes.

  • Supported hardware for optical storage
    Various stand-alone optical devices are available as optical storage.
  • Optical devices
    Your system comes with a rack-mounted CD-ROM or DVD-ROM drive.
  • Concepts for optical storage
    This section discusses optical volumes, optical directories and files, and volume identifiers.
  • Optical media formats
    There are several optical media types and media formats used for the i5/OS operating system.
  • Configuring optical devices
    This topic provides information on configuring your CD-ROM, DVD-ROM, DVD-RAM devices, and optical medial libraries. The systems come with a rack-mounted CD-ROM or DVD-ROM drive.
  • Using optical devices
    You can display the primary menu for optical support by entering GO OPTICAL on the i5/OS command line. System administrators and programmers can access most optical commands through this menu. It is also convenient to enter many of the optical commands directly on the command line.
  • Using optical volumes
    These topics describe the Work with Optical Volumes options on the Optical Support Utilities main menu.
  • Optical volume backup
    This concept describes the methods that you can use to back up optical data from one optical volume to another optical volume or tape.
  • Managing performance in optical media libraries
    Several factors can affect the optical performance of both LAN-attached and directly attached optical media libraries.
  • Managing optical security and auditing
    You can secure information on optical media by using i5/OS security functions.
  • Reclaiming the optical index database
    A system-level index, called the optical index database, keeps track of all optical volumes and directories known to the system.
  • Recovering held optical files
    A held optical file is an optical file that could not be closed normally. This topic provides information on recovering held optical files.
  • Saving and restoring optical media
    The i5/OS Save and Restore commands support directly attached optical media library devices, CD-ROM, DVD-ROM, and DVD-RAM stand-alone devices.
  • Troubleshooting optical storage
    This topic provides answers to several of the more common questions, steps to follow when a problem occurs, and information needed for problem analysis.
  • Output file support structures
    This topic describes the three possible record formats that are created by the Display Optical (DSPOPT) command when output is directed to either an output file or user space.

 

Parent topic:

Storage solutions

Related concepts
Comparing offline storage

Related information
Tape and Optical Storage