digital versatile disc random access memory (DVD-RAM)
DVD-RAMs are rewritable DVDs that can be recorded and overwritten any number of times, between 100,000 and 1 million times. Developed by Hitachi, Toshiba and Matsushita, DVD-RAMs are contained in a cartridge, also called a caddy, for protection.
DVD- RAM competes with DVD-R, DVD-RW and DVD+RW formats, with which it is incompatible. In the first version, DVD-RAMs had a storage capacity of 2.6 GB per side, in the second version they correspond to the DVD types DVD-5 with 4.7 GB and in double-sided version to DVD-10 with 9.4 GB.
The DVD-RAM uses the phase-change process as the writing method. To achieve the most uniform information density possible on the DVD-RAM, it uses a special recording method, Zoned Constant Linear Velocity(ZCLV), with zoning, which has a constant linear velocity within certain zones. DVD-RAM uses the Universal Disk Format( UDF). The DVD-RAM writes data in both groove and country. For addressing, the write layer is divided into sectors and tracks by address pits. The sectors are in turn directly separated by elevations and each has its own ID.
DVD-RAM is primarily used as removable disk storage and in backup solutions in the IT sector.