DVD recordable higher-capacity formats like Blu-ray and HD DVD. A double-layer DVD+RW specification was approved in March 2006 with a capacity of 8.5 GB. However, manufacturing support for these rewritable dual-layer discs did not materialize due to costs and expected competition from newer and higher-capacity formats like Blu-ray and HD DVD. DVD recordable DVD recordable and DVD rewritable are optical disc recording technologies. DVD optical disc formats that can be recorded by a DVD recorder, (written, “burned”), either write once or rewritable (write multiple times) format written by laser, as compared to DVD-ROM, which is technically mass-produced by pressing, primarily for the
DVD-RAM The on-disc structure of DVD-RAM is closely related to hard disk and floppy disk technology, as it stores data in concentric tracks. DVD-RAMs can be accessed just like a hard or floppy disk and usually without any special software. DVD-RWs and DVD+RWs, on the other hand, store data in one long spiral track and require special packet reading/writing software to read and write data discs. Like magneto-optical (MO) technologies, DVD-RAM has numerous rectangles on the disc surface that define the boundaries of data sectors. However, DVD-RAM is not MO but a phase transition medium, similar to CD-RW, DVD-RW, or DVD+RW.