On Fri, 2 May 2003 00:06:42 +0200 (CEST)
"Carlos E. R."
What is a dvd-ram? :-? A dvd writer, perhaps?
dvd-rom -> read-only dvd-ram -> true random access, read and write dvd-rw -> 1 pass sequential read and write It's basically a cdrom-dvd-reader, and a dvd-ram writer. It acts just like a hard drive, just plug it in to the ide bus. No mkisofs or udf needed. Just format it like a harddrive and start copying to it. It uses special dvd-ram cartridges which are good for 100,000 writes. They have a special design which make them very reliable storage, better than tape, and the are cheap, around $8 for 2-sided 9.4 gigabyte blanks. It's high reliability makes it suited more for backups and data storage than for playing back movies, but you can record your movies on them. Check them out on Ebay. There is a new generation coming out, so the older units are now cheap as heck. More Info below. Most of this post is from the iZ site (www.recordingtheworld.com) but I thought folks here would be interested. Some interesting info that may help clear up some of the confusion on the DVD-RAM technology and its future. DVD-RAM is a completely different technology designed for different applications than any of the other formats such as DVD-R, DVD-R/W or DVD-R+. DVD-RAM is specifically designed for a minimum of 100,000 read/write cycles (much more than even a floppy disk) so it can be used effectively as a RELIABLE backup/restore media and for transferring files between systems over and over again. Unlike DVD-R where the data layer is on the top surface and vulnerable to scratches, the data layer in DVD-RAM is embedded between two layers of plastic and the disk itself is in a protective cartridge. Because of the embedded nature of the data layer the disk is much more robust than the write once formats even if you take it out of the cartridge. Since DVD-R and DVD-R+ are write once they are fine for archiving but like a CD ROM they are NOT reusable. Even DVD-R/W which is re-writable is limited to a small number of re-write cycles. The reason that some manufacturers have reconfigured their systems for DVD-R over DVD-RAM is because DVD-RAM was on the market first and they had no other choice at the time. Now that DVD-R is finally here it is much cheaper to design it in to consumer products. However DVD-RAM will not be replaced by write once formats especially where high reliability is important such as RADAR 24 applications where data integrity and media life is important. DVD-RAM TECHNOLOGY EXPLAINED: DVD-RAM disks are really just a cost reduced version of the old M-O drives (Magneto-Optical)drives. DVD-RAM drives use phase-change technology in which a laser heats the inner surface of the disk so that it can be magnetically charge it(just like M-O drives). This allows the data to be rewritten hundreds of thousands of times. A "wobble-land-groove" format provides clocking data, with marks written on both the grooves and the lands between grooves. The grooves and pre-embossed sector headers are molded into the disc during manufacturing. The DVD-RAM wobble-land-groove format or track structure makes DVD-RAM technology reliable, and the constant linear velocity format provides high access speed and capacity. DVD-RAM discs consist of double layers of metallic film embedded in hard plastic. The drive motor constantly changes the disc's rotational speed to compensate for the location of data on the disc. A laser uses light of varying intensities to write and erase data. The metallic layers in the disc are made of a crystalline material that reflects light the way a mirror does. To write data, the laser heats a metallic layer to 900 to 1,300 degrees Fahrenheit and creates pits in the surface. To erase or change data, a weaker laser beam heats the pits to approximately 400 degrees Fahrenheit. Single-sided DVD-RAM discs come with or without cartridges and can be read by the "newer generation" DVD-ROM drives (check your drive's specification for additional info). There are two types of cartridges: type 1 is sealed and type 2 allows the disc to be removed. Available now, single-sided DVD-RAM discs hold 2.6GB or 4.7GB of data. 4.7GB DVD-RAM disks achieve their high storage capacity from a decrease in track pitch and pit lengths, allowing for a higher density media. Today, the minimum pit length of a single layer DVD is 0.4 micrometers, as compared to 0.83 micrometers for a CD. In addition, the DVD track pitch is reduced to 0.74 micrometers, less than half of CDs 1.6 micrometers. With the number of pits equating to capacity levels, DVD's reduced track pitch and pit size creates four times as many pits as CDs. By the way, DVD-RAM has a much longer shelf life than tape. Digital Tape only has a shelf life of 5 to 10 years (yes that's right, better transfer that 3348 or DAT tape before the data is GONE!). DVD-RAM on the other hand has a minimum shelf life of 30 years. -- use Perl; #powerful programmable prestidigitation