Ram's Defect Management compared to +-R, Whitepaper by MediaSciences Inc

Just read this, as it was also newsposted in the mainpage:

Study Reveals DVD-RAM Drives Provide Most Secure Defect Management Solution Available Today

Direct link to the corresponding whitepaper here

Since we do have our own experts around here, i’d like to read some comments on this. Spaths previous article on -+R formats compared defect management of both but barely touched Ram. Spath? :slight_smile:

No surprize really, if you read the specs. DVD-RAM was designed for data storage, and has a lot of nice things if that is your goal. 100,000 write cycles for instance, compared to 1000 for either RW format. Of course I suspect all number are higher than the real world can give, even still that makes a good argument for DVD-RAM if you just want to store data. Unfortunatly it is rare, and thus expensive. I doubt the price will come down to where consumers will get a DVD-RAM drive on their computer, so in the real world few will have it.

I like my Iomega Super-DVD which does this format. The only other unit I’ve worked with is a powerfile changer. Everything else does RW. (normally both, but you still see some +RW or -RW only units from time to time)

Please correct me if i’m saying something false.

I’ve learned and heared that RAM DVDs can only be read in the drive where they were writed.

If this were true, it would be a disadvantage for this format.

I have not had that problem with DVD-RAMs. Though I only have two drives to test with. In generally there isn’t a problem, so long as the drive supports DVD-RAM. Drives that support DVD-RAM are rare though, you might be thinking of that situation.

Nothing much to say. A 4 pages blurb sponsored by DVD-RAM companies with
outdated informations. Only 2 pages actually discuss defect management,
and in total only 15 lines are devoted to -RW and +RW technologies.
A “study” which would have been better released on April 1st.

Full quote:

Press Release Source: RAM Promotion Group

Study Reveals DVD-RAM Drives Provide Most Secure Defect Management Solution Available Today
Tuesday May 25, 10:01 am ET
Media Sciences Study Identifies Flaws of Current +RW Defect Management Options

NEW YORK, May 25 /PRNewswire/ – A new DVD defect management study, conducted by Media Sciences, Inc., and sponsored by the RAM Promotion Group (RAMPRG), reveals that DVD-RAM drives provide the most robust, drive-based defect management among currently available recordable DVD formats. An optional protective cartridge offers even greater protection and reliability for DVD-RAM.
A new whitepaper, Defect Management Capabilities of Various DVD Technologies by Media Sciences, an internationally recognized, independent testing laboratory, outlines an investigation into three formats of rewritable DVD drives and media including DVD-RAM, DVD-RW and +RW. The investigation focused on overall defect management, compatibility, media defect and error detection/correction, and looked to identify the pros and cons of defect management currently available to users.

“With so many recordable DVD formats available, we wanted to investigate the current differences in defect management technology,” said Dr. Jerome L. Hartke, President, Media Sciences, Inc. “What we found is that while no two devices or media are the same, DVD-RAM currently offers the best available defect management for rewritable DVD applications.”

The study focused on the two different drive-based defect management methods – slipping and linear replacement. Slipping works by marking a defect and sequentially moving data to the next good region. By contrast, linear replacement marks the defect and moves data to a non-contiguous, designated spare area.

The study finds that DVD-RAM, which employs both slipping and linear replacement, offers a high level of data integrity on full random access media. By marking the defect and finding the best-allocated area for continuous recording, DVD-RAM allows users to have a higher level of confidence in data storage and retrieval.

“Defect management is one of the key functionalities that has led RAM Promotion Group member companies to support the DVD-RAM format,” said Tony Jasionowski, Executive Technology Director, RAMPRG and Senior Group Manager, Panasonic Technologies Company. “DVD-RAM supports a powerful, drive-based defect management system that has been available for more than 5 years. This, coupled with all of the features that DVD-RAM media and product offer, make it the best choice for DVD recording today and for the future.”

In addition, the study showed that while other media formats employ some defect management capabilities, they don’t deliver across the board. For example, DVD-RW drives flag, but do not replace defective sectors and are designed more for sequential recording, such as streaming A/V. Therefore, because drive-based defect replacement is not available, the study finds that DVD-RW disks may not be suitable for computer data storage. The study notes that standards for +RW media do not define a defect management system, but instead defer to a future planned Mount Rainier standard (+MRW) that is drive-based and requires a compliant write drive and recording system. +MRW awaits planned recording drive and operating system support.

Beyond detecting errors and relocating data to a defect-free area, the study determined that defect management can also compensate for the gradual degradation of the media that is a normal result of repeated overwrite cycles. This protection, and a unique recording layer and randomization of overwrite locations on DVD-RAM, adds to the longevity of the media which allows over 100,000 overwrite cycles.

The full whitepaper can be viewed at:
U.S.:   http://www.ramprg.com/FileUploads/MediaSciences_WhitePaper.pdf;.
or..    http://www.mscience.com/pub.html#TECH
Europe: http://europe-ramprg.com/FileUploads/MediaSciences_WhitePaper.pdf

About the RAM Promotion Group (RAMPRG):

Formed by nine companies in 2003 – Hitachi, Ltd., Hitachi-LG Data Storage, Inc., Hitachi Maxell, Ltd., LG Electronics Inc., Matsushita Electric Industrial Co., Ltd. (Panasonic), Samsung Electronics Co., Ltd., TEAC Corporation, Toshiba Corporation and Victor Company of Japan, Limited (JVC) - the RAM Promotion Group is dedicated to promoting the DVD-RAM format and popularizing DVD-RAM related products on an international basis. The RAMPRG collaborates with the Recordable DVD Council (RDVDC), and all of the founding members of the RAMPRG are also members of the RDVDC.

For additional information on the RAMPRG and the DVD-RAM format, please visit the organization’s dedicated Web site at http://www.ramprg.com .

Source: RAM Promotion Group

RDVDC is one of the main business groups promoting DVD-RAM and DVD-R. The PR itself is also outdated.

DVD-RW Defect Management

DVD-RW drives flag but do not replace defective sectors. The R-Information zone that precedes lead-in contains a Recording Management Area consisting of a Power Calibration Area followed by a Defect Status Bitmap. Every ECC block is represented in the bitmap that results from optional certification by the manufacturer or is optionally updated when the disc is reformatted. DVD-RW is designed for sequential recording, such as streaming A/V. Although conventional DVD-Video players cannot access the Defect Status Bitmap, many A/V applications are not sensitive to defective sectors. Because drive-based defect replacement is not available, DVD-RW discs may not be suitable for computer data storage. Software-based defect management could be provided by UDF.

+RW Defect Management

Standards for +RW media do not define a defect management system, but instead defer to a future planned Mount Rainier standard (MRW) that is drive-based and requires a compliant write drive and recording system. Although CD-MRW drives are currently available, +MRW awaits planned recording drive and operating system support. Because there is no current +MRW specification, legacy drives may subsequently have compatibility problems. In the interim, a software-based UDF defect management system can be used with +RW.