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Explanation of Read/Write-Mechanism[edit]

Someone needs to add an explanation of how CD-RWs work to replace the one that was removed because of copyright violation. —Preceding unsigned comment added by (talk) 20:32, 1 February 2011 (UTC)

CD-RW Rewrite Cycles[edit]

It is stated in this article that the rewrite cycles of a CD-RW is 1000 times. This is the most absurd thing I have ever seen penned. The rewrite cycle depends on the media, and is typically under 100 times. With 25 times being a more reasonable amount. Understand that CD-RW is a broken technology. -- (talk) 07:16, 18 February 2009 (UTC)

Most manufaturers of CD-RW media claim around 1000 rewrite cycles. One example:

How many times can you rewrite KODAK CD-RW media? It is our understanding that the behavior of CD-RW media is that it degrades very little up to a point (~1000 rewrites) and then very rapidly after that. If you would like to be very cautious about your data, you may want to limit your use to 500 rewrite cycles

I have had poor-quality discs that become unusable after 3 or 4 writes, and others that are still good after 30ish writes, and show no sign of deterioration. (talk) 13:42, 5 April 2010 (UTC)

CD-RW as a test tool[edit]

A useful tool for constant CD-burners is using a "Test CD-RW." This can help in case a CD is apparently scratched causing a failure in performing a "clean burn." What I mean is if a CD is scratched and you don't know if that CD will perfectly burn, then you don't have to waste trying it on a CD-R. This can be a major money-saving tip as I wasted four CD-R's on a CD-ROM that looked like it was in perfect condition, but on later scrutiny I found it did contain one microscopic scratch. Just thought you might want to prepare for the worst! —Preceding unsigned comment added by (talkcontribs) 10:47, 24 July 2005 (UTC)

Generally yes, however, in practice, such a "test" CD-RW is likely to become unusable or error prone after many tests. Expect it to last considerably less than the 1000 times it's supposedly can handle. Probably even much less than a 100. So you will have to recycle those CD-RWs as well. —Preceding unsigned comment added by (talkcontribs) 09:30, 27 March 2006 (UTC)

As well as the CD-RW test tool, anouther down isde for the format is that unlike DVD+RW, they do not have random acsess to their memory, so you have to clean the entire CD before putting new files on, the same is to be said with DVD-RW. (by the way I was not signed in when I originally posted this)

  07:03, 16 January 2008 (UTC)


Is there an authoritative source for the claim that CD-R is better for archival purposes than CD-RW? I had expected the opposite to be the case. CD-R uses organic dyes that all undergo chemical decay at room temperature (some faster some slower), whereas CD-RW records data in a crystal phase transition, which is not a chemical process and should be unaffected by the slow chemical reactions at room temperature that eventually erase any dye-based CD-R. Whether a medium is rewriteable is independent of the for archivists more interesting question of how quickly the medium erases itself on the shelf! Markus Kuhn 11:40, 17 November 2005 (UTC)

Also, anyone know what temperature a CD-RW will start to melt? E.G., put your valuable data on a CD, store it in a fire safe, how hot can it get before you data is toast (no pun intended)? —Preceding unsigned comment added by (talkcontribs) 20:04, 11 March 2006 (UTC

There is no such thing as CD+RW[edit]

So don't ask "what the difference is". —Preceding unsigned comment added by (talkcontribs) 09:30, 27 March 2006 (UTC)

Faster discs in slower drives[edit]

CD-RW drives can _read_ faster rated discs recorded in faster drives, but most will not _write_ them, even at the slower speeds the drive supports. Many 4x CD-RW drives require firmware updates to avoid being damaged when a High or Ultra speed disc is inserted and attempted to be written.

Is there any reason, other than pusing sales of faster drives, to block a High speed drive from writing to 24x Ultra media at 12x?

I have an Ultra speed CD-RW/DVD-+ single layer and DVD+ dual layer burner that will only record to HP 4x-12x High speed media at 10x, not any slower nor any faster speeds. I have some Memorex 24x Ultra speed discs, but this drive will only allow 10x or 16x on it and ALWAYS FAILS verification at 16x. After writing to one of these Memorex discs 2 or 3 times at 10x, the disc will fail verification. Latest firmware on the drive. Apparently the media is iffy. I used one of these discs in a TDK High speed drive (apparently an exception to the not writing to faster discs 'rule') and it verified fine. After the Ultra speed drive failed to read it with multiple CRC errors, the TDK drive refused to erase it, then the Ultra speed drive failed to erase it and somehow damaged the disc to where nothing can be written to it.

Why would it not allow recording at all speeds the media supports? Same thing with another drive I have that supports both + and - dual layer DVD-R. It will not allow recording on CD-RW at all speeds the media supports, and the speeds it allows varies by brand.

The industry really needs to straighten this out! All CD-RW drives ought to be able to write to CD-RW media at ALL speeds a specific disc supports, and they should be able to write at slower speeds to discs with a faster top speed.

Update; I upgraded to Nero and now it will only allow those Memorex CD-RW discs to be burned at 16x or 24x (10x is not selectable) and still at both speeds they're full of CRC errors. Even weirder is the one disc that Nero and WinXP wouldn't recognize, I was able to do a full erase on, but not one of the five Memorex 24x CD-RW discs I have will record without errors.

You should get a media compatibility list from your drive manufacturer. In general, not all brands of CD-RW are supported, and not at all speeds. The 10x speed is typical of many "mid speed" CD-RW disks rated in the 4x to 12x speed range. If you get CRC errors, just change media and discard/mark the offending disks. EpiVictor 09:37, 22 August 2006 (UTC)

Criticism too biased/harsh?[edit]

I feel that the criticism subsection is somewhat biased, and to a large extent, misleading. It arbitratily mentions 2004 as a sort of "death date" for CD-RW, while they are still manufactured and sold, and compares them to flash memory based media, when their intended usage is, according to the CD Recordable FAQ, "near-line data storage" (halfway between online and offline storage, or "mid-term backups"). Also, on a reasonable quality drive, they are not that slow to read (e.g. it's not unusual to get 20x reading speed for a 10-12x CD-RW). Also, the price mentioned for CD-R, while it's surely still typical as of 2006, it was valid even a few years ago, and CD-R was always cheaper than CD-RW, so it's pointless mentioning it as a criticism. CD-RW does have its uses and it help keeping your office/disk racks free of too many test disks, and is ideal for short-to-mid term backups, much like the older tape drives. EpiVictor 09:24, 19 August 2006 (UTC)


After cleaning up the criticism section, my attention went to the speed spec section, which too appears a bit too poorly written, and somehow inaccurate:

  • CD-RW, like CD-R do have indeed hardcoded speed limits but those apply only at recording time, while reading is only limited by the drive's capability of reading CD-RW or CD-R accurately and fast enough, and the disks' overall conditions.
  • Usually, the problem is forward compatibility, not backwards compatibility: newer CD-RW drives will typically read and write any older, lower speed CD-RW format, while the opposite is generally not true, not even at reduced recording speeds.
  • Reading speed is somewhat correlated with the recording speed (e.g. a 4x CD-RW is expected to be read slower than a 24x spec one) but this is not absolute, like it's not with CD-R.

Feel free to discuss, before any changes are applied. EpiVictor 18:14, 21 August 2006 (UTC)

I have some different brands of High Speed CD-RW disks. They're all specified for 4x to 12x speed. I also have a laptop with a Panasonic UJDA710 drive that claims to be "High Speed" but has a maximum speed of only 8x. It will not write to my max 12x disks. Infra Recorder reports high speed media in a LOW SPEED drive. Who makes "High Speed" media that tops out at 8x so I can write to CD-RW faster than 4x? Brickbats to Panasonic/Matsushita/Matshita for not releasing firmware capable of writing at 8x to High Speed media with a top speed higher than that. —Preceding unsigned comment added by Bizzybody (talkcontribs) 04:12, 27 September 2008 (UTC)

Long sentence award[edit]

My vote for the longest sentence on Wiki: "This early introduction along with the lack of standards for software, file systems and disks, low recording speeds, physical incompatibility, along with the cost of the recording devices and the disks themselves back in the early 1990s, as well as the introduction of the relatively more economical CD-R disks and (especially) faster and more compact drives restricted the CD-MO to niche markets, and the format was almost forgotten, being essentially replaced by phase change CD-RW and other, better specified magneto-optical media."

Go on, take a deep breath, and try to say it.... It also doesn't actually make much sense. Colin99 21:26, 2 January 2007 (UTC) it's too long. It'd be better to do a complete rewrite of that section, and confirm at least those doubts:
  • Was it ever used commercially?
  • Did commercial "CD-MO recorders" ever exist?
  • The recording scheme was indeed, spiral-groove like CDs and modern CD-RW, or more like other MO media (which would have rendered it, in fact, totally incompatible with any CD drive, even if reading alone wasn't an issue) ?

I'll try to clear those things up, then rewrite everything as needed. EpiVictor 20:30, 3 January 2007 (UTC)

Old players[edit]

I have a player manufactured in 1988 that will read CD-RWs! Is this rare? —The preceding unsigned comment was added by (talk) 19:08, 23 January 2007 (UTC).

Sounds cool, model? EpiVictor 22:00, 23 January 2007 (UTC)

It is a Pioneer PD-4100. On cheap CD-RWs it will only play tracks past several minutes. 22:45, 23 January 2007 (UTC)

Who developed CD-RW?[edit]

In the intro paragraph, it talks about CD-RW's development, but it never specifies who developed the format. HoCkEy PUCK 22:27, 11 June 2007 (UTC)


Please improve the blanking/erasing information in this article. It says there is a choice between "full" blanking and "fast" blanking. Which software is capable of "fast" blanking? Much later, it says something quite different: 'CD-RW disks need to be blanked either entirely or "on the fly" before recording actual data'. Which software is capable of "on the fly" blanking?

Also, is there an interaction with multi-session aspects? Logically, if the disk is only partially written (with just one session) and the disk is closed (DAO?), it should not matter what else is on the disk later, so it should not all need to be erased first. But wouldn't a multi-session disk need to be fully erased first, so that the later areas were fully prepared for possible additional sessions? - (talk) 12:11, 24 April 2008 (UTC)

Blank a rewritable CD[1]

  • Display help on blanking options: cdrdao blank -h
  • Blank the disc, for example using any of the following:
o cdrdao blank --device ATA:1,0,0 --blank-mode full
o cdrdao blank --device ATA:1,0,0 --blank-mode minimal
o cdrecord dev=ATA:1,0,0 blank=fast

Jac Goudsmit, regarding formatting CD-RW media with DirectCD for Windows 2.0a: [2]
"When [Roxio] DirectCD refuses to format a CD-RW for packet-writing, it's possible that the disc is not completely blank. This may happen because you chose the "quick" option when you last erased it. The quick-erase option only erases the lead-in area to make the hardware and software think the disc is empty. This is fine if you're going to use the disc for "normal" writing as a CD-ROM, audio disc or whatever. // The packet-writing formatter in DirectCD 2.0a however (apparently) requires the disc to be totally empty, so you really have to do a full erase if the disc contained data previously. // BUT: there's another problem: after you do a full erase and shut down the program you erase with (e.g. EasyCD Pro or Easy CD Creator) it's possible that the DirectCD program won't recognize the disc as valid media, and you still won't be able to format it, until you restart the computer. // Unfortunately this means that if you want to start using a previously recorded CD-RW for packet writing, you'll have to wait a total time of at least an hour and a half for the erase and format to complete..."
- (talk) 13:24, 24 April 2008 (UTC)

Erase Function under what special format?[edit]

Most CD-RW drives today use the erase function, but under what special format? Kagemaru the Ninja of the Shadows (talk) 17:29, 6 December 2008 (UTC)--Kagemaru the Ninja of the Shadows (talk) 17:29, 6 December 2008 (UTC)

Copied + pasted?[edit]

Which came first? This article or How do rewritable CDs work?. The IEEE is a reputable source, but it may be a user generated page. So I am a bit stuck here. Can anyone shine any light in the matter? UKWikiGuy (talk) 22:43, 19 September 2010 (UTC)