I'll shift the subject/content a bit. Has DVD dual-layer/double-layer all but disappeared? Not only does Staples (etc) hardly carry the blanks anymore, but there are almost no CD/DVD burners on the market anymore (at least not at reasonable prices) that do DVD dual-layer/double-layer (-R or +R). I didn't see the trend; I must have been asleep at the switch, so it caught me by total surprise when I ordered several portable CD/DVD drives for connecting to today's laptops. Hey, at least they are low-power enough to require only one USB port, unlike a pair of ASUS CD/DVD drives I have that demand two USB ports (for power) Hartmut W Sager On Tue 24 Mar 2026 at 09:45:10 -05:00, Adam Thompson <athompso@athompso.net> wrote:

A CD-R/RW/DVD-R/RW device is not a normal random-access writable device. You cannot simply write bits to it the same way you write bits to an HDD or SSD.

The special burning programs (e.g. wodim) first send commands to the drive to find out what kind of disc is in there, and once that's known, they send special commands to prepare the drive for writing, then sends the data in a particular format via a special interface, then finally sends the commands to the drive to have it write out the correct track padding and postamble.

There are several burning modes you can use to create a disc from an ISO file; normally it doesn't matter very much, you should be able to go with whatever your drive or burning program uses by default.

If wodim et al complain the disc in the drive is read-only, that's because it is. Or at least your drive thinks it is.

Make sure you do in fact have a drive capable of writing the size of ISO onto the type of disc you have, and if that all checks out, just throw the first disc away and use a new one.

There are hundreds, probably thousands, of guides to burning discs on the Internet - even at the end of the physical media era, it could still be pretty complicated depending on what you were burning in what format to what kind of media using what kind of drive with what program. You're in for a bunch of reading to figure this all out, I'm afraid.

-Adam

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*From:* Tait Palsson <votetaitpalsson@protonmail.com> *Sent:* Monday, March 23, 2026 5:06:58 PM *To:* roundtable@muug.ca <roundtable@muug.ca> *Subject:* [RndTbl] Roundtable

Hello MUUG Roundtable,

Is it just me or is it impossible to burn a .iso to an optical disc?

I have tried with dd, various iso writers on various distributions but these either grey out or do not list the target device, and with multiple pieces of hardware. I am always met with an error that the media is read-only when the disc drive is read and write. I also tried /dev/sr0 and its alias /dev/cdrom but nothing different happened.

An internet search tells me that special software like wodim, growisofs, or Brasero could be needed. Why and is this just me?

If dd did work I imagine that I could use bs= to bring down the write speed and improve accuracy.

Sincerely, Tait

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Back on the original thread, correct me if I'm wrong but isn't the .iso file already in the correct raw format to be burned on the disk? I haven't done it in a long while but back when the main way to build a linux distro was to boot from CD/DVD, I used to just use "dd if=/my/file/distro.iso of=/dev/cdrom" and I don't recall ever having an issue with that. I somehow threw away the computer chassy that had my last dvd drive in it so I can't even test this theory anymore... On Tue, Mar 24, 2026 at 9:45 AM Adam Thompson <athompso@athompso.net> wrote:

A CD-R/RW/DVD-R/RW device is not a normal random-access writable device. You cannot simply write bits to it the same way you write bits to an HDD or SSD.

The special burning programs (e.g. wodim) first send commands to the drive to find out what kind of disc is in there, and once that's known, they send special commands to prepare the drive for writing, then sends the data in a particular format via a special interface, then finally sends the commands to the drive to have it write out the correct track padding and postamble.

There are several burning modes you can use to create a disc from an ISO file; normally it doesn't matter very much, you should be able to go with whatever your drive or burning program uses by default.

If wodim et al complain the disc in the drive is read-only, that's because it is. Or at least your drive thinks it is.

Make sure you do in fact have a drive capable of writing the size of ISO onto the type of disc you have, and if that all checks out, just throw the first disc away and use a new one.

There are hundreds, probably thousands, of guides to burning discs on the Internet - even at the end of the physical media era, it could still be pretty complicated depending on what you were burning in what format to what kind of media using what kind of drive with what program. You're in for a bunch of reading to figure this all out, I'm afraid.

-Adam

Get Outlook for Android <https://aka.ms/AAb9ysg> ------------------------------ *From:* Tait Palsson <votetaitpalsson@protonmail.com> *Sent:* Monday, March 23, 2026 5:06:58 PM *To:* roundtable@muug.ca <roundtable@muug.ca> *Subject:* [RndTbl] Roundtable

Hello MUUG Roundtable,

Is it just me or is it impossible to burn a .iso to an optical disc?

I have tried with dd, various iso writers on various distributions but these either grey out or do not list the target device, and with multiple pieces of hardware. I am always met with an error that the media is read-only when the disc drive is read and write. I also tried /dev/sr0 and its alias /dev/cdrom but nothing different happened.

An internet search tells me that special software like wodim, growisofs, or Brasero could be needed. Why and is this just me?

If dd did work I imagine that I could use bs= to bring down the write speed and improve accuracy.

Sincerely, Tait

_______________________________________________ Roundtable mailing list -- roundtable@muug.ca To unsubscribe send an email to roundtable-leave@muug.ca

-- John Lange

On 2026-03-29 Adam Thompson wrote:

Not being about to do that in the first place was why tools like cdrecord, cdrdao, wodim, et al. came into existence. -Adam

Ya, I think Adam's right. I'm probably the guy who burns the most optical in the club -- just passed my 2000th backup disc, and do maybe 125-150 a year. I've never seen dd just work for this. cdrecord does a bucketload of stuff before/during burning, as you'll see if you use the -v option. For write-once -R media the magic is: cdrecord -v dev=/dev/sr0 speed=16 -dao my.iso To be extra careful, you can lower the speed to 8 or 4. Going slower is sometimes *less* reliable with modern drives though. I find about 1 in 40 discs is a dud: often due to visible flaw/damage, but sometimes just for no reason at all. I also find drives will sometimes go nutso after 50-80 straight burns and will burn 100% coasters until an actual full computer reset. And eventually they just die for writing... For +R media you have to use the growisofs, and for -RW media you need to use cdrecord to format it first. I use -R 99% of the time. I don't think the market is dying just yet as right now the comp wholesalers still have like 10 brands to choose from. Clearly there are still uses for it. As for USB replacing it: not if cost is a factor. I still have optical at ~4c a GB. AI says the cheapest USB sticks will be around 20c a GB, or 5X more. It is getting closer, though! And being able to re-use 5-10 years later has some appeal... unless the flash is all dead for writing after 10 years? Not as easy to put 50 of them on a spindle for storage, though! :-) And DVD-DL: yes, appears to be gone :-( I bought a tiny amount of media thinking I'd get a drive when the prices dropped, and instead the drives just disappeared. BluRay writable appears to have killed it, and those are still an option, though getting a non-USB drive may be tricky. If anyone has a drive that can burn DL I'll sell you some media cheap! Or trade for -R's I can actually use. Cool, there appears to be a 100GB/disc format now -- but $/GB is worse than USB.

Might want to buy those right away then... Ah crap apologies for the Google links, working on my phone. -Adam Japanese firm stops production of Blu-ray disc drives — Buffalo says there will be no successors to its current trio of portable USB-attached drives [Updated] | Tom's Hardware https://share.google/a6pjGqwHeL8RTy30M Another major Japanese electronics firm exits the Blu-ray market — Elecom publishes notice of termination of all external drives | Tom's Hardware https://share.google/FG9LuTIFYF60CEt8n Get Outlook for Android<https://aka.ms/AAb9ysg> ________________________________ From: Trevor Cordes <trevor@tecnopolis.ca> Sent: Tuesday, March 31, 2026 9:16:47 PM To: roundtable@muug.ca <roundtable@muug.ca> Subject: [RndTbl] Re: Roundtable Optical Burning Followup: it appears the BD-writers (BluRay) can write dual-layer DVD, so there's one solution. Drives are available under $200, though brand options are limited. At least I've found a SATA one, as well as the ubiquitous USB ones. Who knows how well the Linux writing software has been updated to support this stuff... _______________________________________________ Roundtable mailing list -- roundtable@muug.ca To unsubscribe send an email to roundtable-leave@muug.ca