On Mon, Nov 3, 2025 at 7:22 PM Tomoaki AOKI <[email protected]> wrote: > On Mon, 3 Nov 2025 18:32:59 +0100 > Tomek CEDRO <[email protected]> wrote: > > > On Mon, Nov 3, 2025 at 6:06 PM Sulev-Madis Silber > > <[email protected]> wrote: > > > (..) > > > the optical disks are most of cases readonly, they could retain data > > > well, could be pressed into permanent disk, would be allowed in high > > > security environments where usb would be not maybe > > > > > > i miss the optical use cases here, anyone give me insight? > > > > 1. read only / immutable. > > Some types of optical disks are re-writable, while most of writable > optical disks are write-once. > > And re-writable disks are roughly categorized into two. > > a) Erase and write for the whole disk at once. > (Example: CD-RW and DVD-RW) > b) Can read/write just like a HDD. > (Example: MO, PD, DVD-RAM) > > IIRC, DVD-RAM needed to be formatted and written as UDF, > while MO and PD were mimic'ing HDD and partitionable. > > > 2. no moving parts = immune to mechanical malfunction like hdd. > > MO, PD and some of DVD-RAM media are provided as "cartridges" > and had shutter on access hole. > https://en.wikipedia.org/wiki/Magneto-optical_drive > https://en.wikipedia.org/wiki/Phase-change_Dual > https://en.wikipedia.org/wiki/DVD-RAM
Okay, so I found our local optical disk magician (mr. hocuspocus lol), and he said "DVD-RAM DL disks never existed. JVC made DVD-RW DL but they never reached the market". So the easiest way is to just get a bunch of DVD-R DL double layer one time writable which are easily available and cheap.. or a BD-RE disk :-) On the other hand I found this on wikipedia (https://en.wikipedia.org/wiki/DVD-RAM) about DVD-RAM "Holds more data when using Double Sided discs than dual-layer DVD+RW and DVD-RW - 9.4GB for DVD-RAM vs 8.5GB for DVD+RW DL and DVD-RW DL". Does that mean optical disks were also double sided not only double layer? They had to be swapped by hand just like 5.25' floppies :D Also I just found and ordered to play around: BD-RE XL (100GB rewritable Sony disk ~17EUR no enclosure) and DVD-RAM (4.7GB Panasonic disk ~5EUR no enclosure).. lets see if my recorder firmware supports them and would it be possible to just mount DVD-RAM and read-write as standard disk but slow :-P -- CeDeROM, SQ7MHZ, http://www.tomek.cedro.info
