6:4654 with SMTP id 956f58d0204a3-63fb3b64794mr4312937d50.35.1762203488831; Mon, 03 Nov 2025 12:58:08 -0800 (PST) Received: from mail-yw1-f173.google.com (mail-yw1-f173.google.com. [209.85.128.173]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-63fc95a249bsm33837d50.14.2025.11.03.12.58.07 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Nov 2025 12:58:07 -0800 (PST) Received: by mail-yw1-f173.google.com with SMTP id 00721157ae682-7866e9e62e1so18085797b3.2 for ; Mon, 03 Nov 2025 12:58:07 -0800 (PST) X-Forwarded-Encrypted: i=1; AJvYcCWQfKX9FSzS/+pU4X46BTKR5Q1GeIiZLkko4rOXZtPQn/8nGe370Nl/ZVSGkPFNAd0egZ472FjYY16cZjJ7oik=@freebsd.org X-Received: by 2002:a05:690c:6f92:b0:786:87b1:9631 with SMTP id 00721157ae682-78687b19a0amr26204277b3.66.1762203487302; Mon, 03 Nov 2025 12:58:07 -0800 (PST) List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@FreeBSD.org MIME-Version: 1.0 References: <8B8086D4-C68D-4C8A-86F2-C35212823B94@ketas.si.pri.ee> <73b4a16d-30f3-44b6-8477-aaa8e5aff82a@gmail.com> <20251103181232.3d7c8825415f1d2ad3f08c6e@dec.sakura.ne.jp> <20251104032244.f9fbf3cf8d67897a0ea84ac0@dec.sakura.ne.jp> In-Reply-To: <20251104032244.f9fbf3cf8d67897a0ea84ac0@dec.sakura.ne.jp> From: Tomek CEDRO Date: Mon, 3 Nov 2025 21:57:55 +0100 X-Gmail-Original-Message-ID: X-Gm-Features: AWmQ_bnNsQReVDqFlMJibllCJNbLq6bH7UL60NyoNx3dbzpjCgmmI0u8VPQbHgo Message-ID: Subject: Re: Why is the DVD image so large? To: Tomoaki AOKI Cc: Sulev-Madis Silber , freebsd-current@freebsd.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Queue-Id: 4d0kSk6vjvz3SRq On Mon, Nov 3, 2025 at 7:22=E2=80=AFPM Tomoaki AOKI wrote: > On Mon, 3 Nov 2025 18:32:59 +0100 > Tomek CEDRO wrote: > > > On Mon, Nov 3, 2025 at 6:06=E2=80=AFPM Sulev-Madis Silber > > 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 securi= ty 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 =3D 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 --=20 CeDeROM, SQ7MHZ, http://www.tomek.cedro.info