From nobody Mon Nov 03 18:22:44 2025 X-Original-To: freebsd-current@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4d0g1V1Qqhz6FDcT for ; Mon, 03 Nov 2025 18:22:54 +0000 (UTC) (envelope-from junchoon@dec.sakura.ne.jp) Received: from www121.sakura.ne.jp (www121.sakura.ne.jp [153.125.133.21]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4d0g1T43Pbz3xX0 for ; Mon, 03 Nov 2025 18:22:53 +0000 (UTC) (envelope-from junchoon@dec.sakura.ne.jp) Authentication-Results: mx1.freebsd.org; none Received: from kalamity.joker.local (124-18-6-240.area1c.commufa.jp [124.18.6.240]) (authenticated bits=0) by www121.sakura.ne.jp (8.18.1/8.17.1/[SAKURA-WEB]/20201212) with ESMTPA id 5A3IMiAC097985; Tue, 4 Nov 2025 03:22:45 +0900 (JST) (envelope-from junchoon@dec.sakura.ne.jp) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=dec.sakura.ne.jp; s=s2405; t=1762194166; bh=AOBqE6jnkMulc/u71tIVlO+uS8N/fIEKSGadIfgE7WM=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=ZA0JWcNmMOeERud9uM0JQG3SahQidLgifbhJ8eTw/WJdIiYBrOqX4Z6TSEgGtAnki 1Ewt7Lw/7v38eObDZERN1g152Txyw+9Nb/edGbZ2yHl+ESLAVztrXCQd/+FHFIJlnR dUxgVRCLuTIsLcPgzXKOWzM/eqDKyDDcNAcY/DKA= Date: Tue, 4 Nov 2025 03:22:44 +0900 From: Tomoaki AOKI To: Tomek CEDRO Cc: Sulev-Madis Silber , freebsd-current@freebsd.org Subject: Re: Why is the DVD image so large? Message-Id: <20251104032244.f9fbf3cf8d67897a0ea84ac0@dec.sakura.ne.jp> In-Reply-To: References: <8B8086D4-C68D-4C8A-86F2-C35212823B94@ketas.si.pri.ee> <73b4a16d-30f3-44b6-8477-aaa8e5aff82a@gmail.com> <20251103181232.3d7c8825415f1d2ad3f08c6e@dec.sakura.ne.jp> Organization: Junchoon corps X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; amd64-portbld-freebsd15.0) 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 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:7684, ipnet:153.125.128.0/18, country:JP] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Queue-Id: 4d0g1T43Pbz3xX0 On Mon, 3 Nov 2025 18:32:59 +0100 Tomek CEDRO wrote: > On Mon, Nov 3, 2025 at 6:06 PM 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 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 > 3. no electronics parts = immune to esd / emp like ssd. > 4. long life time far exceeding hdd/ssd (i.e. hard coat, or mdisk). > 5. small and light. > > -- > CeDeROM, SQ7MHZ, http://www.tomek.cedro.info -- Tomoaki AOKI