From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 9393 invoked from network); 1 Jan 2024 00:26:22 -0000 Received: from minnie.tuhs.org (2600:3c01:e000:146::1) by inbox.vuxu.org with ESMTPUTF8; 1 Jan 2024 00:26:22 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 4981C43EC3; Mon, 1 Jan 2024 10:26:18 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tuhs.org; s=dkim; t=1704068778; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references:list-id:list-help:list-owner:list-unsubscribe: list-subscribe:list-post; bh=V73QL5qYm1i87YG+dOpDCEYToo4Num3bngeDoXcyQdA=; b=PLILa4Sj9Q0i5UaQDbdfgtMfTVoh4piZw8NU4xej3JdKBpcZsO4S2uqV4owy0cwLek+VQN qJWcPyBkOU1vKkyMwBIK+yQlY/mF5HhCvT3x7GxiqSpQDv1OhKZn4hel+lYh9bIQMPybSa rJ1iUDZ/nnmoZD6QO0B/9D8Tcj5H6Jw= Received: from tncsrv06.tnetconsulting.net (tncsrv06.tnetconsulting.net [IPv6:2600:3c00:e000:1e9::8849]) by minnie.tuhs.org (Postfix) with ESMTPS id D73EA43EC2 for ; Mon, 1 Jan 2024 10:26:13 +1000 (AEST) Received: from Contact-TNet-Consulting-Abuse-for-assistance by tncsrv06.tnetconsulting.net (8.15.2/8.15.2/Debian-3) with ESMTPSA id 4010QD3j016989 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO) for ; Sun, 31 Dec 2023 18:26:13 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tnetconsulting.net; s=2019; t=1704068773; bh=V73QL5qYm1i87YG+dOpDCEYToo4Num3bngeDoXcyQdA=; h=Message-ID:Date:MIME-Version:User-Agent:Subject:Content-Language: To:References:From:In-Reply-To:Content-Type:Cc:Content-Disposition: Content-Language:Content-Transfer-Encoding:Content-Type:Date:From: In-Reply-To:Message-ID:MIME-Version:References:Reply-To: Resent-Date:Resent-From:Resent-To:Resent-Cc:Sender:Subject:To: User-Agent; b=1tjykBBDNxEaxIjbpAVrYP4pbF0ZHpP/KkswKDCMMvmGSw3CGDf6xQIwz8lxMXpDp 2k9HjmtepQbws7YvvQV01l+c6vbC8znQSZYkPdAQ2Gxv3K24i1/yM+LoaVciM03NdR qqMW8ZUT8OTMZFk+tZlmfAe5n3G7Uk7f7IwmrfW4= Message-ID: Date: Sun, 31 Dec 2023 18:26:12 -0600 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US To: tuhs@tuhs.org References: <6470c59f-a1e5-418f-803d-76bcd761f530@tnetconsulting.net> <202312311738.3BVHctA1018336@freefriends.org> In-Reply-To: <202312311738.3BVHctA1018336@freefriends.org> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="------------ms070602020408080306090401" Message-ID-Hash: S65NXQYSZAORM2XCKPUQG7VQ63JHXHME X-Message-ID-Hash: S65NXQYSZAORM2XCKPUQG7VQ63JHXHME X-MailFrom: gtaylor@tnetconsulting.net X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: Question about BSD disklabel history List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: From: Grant Taylor via TUHS Reply-To: Grant Taylor This is a cryptographically signed message in MIME format. --------------ms070602020408080306090401 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/31/23 11:38, arnold@skeeve.com wrote: > The different overlapping partitions predates disk labels. Okay. That in and of itself doesn't surprise me much that a convention of overlapping partitions was carried forward from the driver based partitioning into label based partitioning. > Up to and including 4.3 BSD, to change the size of partitions on a > particular disk, you had to recompile the kernel. So I've learned over the last couple of years as I read more about Unix history. > They were that way so that if you had multiple disks, you could use > one for root + swap + some thing small and use another whole disk > for a single filesystem. I'm not understanding how /overlapping/ partitions helps make use of portions of disks. Maybe I should back up and ask for clarification. What /overlapping/ partitions means in this context? My naive assumption was that partition -- I use that term loosely -- "c" overlaps / contains / all other partitions on the disk; "a", "b", and maybe "d". I'm eliding the "c" MBR partition vs "d" entire drive" distinction for the moment. I see some value in the "c" partition being the entire disk as used by BSD so that it's possible to point backup / restore / copy utilities at the entire disk. But I don't understand value in having partitions overlap / contain each other's blocks, save for backup via "c". I do see some value in extending the "c" is the entire MBR partition methodology to "d" is the entire disk containing multiple MBR partitions. Again, the value seems to be in backup and recovery. But I still simply do not understand why I would ever want partition "e" to be blocks 100-199, partition "f" to be blocks 195-299, and partition "g" to be blocks 295-399. What value is there in having partitions e, f, and g overlap each other? I get dd if=/dev/0c of=/dev/rmt. Or even /dev/0d. I fail to understand why I'd ever want other partitions to overlap. > It was also helpful, if you had the drives, to nightly dd your real > root to the "a" partition on another, identical drive, so that you > could boot the backup root in an emergency. Sure. But I don't see what that has to do with overlapping partitions. I'd naively think that I could do something like the following: dd if=/dev/0a of=/dev/1a And get the same effect. > I am guessing that the original conventions date back to V7 or 32V, > but one would have to go looking at code to be sure. "a" for root makes some intuitive sense as the root file system is required to do anything else. Then when you want swap, the next partition is "b". Wanting another partition that is the entire disk (as seen by BSD) makes some logical sense to me too, so "c". Were subsequent partitions sort of used as needed and had less consistency? Especially when "d" because the entire disk containing multiple MBR partitions when "c" was restricted to the MBR partition the label was in? Aside: Would that mean that the following "d" partitions would be the same thing, as in the entire /dev/ad0 disk? /dev/ad0s0d /dev/ad0s1d Wherein I'm borrowing the FreeBSD slice nomenclature -- as I understand it -- to identify the first (zero) and second (one) MBR partition on /dev/ad0 History and how we got to where we are today can be both very confusing and even more enlightening once you understand it. What's more is that once you understand it, things start making more intuitive sense when you look at them. -- Grant. . . . --------------ms070602020408080306090401 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCC C0owggUyMIIEGqADAgECAhEA0VX8K1B6bsGDH67kXwHPWzANBgkqhkiG9w0BAQsFADCBljEL MAkGA1UEBhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2Fs Zm9yZDEYMBYGA1UEChMPU2VjdGlnbyBMaW1pdGVkMT4wPAYDVQQDEzVTZWN0aWdvIFJTQSBD bGllbnQgQXV0aGVudGljYXRpb24gYW5kIFNlY3VyZSBFbWFpbCBDQTAeFw0yMzExMTIwMDAw MDBaFw0yNDExMTEyMzU5NTlaMCsxKTAnBgkqhkiG9w0BCQEWGmd0YXlsb3JAdG5ldGNvbnN1 bHRpbmcubmV0MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzOnBjTJUlBTzN81c PlYErJc9kEbTI/hXq0NA6ZoG4VM6puYTEXtITANjgX+NRwwHjldESnC8dvh6Mx5ckEk9sWoD 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