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From: jdow <jdow@earthlink.net>
To: Martin Steigerwald <martin@lichtvoll.de>
Cc: Michael Schmitz <schmitzmic@gmail.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Matthew Wilcox <willy@infradead.org>,
	David Sterba <dsterba@suse.cz>,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Jens Axboe <axboe@kernel.dk>,
	linux-m68k <linux-m68k@lists.linux-m68k.org>
Subject: Re: Amiga RDB partition support for disks >= 2 TB
Date: Thu, 28 Jun 2018 05:31:18 -0700
Message-ID: <6b25bd4b-d218-55a0-6687-b17fbf7e5c97@earthlink.net> (raw)
In-Reply-To: <51008870.LIDn3ZZdjm@merkaba>

On 20180628 04:38, Martin Steigerwald wrote:
> Martin Steigerwald - 28.06.18, 13:30:
>> jdow - 28.06.18, 12:00:
>>> On 20180628 01:16, Martin Steigerwald wrote:
>> […]
>>
>>>>> That brings to the fore an interesting question. Why bother with
>>>>> RDBs
>>>>> over 2TB unless you want a disk with one single partition? This
>>>>> Win10
>>>>> monster I am using has a modest BIOS driver partition for the OS
>>>>> and
>>>>> a giant data partition. That smaller partition would easily work
>>>>> with
>>>>> any RDB/Filesystem combination since 2.0. So there are some good
>>>>> workarounds that are probably "safer" and at least as flexible as
>>>>> RDBs, one Linux has used for a very long time, too.
>>>>
>>>> Well, my use case was simple:
>>>>
>>>> I had this 2 TB disk and I choose to share it as a backup disk for
>>>> Linux *and* AmigaOS 4.x on that Sam440ep I still have next to me
>>>> desk here.
>>>
>>> EEEEEEK! The hair on my neck is standing up straight! Have you heard
>>> of SAMBA? The linux mail server firewall etc machine has an extra
>>> 4TB
>>> disk on it as a backup for the other systems, although a piddly 4TB
>>> is small when I save the entire 3G RAID system I have. It's a proof
>>> of concept so.... A full backup on a 1gig Ethernet still takes a
>>> looooong time. But backing up even an 18GB disk on an Amiga via
>>> 100Base-t isn't too bad. And disk speeds of the era being what they
>>> were it's about all you can do anyway.
>>
>> Heh, the thing worked just fine in Amiga OS 4. I got away with it
>> without an issue, until I plugged the disk to my Linux laptop and
>> wrote data onto the Linux file system. Mind you, I think in that
>> partition marked LNX\0 I even created a Linux LVM with pvcreate. Do
>> you call that insane? Well it probably is. :)
>>
>> And as an Amiga user I could just return to you: I clicked it, it did
>> not warn, so all is good :)
>>
>> But yeah, as mentioned I researched the topic before. And I think
>> there
>> has not even been an overflow within the RDB:
>>> The raw, theoretical limit on the maximum device capacity is about
>>> 2^105 bytes:
>>>
>>> 32 bit rdb_Cylinders * 32 bit rdb_Heads * 32 bit rdb_Sectors * 512
>>> bytes/sector for the HD size in struct RigidDiskBlock
>>
>> http://wiki.amigaos.net/wiki/RDB_(Amiga_Rigid_Disk_Block)
>>
>> Confirmed by:
>>
>> The .ADF (Amiga Disk File) format FAQ:
>> http://lclevy.free.fr/adflib/adf_info.html#p6
>>
>> But what do I write, you know the RDB format :)
>>
>> So just do the calculation in 96 Bit and you all are set :)
> 
> For sectors.
> 
> Or
> 
> 3*32+9 (for 512 bytes per sector) = 105 bits
> 
> for bytes.
> 
>> Now that is a reason for 128 Bit CPUs :).
>>
>> Muuhahaha.

And if you make the logical block size 65536 you need 128 bits or 10^something 
big = 2^128.
{^_-}

  reply index

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-25 15:46 Moving unmaintained filesystems to staging Matthew Wilcox
2018-04-25 15:47 ` Christoph Hellwig
2018-04-25 20:30 ` David Sterba
2018-04-26  2:57   ` Matthew Wilcox
2018-04-26 10:28     ` moving affs + RDB partition support to staging? (was: Re: Moving unmaintained filesystems to staging) Martin Steigerwald
2018-04-26 10:45       ` moving affs + RDB partition support to staging? John Paul Adrian Glaubitz
2018-04-26 10:59         ` David Sterba
2018-04-26 11:06           ` John Paul Adrian Glaubitz
2018-05-06  0:59         ` Al Viro
2018-05-06  7:40           ` Al Viro
2018-05-06 20:46             ` Al Viro
2018-05-06 20:49               ` John Paul Adrian Glaubitz
2018-05-06 21:32               ` Al Viro
2018-05-07  2:15                 ` Al Viro
2018-05-07  2:40                   ` Michael Schmitz
2018-05-07  7:08                     ` Martin Steigerwald
2018-05-07 20:50                       ` Michael Schmitz
2018-05-07 20:56                         ` Ingo Jürgensmann
2018-05-07 20:58                           ` John Paul Adrian Glaubitz
2018-05-06  8:40           ` John Paul Adrian Glaubitz
2018-05-06 10:12           ` Martin Steigerwald
2018-04-26 11:00       ` moving affs + RDB partition support to staging? (was: Re: Moving unmaintained filesystems to staging) Christoph Hellwig
2018-04-26 11:08       ` Geert Uytterhoeven
2018-04-26 23:56         ` Finn Thain
2018-04-27  1:43           ` moving affs + RDB partition support to staging? jdow
2018-04-27  1:26         ` jdow
2018-05-06  8:52           ` John Paul Adrian Glaubitz
2018-05-06 10:10             ` Martin Steigerwald
2018-05-07  4:54             ` jdow
2018-04-27  2:11         ` moving affs + RDB partition support to staging? (was: Re: Moving unmaintained filesystems to staging) Michael Schmitz
2018-06-24  9:06           ` Martin Steigerwald
2018-06-24 11:33             ` moving affs + RDB partition support to staging? jdow
2018-06-24 11:40             ` jdow
2018-06-26  2:23               ` Michael Schmitz
2018-06-26  5:17                 ` jdow
2018-06-26  8:12                   ` Martin Steigerwald
2018-06-26  9:46                     ` jdow
2018-06-26  8:31                   ` Michael Schmitz
2018-06-26  9:45                     ` jdow
2018-06-27  1:07                       ` Michael Schmitz
2018-06-27  6:24                         ` jdow
2018-06-27  8:03                           ` Martin Steigerwald
2018-06-28  2:57                             ` jdow
2018-06-28  7:40                               ` Amiga RDB partition support for disks >= 2 TB (was: Re: moving affs + RDB partition support to staging?) Martin Steigerwald
2018-06-27  9:00                           ` moving affs + RDB partition support to staging? Michael Schmitz
2018-06-28  3:44                             ` jdow
2018-06-28  5:43                               ` Michael Schmitz
2018-06-28  6:39                                 ` jdow
2018-06-28  8:16                                   ` Amiga RDB partition support for disks >= 2 TB (was: Re: moving affs + RDB partition support to staging?) Martin Steigerwald
2018-06-28 10:00                                     ` Amiga RDB partition support for disks >= 2 TB jdow
2018-06-28 11:30                                       ` Martin Steigerwald
2018-06-28 11:38                                         ` Martin Steigerwald
2018-06-28 12:31                                           ` jdow [this message]
2018-06-28  8:07                                 ` Amiga RDB partition support for disks >= 2 TB (was: Re: moving affs + RDB partition support to staging?) Martin Steigerwald
2018-06-27  7:57                         ` moving affs + RDB partition support to staging? Martin Steigerwald
2018-06-28  2:56                           ` jdow
2018-06-26  8:02                 ` Martin Steigerwald
2018-06-26  8:40                   ` Michael Schmitz
2018-06-26  9:31                   ` jdow
2018-06-25  7:53             ` moving affs + RDB partition support to staging? (was: Re: Moving unmaintained filesystems to staging) Michael Schmitz
2018-06-25  8:26               ` Martin Steigerwald
2018-06-25  8:40               ` Geert Uytterhoeven
2018-04-27  8:01         ` Martin Steigerwald
2018-04-26  4:58   ` Moving unmaintained filesystems to staging Nikolay Borisov
2018-04-26  5:30     ` Willy Tarreau
2018-04-26  6:11 ` Pavel Machek
2018-04-26 10:36   ` Martin Steigerwald
2018-05-03  9:18     ` Pavel Machek
2018-04-27  1:10   ` Luis R. Rodriguez
2018-04-29 12:07   ` Greg KH
2018-04-29 20:07     ` Ondrej Zary
2018-04-29 23:37       ` Greg KH
2018-05-01 10:14         ` Pavel Machek

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