RDB - Revision history

Steven Solie at 18:40, 2 October 2015

2015-10-02T18:40:57Z

← Older revision		Revision as of 18:40, 2 October 2015
Line 2:		Line 2:
	The Rigid Disk Block (RDB) is the Amiga way to store information about mass storage geometries and partitioning. Compared to the old, but still widely in used PC standard Master Boot Record (MBR) its a flexible structure with a linked list for the partitions.		The Rigid Disk Block (RDB) is the Amiga way to store information about mass storage geometries and partitioning. Compared to the old, but still widely in used PC standard Master Boot Record (MBR) its a flexible structure with a linked list for the partitions.

	It is also able to store complete ~~filesystem~~ binaries and boot code, though this is not used on AmigaOS 4 anymore.		It is also able to store complete file system binaries and boot code, though this is not used on AmigaOS 4 anymore.

	See also:		See also:
Line 9:		Line 9:

	=== Physical versus logical sizes ===		=== Physical versus logical sizes ===
	Traditionally the RDB stores physical size values like cylinders, heads and sectors. But since a long time these values do not resemble the exact physical layout of a hard disk. Instead a partitioning software like Media Toolbox chooses values that multiply to the disk size. What matters for ~~filesystem~~ etc. is the logical size, i.e. the amount of sectors a partition has and the sector size.		Traditionally the RDB stores physical size values like cylinders, heads and sectors. But since a long time these values do not resemble the exact physical layout of a hard disk. Instead a partitioning software like Media Toolbox chooses values that multiply to the disk size. What matters for file system etc. is the logical size, i.e. the amount of sectors a partition has and the sector size.

	=== Limits ===		=== Limits ===
Line 15:		Line 15:

	==== Disk size ====		==== Disk size ====
	The RDB has a quite high limit on the maximum device size, but note that currently each ~~filesystem~~ interprets the partition layout by itself.		The RDB has a quite high limit on the maximum device size, but note that currently each file system interprets the partition layout by itself.

	The raw, theoretical limit on the maximum device capacity is about 2^105 bytes:		The raw, theoretical limit on the maximum device capacity is about 2^105 bytes:

Steven Solie: spelling fixes

2012-06-19T20:36:47Z

spelling fixes

← Older revision		Revision as of 20:36, 19 June 2012
Line 2:		Line 2:
	The Rigid Disk Block (RDB) is the Amiga way to store information about mass storage geometries and partitioning. Compared to the old, but still widely in used PC standard Master Boot Record (MBR) its a flexible structure with a linked list for the partitions.		The Rigid Disk Block (RDB) is the Amiga way to store information about mass storage geometries and partitioning. Compared to the old, but still widely in used PC standard Master Boot Record (MBR) its a flexible structure with a linked list for the partitions.

	It is also able to store complete filesystem binaries and boot code, ~~tough~~ this is not used on AmigaOS 4 anymore.		It is also able to store complete filesystem binaries and boot code, though this is not used on AmigaOS 4 anymore.

	See also:		See also:
Line 9:		Line 9:

	=== Physical versus logical sizes ===		=== Physical versus logical sizes ===
	Traditionally the RDB stores physical size values like cylinders, heads and sectors. But since a long time these values do not resemble the exact physical layout of a ~~harddisk~~. Instead a partitioning software like Media Toolbox chooses values that ~~mutiply~~ to the disk size. What matters for filesystem etc. is the logical size, i.e. the amount of sectors a partition has and the sector size.		Traditionally the RDB stores physical size values like cylinders, heads and sectors. But since a long time these values do not resemble the exact physical layout of a hard disk. Instead a partitioning software like Media Toolbox chooses values that multiply to the disk size. What matters for filesystem etc. is the logical size, i.e. the amount of sectors a partition has and the sector size.

	=== Limits ===		=== Limits ===
Line 31:		Line 31:
	(with some overflow checks) should be enough, for more a math library with support for larger integers needs to be used which probably no partitioning software does.		(with some overflow checks) should be enough, for more a math library with support for larger integers needs to be used which probably no partitioning software does.

	~~But note~~: Nothing in struct RigiDiskBlock is used by the file systems for mounting the partitions, they only get the information from the struct PartitionBlock blocks, it's only a problem for the partitioning software creating the partitions correctly - as soon as there are HDs larger than 8 ZB while still using 512 bytes/sector if that ever happens.		'''Note:''' Nothing in struct RigiDiskBlock is used by the file systems for mounting the partitions, they only get the information from the struct PartitionBlock blocks, it's only a problem for the partitioning software creating the partitions correctly - as soon as there are HDs larger than 8 ZB while still using 512 bytes/sector if that ever happens.

Martin Steigerwald: /* Introduction */

2012-06-19T19:41:18Z

Introduction

← Older revision		Revision as of 19:41, 19 June 2012
Line 7:		Line 7:

	*[http://en.wikipedia.org/wiki/Amiga_Rigid_Disk_Block# Article on Wikipedia]		*[http://en.wikipedia.org/wiki/Amiga_Rigid_Disk_Block# Article on Wikipedia]
	*[http://lclevy.free.fr/adflib/adf_info.html#p6 The .ADF (Amiga Disk File) format FAQ; 6. The structure of a hard disks]

	=== Physical versus logical sizes ===		=== Physical versus logical sizes ===

Martin Steigerwald: /* Limits */

2012-06-18T20:17:57Z

Limits

← Older revision		Revision as of 20:17, 18 June 2012
Line 13:		Line 13:

	=== Limits ===		=== Limits ===
	It can store as much partitions as can fit in the reserved area for the RDB. There is no distinction between primary and logical partitions like in the Master Boot Record (MBR) standard for the PC platform.		It can store as much partitions as can fit in the reserved area for the RDB. There is no distinction between primary and logical partitions like in the Master Boot Record (MBR) standard for the PC platform.

	==== Disk size ====		==== Disk size ====

Martin Steigerwald: Physical versus logical sizes

2012-06-18T20:17:35Z

Physical versus logical sizes

← Older revision		Revision as of 20:17, 18 June 2012
Line 8:		Line 8:
	*[http://en.wikipedia.org/wiki/Amiga_Rigid_Disk_Block# Article on Wikipedia]		*[http://en.wikipedia.org/wiki/Amiga_Rigid_Disk_Block# Article on Wikipedia]
	*[http://lclevy.free.fr/adflib/adf_info.html#p6 The .ADF (Amiga Disk File) format FAQ; 6. The structure of a hard disks]		*[http://lclevy.free.fr/adflib/adf_info.html#p6 The .ADF (Amiga Disk File) format FAQ; 6. The structure of a hard disks]

			=== Physical versus logical sizes ===
			Traditionally the RDB stores physical size values like cylinders, heads and sectors. But since a long time these values do not resemble the exact physical layout of a harddisk. Instead a partitioning software like Media Toolbox chooses values that mutiply to the disk size. What matters for filesystem etc. is the logical size, i.e. the amount of sectors a partition has and the sector size.

	=== Limits ===		=== Limits ===
Line 15:		Line 18:
	The RDB has a quite high limit on the maximum device size, but note that currently each filesystem interprets the partition layout by itself.		The RDB has a quite high limit on the maximum device size, but note that currently each filesystem interprets the partition layout by itself.

	The raw limit on the maximum device capacity is about 2^105 bytes:		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		32 bit rdb_Cylinders * 32 bit rdb_Heads * 32 bit rdb_Sectors * 512 bytes/sector for the HD size in struct RigidDiskBlock

Martin Steigerwald at 20:12, 18 June 2012

2012-06-18T20:12:31Z

← Older revision		Revision as of 20:12, 18 June 2012
Line 6:		Line 6:
	See also:		See also:

	*[http://en.wikipedia.org/wiki/Amiga_Rigid_Disk_Block#Article on Wikipedia]		*[http://en.wikipedia.org/wiki/Amiga_Rigid_Disk_Block# Article on Wikipedia]
	*[http://lclevy.free.fr/adflib/adf_info.html#p6 The .ADF (Amiga Disk File) format FAQ; 6. The structure of a hard disks]		*[http://lclevy.free.fr/adflib/adf_info.html#p6 The .ADF (Amiga Disk File) format FAQ; 6. The structure of a hard disks]

Martin Steigerwald at 20:11, 18 June 2012

2012-06-18T20:11:52Z

← Older revision		Revision as of 20:11, 18 June 2012
Line 3:		Line 3:

	It is also able to store complete filesystem binaries and boot code, tough this is not used on AmigaOS 4 anymore.		It is also able to store complete filesystem binaries and boot code, tough this is not used on AmigaOS 4 anymore.

			See also:

			*[http://en.wikipedia.org/wiki/Amiga_Rigid_Disk_Block#Article on Wikipedia]
			*[http://lclevy.free.fr/adflib/adf_info.html#p6 The .ADF (Amiga Disk File) format FAQ; 6. The structure of a hard disks]

	=== Limits ===		=== Limits ===

Martin Steigerwald: moved RDB (Amiga Rigid Disk Block) to RDB: Shorter URL

2012-06-18T20:06:28Z

moved RDB (Amiga Rigid Disk Block) to RDB: Shorter URL

← Older revision		Revision as of 20:06, 18 June 2012
(No difference)

Martin Steigerwald at 20:06, 18 June 2012

2012-06-18T20:06:13Z

← Older revision	Revision as of 20:06, 18 June 2012
Line 1:	Line 1:
		== Introduction ==
		The Rigid Disk Block (RDB) is the Amiga way to store information about mass storage geometries and partitioning. Compared to the old, but still widely in used PC standard Master Boot Record (MBR) its a flexible structure with a linked list for the partitions.

		It is also able to store complete filesystem binaries and boot code, tough this is not used on AmigaOS 4 anymore.

		=== Limits ===
		It can store as much partitions as can fit in the reserved area for the RDB. There is no distinction between primary and logical partitions like in the Master Boot Record (MBR) standard for the PC platform.

		==== Disk size ====
		The RDB has a quite high limit on the maximum device size, but note that currently each filesystem interprets the partition layout by itself.

		The raw 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

		It's even much more if the sector size (rdb_BlockBytes and de_SizeBlock) is larger than 512 bytes, but AmigaOS 4.1 doesn't support anything but 512 bytes/sector HDs yet.

		==== Partition size ====
		For the partitions the maximum size is:

		32 bit (de_HighCyl + 1 - de_LowCyl) (to get the partition size) * 32 bit de_Surfaces * 32 bit de_SectorsPerTrack * 512 bytes/sector in struct DosEnvec (=pb_Environment[]) in struct PartitionBlock.

		That's from the physical drive part, the actual disk size limit for the partitions may be much smaller depending on the partitioning software, if it's only using the logical sizes instead, which is likely the case, it's only 8 ZiB with 512 bytes/sector: 32 bit rdb_HiCylinder * 32 bit rdb_CylBlocks * 512 bytes/sector = 2^73 bytes. For using the logical sizes using simple uint64 calculations
		(with some overflow checks) should be enough, for more a math library with support for larger integers needs to be used which probably no partitioning software does.

		But note: Nothing in struct RigiDiskBlock is used by the file systems for mounting the partitions, they only get the information from the struct PartitionBlock blocks, it's only a problem for the partitioning software creating the partitions correctly - as soon as there are HDs larger than 8 ZB while still using 512 bytes/sector if that ever happens.

Martin Steigerwald: Blanked the page

2012-06-18T20:05:58Z

Blanked the page

← Older revision		Revision as of 20:05, 18 June 2012
Line 1:		Line 1:
	== Introduction ==
	The Rigid Disk Block (RDB) is the Amiga way to store information about mass storage geometries and partitioning. Compared to the old, but still widely in used PC standard Master Boot Record (MBR) its a flexible structure with a linked list for the partitions.

	It is also able to store complete filesystem binaries and boot code, tough this is not used on AmigaOS 4 anymore.

	=== Limits ===
	It can store as much partitions as can fit in the reserved area for the RDB. There is no distinction between primary and logical partitions like in the Master Boot Record (MBR) standard for the PC platform.

	==== Disk size ====
	The RDB has a quite high limit on the maximum device size, but note that currently each filesystem interprets the partition layout by itself.

	The raw 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

	It's even much more if the sector size (rdb_BlockBytes and de_SizeBlock) is larger than 512 bytes, but AmigaOS 4.1 doesn't support anything but 512 bytes/sector HDs yet.

	==== Partition size ====
	For the partitions the maximum size is:

	32 bit (de_HighCyl + 1 - de_LowCyl) (to get the partition size) * 32 bit de_Surfaces * 32 bit de_SectorsPerTrack * 512 bytes/sector in struct DosEnvec (=pb_Environment[]) in struct PartitionBlock.

	That's from the physical drive part, the actual disk size limit for the partitions may be much smaller depending on the partitioning software, if it's only using the logical sizes instead, which is likely the case, it's only 8 ZiB with 512 bytes/sector: 32 bit rdb_HiCylinder * 32 bit rdb_CylBlocks * 512 bytes/sector = 2^73 bytes. For using the logical sizes using simple uint64 calculations
	(with some overflow checks) should be enough, for more a math library with support for larger integers needs to be used which probably no partitioning software does.

	But note: Nothing in struct RigiDiskBlock is used by the file systems for mounting the partitions, they only get the information from the struct PartitionBlock blocks, it's only a problem for the partitioning software creating the partitions correctly - as soon as there are HDs larger than 8 ZB while still using 512 bytes/sector if that ever happens.