Mac HD Partitions - Revision history

AshleySueMas at 20:16, 21 February 2014

2014-02-21T20:16:06Z

Liliana at 18:10, 17 July 2013

2013-07-17T18:10:34Z

Mikem at 18:24, 21 June 2012

2012-06-21T18:24:59Z

Tonyr: /* Manual Partitioning */ add fdisk script link

2007-02-14T22:25:24Z

Manual Partitioning: add fdisk script link

Tonyr: /* The Partitions */ add partition math comments

2007-02-14T19:20:56Z

The Partitions: add partition math comments

Tonyr: /* The Partitions */

2007-02-14T19:09:01Z

The Partitions

Tonyr: final comments in the Manual Partitioning section

2007-02-13T05:15:37Z

final comments in the Manual Partitioning section

Tonyr at 03:16, 13 February 2007

2007-02-13T03:16:58Z

Tonyr: /* Manual Partitioning */ more writing

2007-02-13T02:28:29Z

Manual Partitioning: more writing

Tonyr: /* Manual Partitioning */ part of manual partitioning example

2007-02-13T01:00:38Z

Manual Partitioning: part of manual partitioning example

← Older revision		Revision as of 20:16, 21 February 2014
Line 76:		Line 76:
	There is a [[Mac Build Scripts#Generate fdisk script\|script]] that automates the generation of these commands for a particular device.		There is a [[Mac Build Scripts#Generate fdisk script\|script]] that automates the generation of these commands for a particular device.

−		+	[[Category:Macintosh Archive]]
−
−	~~[[Category:Delete]]~~
−	[[Category:Macintosh]]

← Older revision		Revision as of 18:10, 17 July 2013
Line 79:		Line 79:

	[[Category:Delete]]		[[Category:Delete]]
		+	[[Category:Macintosh]]

← Older revision		Revision as of 18:24, 21 June 2012
Line 78:		Line 78:


−	[[Category:~~Macintosh~~]]	+	[[Category:Delete]]

@@ Line 73: / Line 73: @@
 The fourth (swap) partition is also created with the '''c''' command, but with a lot less work. The start block is the calculated simply by adding the start block and length of the third partition, and the length of the swap partition is 750000 as we calculated before.  The name of this partition apparently '''is''' important.  The name '''swap''' seems to be recognized by '''fdisk''' as significant, as seen in the final output of the '''p'''command.
   <text of swap c command dialog and p command here>
 [[Category:Macintosh]]

@@ Line 23: / Line 23: @@
 * The third partition, '''/dev/hda3''', is the Linux partition.  It starts at block 2018, the first block after the end of the second partition.  It's length is almost the entire rest of the disk, except for  the space reserved for the swap partition.  The Ubuntu installation partitioning process installs an '''ext3''' filesystem here by default.
 * The fourth partition, '''/dev/hda4''', is the swap partition.  It start immediately after the Linux partition, and it's length represents approximately 1.5 times memory size.
 During Ubuntu installation from CD, at the partition creation step, the size of the swap partition is calculated from the memory size, and the size of the Linux partition is caclulated as whatever is left over.
-This information will be used later in this article when talking about [[#Manual Partitioning|Manual Partitioning]].  Notice that the '''base''', or start, block of a partition can be calculated by adding the lengths of all previous partitions, and then adding one to that total.
+This information will be used later in this article when talking about [[#Manual Partitioning|Manual Partitioning]].  Notice that the '''base''', or start, block of a partition can be calculated by adding the lengths of all previous partitions, and then adding one to that total.  Another way to find the start block of the next partition is to add a partition's length and start block.
 ==Manual Partitioning==

@@ Line 14: / Line 14: @@
   DeviceType=0x0, DeviceId=0x0
-Note that this looks different from the x86 (PC) fdisk partition table, but the contents are essentially the same.  One major difference is that the PPC partition table listing actually contains a reference to the table itself.  Another difference is the partition type names. Let's examine the table a little closer.
+Note that this looks different from the x86 (PC) fdisk partition table, but the contents are essentially the same.  One major difference is that the PPC partition table listing actually contains a reference to the table itself.  Another difference is the partition type names. Let's examine the table a little more closely.
 * The table has several lines.  The first line shows the device being examined, in this case '''/dev/hda'''. The second line contains column titles.  The names are pretty much self explanatory; the '#' represents 'partition number'.

@@ Line 21: / Line 21: @@
 * The first partition, '''/dev/hda1''', contains the partition table (called '''partition map''' here).  It starts at block 1 and is 63 blocks long. It has no formal filesystem (i.e., it is raw data).
 * The second partition, /'''dev/hda2''', contains the boot information.  Its '''type''' and '''system''' designations indicate this.  This partition is created as an '''hfs''' filesystem.  ('''hfs''' is the original Apple filesystem type).  It contains three files: '''ofboot.b''', '''yaboot''', and '''yaboot.conf'''.  The partition can actually be mounted in Linux with type '''hfs''', and the files manipulated.  This partition starts at block 64, the first block after the end of the first partition, and is 1954 blocks long.
-* The third partition, '''/dev/hda3''', is the Linux partition.  It starts at block 2018, the fist block after the end of the second partition.  It's length is almost the entire rest of the disk, except for  the space reserved for the swap partition.  The Ubuntu installation partitioning process installs an '''ext3''' filesystem here by default.
+* The third partition, '''/dev/hda3''', is the Linux partition.  It starts at block 2018, the first block after the end of the second partition.  It's length is almost the entire rest of the disk, except for  the space reserved for the swap partition.  The Ubuntu installation partitioning process installs an '''ext3''' filesystem here by default.
 * The fourth partition, '''/dev/hda4''', is the swap partition.  It start immediately after the Linux partition, and it's length represents approximately 1.5 times memory size.
@@ Line 67: / Line 67: @@
 The third partition is created with the '''c''' command.  The dialog in this case prompts for start, length and name.  As before, the name is not important, and we use '''untitled'''.  The start block is 2018, which
-is the sum of the lengths of the previous partitions plus 1 (63 + 1954 +1).  The size will take a little work to come up with.  The trick here is to figure out  how big the swap (fourth) partition should be, and subtract that from the unused space.  It was pointed out earlier that any unused space shows up as the last line in the partition table. Let's use the example partition table in [[#The Partitions|The Partitions]]. The partition table liste above shows that the remaining space is
+is the sum of the lengths of the previous partitions plus 1 (63 + 1954 +1).  The size will take a little work to come up with.  The trick here is to figure out  how big the swap (fourth) partition should be, and subtract that from the unused space.  It was pointed out earlier that any unused space shows up as the last line in the partition table. Let's use the example partition table in [[#The Partitions|The Partitions]]. The partition table liste above shows that the remaining space is 14666272 blocks.  If we assume that the target system (the one this drive will go into) has 256 MB of memory, then we can estimate that the swap space required is 384MB, or 750000 blocks. (The actual calculation used by Ubuntu is not this simple, and the result is a little different).  We can now calculate the Linux partition length as (14666272 - 750000), or 13916272 blocks.
 [[Category:Macintosh]]

@@ Line 34: / Line 34: @@
   /dev/hda
   Command (? for help):
-Typing ''?''' at this point will produce a list of possible commands:
+Typing '''?''' at this point will produce a list of possible commands:
   Command (? for help): ?
   Commands are:
@@ Line 57: / Line 57: @@
 # that the source drive, '''/dev/hdc''', was installed normally from an alternate install CD.
 When '''fdisk /dev/hdd''' is run from the command line, the fdisk command prompt appears as usual. At this point entering the command '''p''' results in a message that no partition map is defined:
-  <test of p command response here>
+  <text of p command response here>
-The '''i''' command will create an empty partition map.  A '''p''' command at this point will show an empty partition map.
+The '''i''' command will create an empty partition map.  A '''p''' command at this point will show a partition map with one entry, the partition map itself, beginning at block 1 with length 63.
   <text of partion map creation and empty partition map response here>
 We will create the rest of the partitions in the order that they will appear finally in the partition map.
 To create the boot, or second, partition, (remember that the partition map is actually the first partition), use the '''C''' (capital C) command.  A little explanation is required here.  There is a command '''b''' to explicitly create an 800k boot partition.  Such a partition is 1600 blocks long, but if you look back in [[#The Partitions|The Partitions]], you will see that see that we need a partition that is 1954 blocks long.  The '''C''' command gives us more control to do that, but we pay the price of having to specify more of the creation information.
 [[Category:Macintosh]]

@@ Line 30: / Line 30: @@
 The Ubuntu installation partitioning process can be duplicated manually.  Such an approach is useful, for example, in replicating Ubuntu PowerPC Linux disks for savingtime during Mac Rebuild.
-A common utility program for creating partitions, and the oe that will be used here, is '''fdisk'''.  Again, its behavior. appearance and functionality are not exactly the same as its PC counterpart.  It is invoked on a terminal command line with a single argument: the name of the device to be partitioned.  The first response is a repetition of the deivce name, and a command inout request:
+A common utility program for creating partitions, and the one that will be used in examples here, is '''fdisk'''.  Again, its behavior. appearance and functionality are not exactly the same as its PC counterpart.  It is invoked on a terminal command line with a single argument: the name of the device to be partitioned.  The first response is a repetition of the deivce name, and a command inout request:
   $ fdisk /dev/hda
   /dev/hda
@@ Line 50: / Line 50: @@
     q    quit editing (don't save changes)
-When creating partitions, is is always a good idea to use the '''p''' command frequently to check you work.  No changes are actually written to the disk until you usethe '''w'''command, but it is a good idea to check yourself anywa as you go along.  As always, there is a '''man''' page for '''fdisk''' that gives more information.
+When creating partitions, is is always a good idea to use the '''p''' command frequently to check you work.  No changes are actually written to the disk until you use the '''w'''command, but it is a good idea to check yourself anywa as you go along.  As always, there is a '''man''' page for '''fdisk''' that gives more information.
 [[Category:Macintosh]]