en/handbook/hb-install-hppa-disk.xml

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<!DOCTYPE sections SYSTEM "/dtd/book.dtd">

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<sections>
<section>
<title>Introduction to Block Devices</title>
<subsection>
<title>Block Devices</title>
<body>

<p>
We'll take a good look at disk-oriented aspects of Gentoo Linux
and Linux in general, including Linux filesystems, partitions and block devices.
Then, once you're familiar with the ins and outs of disks and filesystems,
you'll be guided through the process of setting up partitions and filesystems
for your Gentoo Linux installation.
</p>

<p>
To begin, we'll introduce <e>block devices</e>. The most famous block device is
probably the one that represents the first SCSI HD in a Linux system, namely
<path>/dev/sda</path>.
</p>

<p>
The block devices above represent an abstract interface to the disk. User
programs can use these block devices to interact with your disk without worrying
about whether your drives are IDE, SCSI or something else. The program can
simply address the storage on the disk as a bunch of contiguous,
randomly-accessible 512-byte blocks.
</p>

</body>
</subsection>
<subsection>
<title>Partitions and Slices</title>
<body>

<p>
Although it is theoretically possible to use a full disk to house your Linux
system, this is almost never done in practice. Instead, full disk block devices
are split up in smaller, more manageable block devices. On most systems,
these are called <e>partitions</e>. Other architectures use a similar technique,
called <e>slices</e>.
</p>

</body>
</subsection>
</section>
<section>
<title>Designing a Partitioning Scheme</title>
<subsection>
<title>How Many and How Big?</title>
<body>

<p>
The number of partitions is highly dependent on your environment. For instance,
if you have lots of users, you will most likely want to have your
<path>/home</path> separate as it increases security and makes backups easier.
If you are installing Gentoo to perform as a mailserver, your 
<path>/var</path> should be separate as all mails are stored inside 
<path>/var</path>. A good choice of filesystem will then maximise your 
performance. Gameservers will have a separate <path>/opt</path> as most gaming 
servers are installed there. The reason is similar for <path>/home</path>: 
security and backups.
</p>

<p>
As you can see, it very much depends on what you want to achieve. Separate
partitions or volumes have the following advantages:
</p>

<ul>
<li>
  You can choose the best performing filesystem for each partition or volume
</li>
<li>
  Your entire system cannot run out of free space if one defunct tool is
  continuously writing files to a partition or volume
</li>
<li>
  If necessary, file system checks are reduced in time, as multiple checks can
  be done in parallel (although this advantage is more with multiple disks than
  it is with multiple partitions)
</li>
<li>
  Security can be enhanced by mounting some partitions or volumes read-only, 
  nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
</li>
</ul>

<p>
However, multiple partitions have one big disadvantage: if not configured 
properly, you might result in having a system with lots
of free space on one partition and none on another. There is also a 15-partition
limit for SCSI and SATA.
</p>

</body>
</subsection>
</section>
<section>
<title>Using fdisk on HPPA to Partition your Disk</title>
<body>

<p>
Use <c>fdisk</c> to create the partitions you want:
</p>

<pre caption="Partitioning the disk">
# <i>fdisk /dev/sda</i>
</pre>

<p>
HPPA machines use the PC standard DOS partition tables.  To create a new 
DOS partition table, simply use the <c>o</c> command.
</p>

<pre caption="Creating a DOS partition table">
# <i>fdisk /dev/sda</i>

Command (m for help): <i>o</i>
Building a new DOS disklabel.
</pre>

<p>
PALO (the HPPA bootloader) needs a special partition to work.  You have 
to create a partition of at least 16Mb at the beginning of your disk.  
The partition type must be of type <e>f0</e> (Linux/PA-RISC boot).
</p>

<impo>
If you ignore this and continue without a special PALO partition, your system
will stop loving you and fail to start. Also, if your disk is larger than 2Gb,
make sure that the boot partition is in the first 2Gb of your disk. PALO is
unable to read a kernel after the 2Gb limit.
</impo>

<pre caption="A simple default partition schema">
# <i>cat /etc/fstab</i>
/dev/sda2    /boot   ext3    noauto,noatime   1 1
/dev/sda3    none    swap    sw               0 0
/dev/sda4    /       ext3    noatime          0 0

# <i>fdisk /dev/sda</i>

Command (m for help): <i>p</i>

Disk /dev/sda: 4294 MB, 4294816768 bytes
133 heads, 62 sectors/track, 1017 cylinders
Units = cylinders of 8246 * 512 = 4221952 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1           8       32953   f0  Linux/PA-RISC boot
/dev/sda2               9          20       49476   83  Linux
/dev/sda3              21          70      206150   82  Linux swap
/dev/sda4              71        1017     3904481   83  Linux
</pre>

<p>
Now that your partitions are created, you can now continue with <uri
link="#filesystems">Creating Filesystems</uri>.
</p>

</body>
</section>
<section id="filesystems">
<title>Creating Filesystems</title>
<subsection>
<title>Introduction</title>
<body>

<p>
Now that your partitions are created, it is time to place a filesystem on them. 
If you don't care about what filesystem to choose and are happy with what we use
as default in this handbook, continue with <uri 
link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
Otherwise read on to learn about the available filesystems...
</p>

</body>
</subsection>
<subsection>
<title>Filesystems?</title>
<body>

<p>
Several filesystems are available. Ext2, ext3, XFS and reiserfs are found stable on 
the HPPA architecture. The others are very experimental.
</p>

<p>
<b>ext2</b> is the tried and true Linux filesystem but doesn't have metadata
journaling, which means that routine ext2 filesystem checks at startup time can
be quite time-consuming. There is now quite a selection of newer-generation
journaled filesystems that can be checked for consistency very quickly and are
thus generally preferred over their non-journaled counterparts. Journaled
filesystems prevent long delays when you boot your system and your filesystem
happens to be in an inconsistent state.
</p>

<p>
<b>ext3</b> is the journaled version of the ext2 filesystem, providing metadata
journaling for fast recovery in addition to other enhanced journaling modes like
full data and ordered data journaling. ext3 is a very good and reliable
filesystem. It has an additional hashed b-tree indexing option that enables 
high performance in almost all situations. In short, ext3 is an excellent 
filesystem.
</p>

<p>
<b>ReiserFS</b> is a B*-tree based filesystem that has very good overall 
performance and greatly outperforms both ext2 and ext3 when dealing with small 
files (files less than 4k), often by a factor of 10x-15x. ReiserFS also scales 
extremely well and has metadata journaling. As of kernel 2.4.18+, ReiserFS is 
solid and usable as both general-purpose filesystem and for extreme cases such 
as the creation of large filesystems, the use of many small files, very large 
files and directories containing tens of thousands of files. 
</p>

<p>
<b>XFS</b> is a filesystem with metadata journaling which comes with a robust
feature-set and is optimized for scalability. We only recommend using this
filesystem on Linux systems with high-end SCSI and/or fibre channel storage and
an uninterruptible power supply. Because XFS aggressively caches in-transit data
in RAM, improperly designed programs (those that don't take proper precautions
when writing files to disk and there are quite a few of them) can lose a good
deal of data if the system goes down unexpectedly.
</p>

<p>
<b>JFS</b> is IBM's high-performance journaling filesystem. It has recently 
become production-ready and there hasn't been a sufficient track record to 
comment positively nor negatively on its general stability at this point.
</p>

</body>
</subsection>
<subsection id="filesystems-apply">
<title>Applying a Filesystem to a Partition</title>
<body>

<p>
To create a filesystem on a partition or volume, there are tools available for 
each possible filesystem:
</p>

<table>
<tr>
  <th>Filesystem</th>
  <th>Creation Command</th>
</tr>
<tr>
  <ti>ext2</ti>
  <ti><c>mke2fs</c></ti>
</tr>
<tr>
  <ti>ext3</ti>
  <ti><c>mke2fs -j</c></ti>
</tr>
<tr>
  <ti>reiserfs</ti>
  <ti><c>mkreiserfs</c></ti>
</tr>
<tr>
  <ti>xfs</ti>
  <ti><c>mkfs.xfs</c></ti>
</tr>
<tr>
  <ti>jfs</ti>
  <ti><c>mkfs.jfs</c></ti>
</tr>
</table>

<p>
For instance, to have the boot partition (<path>/dev/sda2</path> in our
example) in ext2 and the root partition (<path>/dev/sda4</path> in our example)
in ext3 (as in our example), you would use:
</p>

<pre caption="Applying a filesystem on a partition">
# <i>mke2fs /dev/sda2</i>
# <i>mke2fs -j /dev/sda4</i>
</pre>

<p>
Now create the filesystems on your newly created partitions (or logical
volumes).
</p>

</body>
</subsection>
<subsection>
<title>Activating the Swap Partition</title>
<body>

<p>
<c>mkswap</c> is the command that is used to initialize swap partitions:
</p>

<pre caption="Creating a Swap signature">
# <i>mkswap /dev/sda3</i>
</pre>

<p>
To activate the swap partition, use <c>swapon</c>:
</p>

<pre caption="Activating the swap partition">
# <i>swapon /dev/sda3</i>
</pre>

<p>
Create and activate the swap now.
</p>

</body>
</subsection>
</section>
<section>
<title>Mounting</title>
<body>

<p>
Now that your partitions are initialized and are housing a filesystem, it is
time to mount those partitions. Use the <c>mount</c> command. Don't forget to
create the necessary mount directories for every partition you created. As an
example we mount the root and boot partition:
</p>

<pre caption="Mounting partitions">
# <i>mount /dev/sda4 /mnt/gentoo</i>
# <i>mkdir /mnt/gentoo/boot</i>
# <i>mount /dev/sda2 /mnt/gentoo/boot</i>
</pre>

<note>
If you want your <path>/tmp</path> to reside on a separate partition, be sure to
change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>. This
also holds for <path>/var/tmp</path>.
</note>

<p>
We will also have to mount the proc filesystem (a virtual interface with the 
kernel) on <path>/proc</path>. But first we will need to place our files on the partitions.
</p>

<p>
Continue with <uri link="?part=1&amp;chap=5">Installing the Gentoo
Installation Files</uri>.
</p>

</body>
</section>
</sections>
1	<?xml version='1.0' encoding='UTF-8'?>
2	<!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3
4	<!-- The content of this document is licensed under the CC-BY-SA license -->
5	<!-- See http://creativecommons.org/licenses/by-sa/1.0 -->
6
7	<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-hppa-disk.xml,v 1.8 2004/09/14 11:55:12 swift Exp $ -->
8
9	<sections>
10	<section>
11	<title>Introduction to Block Devices</title>
12	<subsection>
13	<title>Block Devices</title>
14	<body>
15
16	<p>
17	We'll take a good look at disk-oriented aspects of Gentoo Linux
18	and Linux in general, including Linux filesystems, partitions and block devices.
19	Then, once you're familiar with the ins and outs of disks and filesystems,
20	you'll be guided through the process of setting up partitions and filesystems
21	for your Gentoo Linux installation.
22	</p>
23
24	<p>
25	To begin, we'll introduce <e>block devices</e>. The most famous block device is
26	probably the one that represents the first SCSI HD in a Linux system, namely
27	<path>/dev/sda</path>.
28	</p>
29
30	<p>
31	The block devices above represent an abstract interface to the disk. User
32	programs can use these block devices to interact with your disk without worrying
33	about whether your drives are IDE, SCSI or something else. The program can
34	simply address the storage on the disk as a bunch of contiguous,
35	randomly-accessible 512-byte blocks.
36	</p>
37
38	</body>
39	</subsection>
40	<subsection>
41	<title>Partitions and Slices</title>
42	<body>
43
44	<p>
45	Although it is theoretically possible to use a full disk to house your Linux
46	system, this is almost never done in practice. Instead, full disk block devices
47	are split up in smaller, more manageable block devices. On most systems,
48	these are called <e>partitions</e>. Other architectures use a similar technique,
49	called <e>slices</e>.
50	</p>
51
52	</body>
53	</subsection>
54	</section>
55	<section>
56	<title>Designing a Partitioning Scheme</title>
57	<subsection>
58	<title>How Many and How Big?</title>
59	<body>
60
61	<p>
62	The number of partitions is highly dependent on your environment. For instance,
63	if you have lots of users, you will most likely want to have your
64	<path>/home</path> separate as it increases security and makes backups easier.
65	If you are installing Gentoo to perform as a mailserver, your
66	<path>/var</path> should be separate as all mails are stored inside
67	<path>/var</path>. A good choice of filesystem will then maximise your
68	performance. Gameservers will have a separate <path>/opt</path> as most gaming
69	servers are installed there. The reason is similar for <path>/home</path>:
70	security and backups.
71	</p>
72
73	<p>
74	As you can see, it very much depends on what you want to achieve. Separate
75	partitions or volumes have the following advantages:
76	</p>
77
78	<ul>
79	<li>
80	You can choose the best performing filesystem for each partition or volume
81	</li>
82	<li>
83	Your entire system cannot run out of free space if one defunct tool is
84	continuously writing files to a partition or volume
85	</li>
86	<li>
87	If necessary, file system checks are reduced in time, as multiple checks can
88	be done in parallel (although this advantage is more with multiple disks than
89	it is with multiple partitions)
90	</li>
91	<li>
92	Security can be enhanced by mounting some partitions or volumes read-only,
93	nosuid (setuid bits are ignored), noexec (executable bits are ignored) etc.
94	</li>
95	</ul>
96
97	<p>
98	However, multiple partitions have one big disadvantage: if not configured
99	properly, you might result in having a system with lots
100	of free space on one partition and none on another. There is also a 15-partition
101	limit for SCSI and SATA.
102	</p>
103
104	</body>
105	</subsection>
106	</section>
107	<section>
108	<title>Using fdisk on HPPA to Partition your Disk</title>
109	<body>
110
111	<p>
112	Use <c>fdisk</c> to create the partitions you want:
113	</p>
114
115	<pre caption="Partitioning the disk">
116	# <i>fdisk /dev/sda</i>
117	</pre>
118
119	<p>
120	HPPA machines use the PC standard DOS partition tables. To create a new
121	DOS partition table, simply use the <c>o</c> command.
122	</p>
123
124	<pre caption="Creating a DOS partition table">
125	# <i>fdisk /dev/sda</i>
126
127	Command (m for help): <i>o</i>
128	Building a new DOS disklabel.
129	</pre>
130
131	<p>
132	PALO (the HPPA bootloader) needs a special partition to work. You have
133	to create a partition of at least 16Mb at the beginning of your disk.
134	The partition type must be of type <e>f0</e> (Linux/PA-RISC boot).
135	</p>
136
137	<impo>
138	If you ignore this and continue without a special PALO partition, your system
139	will stop loving you and fail to start. Also, if your disk is larger than 2Gb,
140	make sure that the boot partition is in the first 2Gb of your disk. PALO is
141	unable to read a kernel after the 2Gb limit.
142	</impo>
143
144	<pre caption="A simple default partition schema">
145	# <i>cat /etc/fstab</i>
146	/dev/sda2 /boot ext3 noauto,noatime 1 1
147	/dev/sda3 none swap sw 0 0
148	/dev/sda4 / ext3 noatime 0 0
149
150	# <i>fdisk /dev/sda</i>
151
152	Command (m for help): <i>p</i>
153
154	Disk /dev/sda: 4294 MB, 4294816768 bytes
155	133 heads, 62 sectors/track, 1017 cylinders
156	Units = cylinders of 8246 * 512 = 4221952 bytes
157
158	Device Boot Start End Blocks Id System
159	/dev/sda1 1 8 32953 f0 Linux/PA-RISC boot
160	/dev/sda2 9 20 49476 83 Linux
161	/dev/sda3 21 70 206150 82 Linux swap
162	/dev/sda4 71 1017 3904481 83 Linux
163	</pre>
164
165	<p>
166	Now that your partitions are created, you can now continue with <uri
167	link="#filesystems">Creating Filesystems</uri>.
168	</p>
169
170	</body>
171	</section>
172	<section id="filesystems">
173	<title>Creating Filesystems</title>
174	<subsection>
175	<title>Introduction</title>
176	<body>
177
178	<p>
179	Now that your partitions are created, it is time to place a filesystem on them.
180	If you don't care about what filesystem to choose and are happy with what we use
181	as default in this handbook, continue with <uri
182	link="#filesystems-apply">Applying a Filesystem to a Partition</uri>.
183	Otherwise read on to learn about the available filesystems...
184	</p>
185
186	</body>
187	</subsection>
188	<subsection>
189	<title>Filesystems?</title>
190	<body>
191
192	<p>
193	Several filesystems are available. Ext2, ext3, XFS and reiserfs are found stable on
194	the HPPA architecture. The others are very experimental.
195	</p>
196
197	<p>
198	<b>ext2</b> is the tried and true Linux filesystem but doesn't have metadata
199	journaling, which means that routine ext2 filesystem checks at startup time can
200	be quite time-consuming. There is now quite a selection of newer-generation
201	journaled filesystems that can be checked for consistency very quickly and are
202	thus generally preferred over their non-journaled counterparts. Journaled
203	filesystems prevent long delays when you boot your system and your filesystem
204	happens to be in an inconsistent state.
205	</p>
206
207	<p>
208	<b>ext3</b> is the journaled version of the ext2 filesystem, providing metadata
209	journaling for fast recovery in addition to other enhanced journaling modes like
210	full data and ordered data journaling. ext3 is a very good and reliable
211	filesystem. It has an additional hashed b-tree indexing option that enables
212	high performance in almost all situations. In short, ext3 is an excellent
213	filesystem.
214	</p>
215
216	<p>
217	<b>ReiserFS</b> is a B*-tree based filesystem that has very good overall
218	performance and greatly outperforms both ext2 and ext3 when dealing with small
219	files (files less than 4k), often by a factor of 10x-15x. ReiserFS also scales
220	extremely well and has metadata journaling. As of kernel 2.4.18+, ReiserFS is
221	solid and usable as both general-purpose filesystem and for extreme cases such
222	as the creation of large filesystems, the use of many small files, very large
223	files and directories containing tens of thousands of files.
224	</p>
225
226	<p>
227	<b>XFS</b> is a filesystem with metadata journaling which comes with a robust
228	feature-set and is optimized for scalability. We only recommend using this
229	filesystem on Linux systems with high-end SCSI and/or fibre channel storage and
230	an uninterruptible power supply. Because XFS aggressively caches in-transit data
231	in RAM, improperly designed programs (those that don't take proper precautions
232	when writing files to disk and there are quite a few of them) can lose a good
233	deal of data if the system goes down unexpectedly.
234	</p>
235
236	<p>
237	<b>JFS</b> is IBM's high-performance journaling filesystem. It has recently
238	become production-ready and there hasn't been a sufficient track record to
239	comment positively nor negatively on its general stability at this point.
240	</p>
241
242	</body>
243	</subsection>
244	<subsection id="filesystems-apply">
245	<title>Applying a Filesystem to a Partition</title>
246	<body>
247
248	<p>
249	To create a filesystem on a partition or volume, there are tools available for
250	each possible filesystem:
251	</p>
252
253	<table>
254	<tr>
255	<th>Filesystem</th>
256	<th>Creation Command</th>
257	</tr>
258	<tr>
259	<ti>ext2</ti>
260	<ti><c>mke2fs</c></ti>
261	</tr>
262	<tr>
263	<ti>ext3</ti>
264	<ti><c>mke2fs -j</c></ti>
265	</tr>
266	<tr>
267	<ti>reiserfs</ti>
268	<ti><c>mkreiserfs</c></ti>
269	</tr>
270	<tr>
271	<ti>xfs</ti>
272	<ti><c>mkfs.xfs</c></ti>
273	</tr>
274	<tr>
275	<ti>jfs</ti>
276	<ti><c>mkfs.jfs</c></ti>
277	</tr>
278	</table>
279
280	<p>
281	For instance, to have the boot partition (<path>/dev/sda2</path> in our
282	example) in ext2 and the root partition (<path>/dev/sda4</path> in our example)
283	in ext3 (as in our example), you would use:
284	</p>
285
286	<pre caption="Applying a filesystem on a partition">
287	# <i>mke2fs /dev/sda2</i>
288	# <i>mke2fs -j /dev/sda4</i>
289	</pre>
290
291	<p>
292	Now create the filesystems on your newly created partitions (or logical
293	volumes).
294	</p>
295
296	</body>
297	</subsection>
298	<subsection>
299	<title>Activating the Swap Partition</title>
300	<body>
301
302	<p>
303	<c>mkswap</c> is the command that is used to initialize swap partitions:
304	</p>
305
306	<pre caption="Creating a Swap signature">
307	# <i>mkswap /dev/sda3</i>
308	</pre>
309
310	<p>
311	To activate the swap partition, use <c>swapon</c>:
312	</p>
313
314	<pre caption="Activating the swap partition">
315	# <i>swapon /dev/sda3</i>
316	</pre>
317
318	<p>
319	Create and activate the swap now.
320	</p>
321
322	</body>
323	</subsection>
324	</section>
325	<section>
326	<title>Mounting</title>
327	<body>
328
329	<p>
330	Now that your partitions are initialized and are housing a filesystem, it is
331	time to mount those partitions. Use the <c>mount</c> command. Don't forget to
332	create the necessary mount directories for every partition you created. As an
333	example we mount the root and boot partition:
334	</p>
335
336	<pre caption="Mounting partitions">
337	# <i>mount /dev/sda4 /mnt/gentoo</i>
338	# <i>mkdir /mnt/gentoo/boot</i>
339	# <i>mount /dev/sda2 /mnt/gentoo/boot</i>
340	</pre>
341
342	<note>
343	If you want your <path>/tmp</path> to reside on a separate partition, be sure to
344	change its permissions after mounting: <c>chmod 1777 /mnt/gentoo/tmp</c>. This
345	also holds for <path>/var/tmp</path>.
346	</note>
347
348	<p>
349	We will also have to mount the proc filesystem (a virtual interface with the
350	kernel) on <path>/proc</path>. But first we will need to place our files on the partitions.
351	</p>
352
353	<p>
354	Continue with <uri link="?part=1&chap=5">Installing the Gentoo
355	Installation Files</uri>.
356	</p>
357
358	</body>
359	</section>
360	</sections>