| 1 |
neysx 05/08/18 12:59:17 |
| 2 |
|
| 3 |
Added: xml/htdocs/doc/en/articles maximum-swappage.xml |
| 4 |
partition-planning-tips.xml partitioning-p1.xml |
| 5 |
partitioning-p2.xml |
| 6 |
Log: |
| 7 |
New GuideXMLified articles from #100709, #102652 & #102666 |
| 8 |
|
| 9 |
Revision Changes Path |
| 10 |
1.1 xml/htdocs/doc/en/articles/maximum-swappage.xml |
| 11 |
|
| 12 |
file : http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/maximum-swappage.xml?rev=1.1&content-type=text/x-cvsweb-markup&cvsroot=gentoo |
| 13 |
plain: http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/maximum-swappage.xml?rev=1.1&content-type=text/plain&cvsroot=gentoo |
| 14 |
|
| 15 |
Index: maximum-swappage.xml |
| 16 |
=================================================================== |
| 17 |
<?xml version="1.0" encoding="UTF-8"?> |
| 18 |
<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
| 19 |
<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/articles/maximum-swappage.xml,v 1.1 2005/08/18 12:59:17 neysx Exp $ --> |
| 20 |
|
| 21 |
<guide link="/doc/en/articles/maximum-swappage.xml" lang="en"> |
| 22 |
<title>Maximum swappage</title> |
| 23 |
|
| 24 |
<author title="Author"> |
| 25 |
<mail link="drobbins@g.o">Daniel Robbins</mail> |
| 26 |
</author> |
| 27 |
<author title="Editor"> |
| 28 |
<mail link="jackdark@×××××.com">Joshua Saddler</mail> |
| 29 |
</author> |
| 30 |
|
| 31 |
<abstract> |
| 32 |
Learn how to improve the swap performance on your Linux server by several |
| 33 |
orders of magnitude. Author Daniel Robbins takes you through this quick tip on |
| 34 |
getting the most from your server. |
| 35 |
</abstract> |
| 36 |
|
| 37 |
<!-- The original version of this article was first published on IBM |
| 38 |
developerWorks, and is property of Westtech Information Services. This |
| 39 |
document is an updated version of the original article, and contains |
| 40 |
various improvements made by the Gentoo Linux Documentation team --> |
| 41 |
|
| 42 |
<version>1.0</version> |
| 43 |
<date>2005-08-15</date> |
| 44 |
|
| 45 |
<chapter> |
| 46 |
<title>Getting the most out of swap</title> |
| 47 |
<section> |
| 48 |
<body> |
| 49 |
|
| 50 |
<note> |
| 51 |
The original version of this article was first published on IBM developerWorks, |
| 52 |
and is property of Westtech Information Services. This document is an updated |
| 53 |
version of the original article, and contains various improvements made by the |
| 54 |
Gentoo Linux Documentation team. |
| 55 |
</note> |
| 56 |
|
| 57 |
<p> |
| 58 |
When you set up a brand new Linux server, do you create a single 128 MB swap |
| 59 |
partition? If so, did you know that you are severely limiting swap performance? |
| 60 |
Would you like to increase swap performance by several orders of magnitude, and |
| 61 |
to create swap partitions larger than 1 GB? It's possible, requiring no kernel |
| 62 |
patches or special hardware, just pure geek know-how! |
| 63 |
</p> |
| 64 |
|
| 65 |
<p> |
| 66 |
Some of you may not really care about swap. After all, Linux systems are |
| 67 |
typically very memory efficient, and swap is often barely touched. While often |
| 68 |
true on desktop systems, servers are another story. Because servers may handle |
| 69 |
unexpected stresses, such as runaway processes, denial of service attacks, or |
| 70 |
even the Slashdot effect, they need to have adequate high-speed swap so that |
| 71 |
they do not grind to a halt and possibly crash when all physical memory (and |
| 72 |
then some) is exhausted. |
| 73 |
</p> |
| 74 |
|
| 75 |
<p> |
| 76 |
Still not convinced that this is a big deal? I'll show you how easy it is to |
| 77 |
bring down a server by launching a massive amount of new processes. |
| 78 |
</p> |
| 79 |
|
| 80 |
<warn> |
| 81 |
Please, if you try this, do it only on a non-production server that you |
| 82 |
actually administer! |
| 83 |
</warn> |
| 84 |
|
| 85 |
<p> |
| 86 |
Let's say you have two customized <c>grep</c> commands in |
| 87 |
<path>/usr/bin</path>, called <c>bobgrep</c> and <c>jimgrep</c>. Now, let's |
| 88 |
assume that <c>bobgrep</c> is simply a shell script that calls the ELF |
| 89 |
executable <c>jimgrep</c>, as follows: |
| 90 |
</p> |
| 91 |
|
| 92 |
<pre caption="The bobgrep script"> |
| 93 |
#!/bin/bash |
| 94 |
jimgrep -r $* |
| 95 |
</pre> |
| 96 |
|
| 97 |
<p> |
| 98 |
Everything looks good so far, but what happens if <c>jimgre</c>p gets |
| 99 |
accidentally replaced with a symbolic link to <c>bobgrep?</c> Well, in that |
| 100 |
case, calling <c>bobgrep</c> or <c>jimgrep</c> will cause an infinite loop, |
| 101 |
causing hundreds of bash processes to be spawned in mere seconds. This actually |
| 102 |
happened to me once, and believe me, it hurt! |
| 103 |
</p> |
| 104 |
|
| 105 |
<p> |
| 106 |
If a server doesn't have adequate swap, a situation like this can cause the |
| 107 |
machine to lock up in much less than a minute. How do we fix the problem? One |
| 108 |
way is to increase the swap size beyond 128 MB. Fortunately for us, there is |
| 109 |
absolutely no 128 MB limit on swap under Linux 2.2.x+ and later kernels, as |
| 110 |
there was in the past. The current limits are approximately 2 GB on x86, |
| 111 |
PowerPC, and MC680x0 systems, 512 MB on MIPS systems, 128 GB on Alpha, and a |
| 112 |
whopping 3 terabytes on UltraSparc platforms! |
| 113 |
</p> |
| 114 |
|
| 115 |
<pre caption="Swap partition size limits under modern Linux kernels"> |
| 116 |
x86 2 Gigabytes |
| 117 |
PowerPC 2 Gigabytes |
| 118 |
Motorola 680x0 2 Gigabytes |
| 119 |
Sparc 1 Gigabyte |
| 120 |
MIPS 512 Megabytes |
| 121 |
Alpha 128 Gigabytes |
| 122 |
UltraSparc 3 Terabytes |
| 123 |
</pre> |
| 124 |
|
| 125 |
<p> |
| 126 |
While it's nice to be able to increase swap partition size to beyond 128 MB, |
| 127 |
how about increasing performance? Ideally, it would be nice if we could set up |
| 128 |
swap partitions in a RAID 0 stripe, so that reads and writes are equally |
| 129 |
distributed between all partitions. If these partitions are on separate drives |
| 130 |
and/or controllers, this will multiply swap file performance, allowing your |
| 131 |
servers to handle temporary memory usage "spikes" without getting dramatically |
| 132 |
bogged down. |
| 133 |
</p> |
| 134 |
|
| 135 |
<p> |
| 136 |
Amazingly, all modern Linux kernels, by default (with no special kernel options |
| 137 |
or patches) allow you to parallelize swap, just like a RAID 0 stripe. By using |
| 138 |
the <c>pri</c> option in <path>/etc/fstab</path> to set multiple swap |
| 139 |
partitions to the same priority, we tell Linux to use them in parallel: |
| 140 |
</p> |
| 141 |
|
| 142 |
<pre caption="Set multiple swap partitions to the same priority"> |
| 143 |
/dev/sda2 none swap sw,pri=3 0 0 |
| 144 |
/dev/sdb2 none swap sw,pri=3 0 0 |
| 145 |
/dev/sdc2 none swap sw,pri=3 0 0 |
| 146 |
/dev/sdd2 none swap sw,pri=1 0 0 |
| 147 |
</pre> |
| 148 |
|
| 149 |
<p> |
| 150 |
In the above example, Linux will use swap partitions sda2, sdb2, and sdc2 in |
| 151 |
parallel. Since these partitions are on different drives, and possibly even |
| 152 |
different SCSI controllers, read and write throughput will nearly triple. The |
| 153 |
fourth swap partition, sdd2, will be used only after the first three partitions |
| 154 |
have been exhausted. |
| 155 |
</p> |
| 156 |
|
| 157 |
<p> |
| 158 |
The <c>pri</c> option is really easy to use. The priority must be a number |
| 159 |
between 0 and 32767, with 32767 being the highest priority. The swap partitions |
| 160 |
will be used from highest priority to lowest priority, meaning that a partition |
| 161 |
with a priority of x will only be used only if all partitions with a priority |
| 162 |
greater than x are already full. If several partitions have the same priority, |
| 163 |
Linux will automatically parallelize access between them. This allows you to |
| 164 |
not only parallelize swap, but also prioritize access so that the partitions on |
| 165 |
the fastest drives (or regions of the drives) are used first. So, you can set |
| 166 |
up an emergency swap partition on an old, slower drive that will be used only |
| 167 |
if all high-speed swap is exhausted first. |
| 168 |
</p> |
| 169 |
|
| 170 |
<p> |
| 171 |
Now it's time to put some of this swapping knowledge into action. To loosely |
| 172 |
quote Mr. Miyagi of Karate Kid fame: "Swap on, swap off, geek-san!" |
| 173 |
</p> |
| 174 |
|
| 175 |
</body> |
| 176 |
</section> |
| 177 |
<section> |
| 178 |
<title>Resources</title> |
| 179 |
<body> |
| 180 |
|
| 181 |
<ul> |
| 182 |
<li> |
| 183 |
In <uri link="/doc/en/articles/partitioning-p1.xml">Partitioning in action: |
| 184 |
Moving /home</uri>, I show you step-by-step how to move <path>/home</path> |
| 185 |
to a new partition. |
| 186 |
</li> |
| 187 |
<li> |
| 188 |
In <uri link="/doc/en/articles/partitioning-p2.xml">Partitioning in |
| 189 |
action</uri>, I show you step-by-step how to move <path>/var</path> and |
| 190 |
<path>/tmp</path> to a new partition. |
| 191 |
</li> |
| 192 |
<li> |
| 193 |
In my second tip, <uri |
| 194 |
link="/doc/en/articles/partition-planning-tips.xml"> |
| 195 |
"Partition planning tips"</uri>, I share several ways of effectively |
| 196 |
organizing your partition layout. |
| 197 |
</li> |
| 198 |
<li> |
| 199 |
The <uri link="http://www.redhat.com/mirrors/LDP/LDP/sag/index.html"> Linux |
| 200 |
system administrator's guide</uri> mirrored on Red Hat's home page. |
| 201 |
</li> |
| 202 |
<li> |
| 203 |
A good high-level <uri link="http://www.gwdg.de/gs-2.0/chapter2_6.html"> |
| 204 |
overview of Linux system administration</uri>. |
| 205 |
</li> |
| 206 |
<li> |
| 207 |
For more information on optimizing file system performance, take a look at |
| 208 |
Linas Vepstas' <uri link="http://www.tldp.org">Linux Software RAID |
| 209 |
HOWTO</uri>. Since the most recent software RAID code has been merged into |
| 210 |
the 2.3 series kernels, it is a viable option for further enhancing Linux |
| 211 |
disk performance. |
| 212 |
</li> |
| 213 |
</ul> |
| 214 |
|
| 215 |
</body> |
| 216 |
|
| 217 |
|
| 218 |
|
| 219 |
1.1 xml/htdocs/doc/en/articles/partition-planning-tips.xml |
| 220 |
|
| 221 |
file : http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/partition-planning-tips.xml?rev=1.1&content-type=text/x-cvsweb-markup&cvsroot=gentoo |
| 222 |
plain: http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/partition-planning-tips.xml?rev=1.1&content-type=text/plain&cvsroot=gentoo |
| 223 |
|
| 224 |
Index: partition-planning-tips.xml |
| 225 |
=================================================================== |
| 226 |
<?xml version="1.0" encoding="UTF-8"?> |
| 227 |
<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
| 228 |
<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/articles/partition-planning-tips.xml,v 1.1 2005/08/18 12:59:17 neysx Exp $ --> |
| 229 |
|
| 230 |
<guide link="/doc/en/articles/partition-planning-tips.xml" lang="en"> |
| 231 |
<title>Partition planning tips</title> |
| 232 |
|
| 233 |
<author title="Author"> |
| 234 |
<mail link="drobbins@g.o">Daniel Robbins</mail> |
| 235 |
</author> |
| 236 |
<author title="Editor"> |
| 237 |
<mail link="jackdark@×××××.com">Joshua Saddler</mail> |
| 238 |
</author> |
| 239 |
|
| 240 |
<abstract> |
| 241 |
Organizing your partitions correctly can be fun and rewarding. This collection |
| 242 |
of tips will help you to use those sectors wisely. |
| 243 |
</abstract> |
| 244 |
|
| 245 |
<!-- The original version of this article was first published on IBM |
| 246 |
developerWorks, and is property of Westtech Information Services. This |
| 247 |
document is an updated version of the original article, and contains |
| 248 |
various improvements made by the Gentoo Linux Documentation team --> |
| 249 |
|
| 250 |
<version>1.0</version> |
| 251 |
<date>2005-08-15</date> |
| 252 |
|
| 253 |
<chapter> |
| 254 |
<title>How to keep things organized on disk</title> |
| 255 |
<section> |
| 256 |
<body> |
| 257 |
|
| 258 |
<note> |
| 259 |
The original version of this article was first published on IBM developerWorks, |
| 260 |
and is property of Westtech Information Services. This document is an updated |
| 261 |
version of the original article, and contains various improvements made by the |
| 262 |
Gentoo Linux Documentation team. |
| 263 |
</note> |
| 264 |
|
| 265 |
<p> |
| 266 |
Have you noticed how many new filesystems are now available for Linux these |
| 267 |
days? Not only ReiserFS, but also SGI's XFS and IBM's own JFS (in source form) |
| 268 |
are now available for Linux. What an incredible selection! And, of course, we |
| 269 |
also have the Coda filesystem as well as good old ext2. As usual, choice is an |
| 270 |
excellent thing. In this collection of tips, we'll be looking at another area |
| 271 |
where we have lots of freedom -- how to organize partitions on disk. Regardless |
| 272 |
of which new-fangled filesystem you are using, good partition layout is |
| 273 |
essential. Here are three tips that will help to keep things organized. |
| 274 |
</p> |
| 275 |
|
| 276 |
</body> |
| 277 |
</section> |
| 278 |
<section> |
| 279 |
<title>Don't partition the entire drive</title> |
| 280 |
<body> |
| 281 |
|
| 282 |
<p> |
| 283 |
These days, new machines often have 20 or 34 gigabytes of storage on a single |
| 284 |
drive. These drives are great, but they create a new problem: how exactly do |
| 285 |
you partition these things? Many of us can only conceive of filling up 12 GB, |
| 286 |
and that's if we actually tried to fill things up. |
| 287 |
</p> |
| 288 |
|
| 289 |
<p> |
| 290 |
Instead of partitioning the entire drive during installation, you may want to |
| 291 |
consider partitioning only the portion of the drive that you know you will |
| 292 |
actually use. Later, when you've figured out how to use the 22 GB of free space |
| 293 |
sitting at the end of your drive, you'll have a better idea of how to partition |
| 294 |
it. Then, you can fire up <c>fdisk</c> or <c>cfdisk</c> and create a partition |
| 295 |
that meets your exact needs. For now, create partitions that are large enough |
| 296 |
to hold your current files, plus allow for future growth. Don't worry, the free |
| 297 |
space at the end of your drive will still be there when you need it. |
| 298 |
</p> |
| 299 |
|
| 300 |
</body> |
| 301 |
</section> |
| 302 |
<section> |
| 303 |
<title>Partition for backups</title> |
| 304 |
<body> |
| 305 |
|
| 306 |
<p> |
| 307 |
My second organizational tip will help your backups go more smoothly. If you |
| 308 |
are going to regularly back up a portion of your file system tree, it's a very |
| 309 |
good idea to place this data on a separate partition. Why? Because many copying |
| 310 |
and archiving tools have a special option for not crossing partition boundaries |
| 311 |
(such as <c>cp</c>'s <c>-x</c> option), which will make it easy to select only |
| 312 |
the files you want. Also, you can select a size for this partition so that it |
| 313 |
is close to capacity of your backup media. That way, you'll never have to worry |
| 314 |
about filling up a tape, and you can monitor how close you are to filling up |
| 315 |
your backup media by using the <c>df</c> command to see how much space is left |
| 316 |
on that particular partition. Then, you can track your storage and backup needs |
| 317 |
and plan accordingly. |
| 318 |
</p> |
| 319 |
|
| 320 |
</body> |
| 321 |
</section> |
| 322 |
<section> |
| 323 |
<title>Partition to reduce fragmentation</title> |
| 324 |
<body> |
| 325 |
|
| 326 |
<p> |
| 327 |
At the beginning of this article, I mentioned all the fancy new journaled |
| 328 |
filesystems now available for Linux. Amid all the excitement, it's easy to |
| 329 |
forget our old friend, the ext2 filesystem. ext2 does have some drawbacks; it |
| 330 |
is not extremely robust, for example. However, one thing it does excel at |
| 331 |
(especially when compared to Microsoft's NTFS) is keeping fragmentation to a |
| 332 |
minimum. If you don't know, file fragmentation occurs when there is not enough |
| 333 |
contiguous space on a filesystem to store an entire file. The result? The file |
| 334 |
is broken into non-contiguous "fragments," which are stored on disk. When this |
| 335 |
file is accessed, the hard drive's head needs to jump all over the place to |
| 336 |
read in the entire file. This slows down I/O, adding additional seeks to the |
| 337 |
reading process. |
| 338 |
</p> |
| 339 |
|
| 340 |
<p> |
| 341 |
OK, you may ask, what's the big deal? After all, ext2 filesystems take a long |
| 342 |
time to exhibit signs of fragmentation. However, I would argue that |
| 343 |
fragmentation is still a big problem, because although ext2 does not get |
| 344 |
fragmented easily, fragmentation is a one-way, cumulative process. That is, |
| 345 |
while ext2 fragments slowly, it cannot defragment itself. In other words, any |
| 346 |
often-modified ext2 filesystem will gradually get more and more fragmented, and |
| 347 |
thus slower. Even worse, there are no production-quality ext2 filesystem |
| 348 |
defragmenting programs currently available. This means that fragmentation is |
| 349 |
guaranteed to get worse over time, and the only way to fix it is to wipe the |
| 350 |
filesystem clean, and restore all the original files from a backup. That's a |
| 351 |
pretty involved and time-consuming process. So, how can the problem of |
| 352 |
fragmentation be dramatically reduced and contained? I'll cover all the juicy |
| 353 |
details in my next tip. See you then! |
| 354 |
</p> |
| 355 |
|
| 356 |
</body> |
| 357 |
</section> |
| 358 |
<section> |
| 359 |
<title>Resources</title> |
| 360 |
<body> |
| 361 |
|
| 362 |
<ul> |
| 363 |
<li> |
| 364 |
In <uri link="/doc/en/articles/partitioning-p1.xml">Partitioning in action: |
| 365 |
Moving /home</uri>, I show you step-by-step how to move <path>/home</path> |
| 366 |
to a new partition. |
| 367 |
</li> |
| 368 |
<li> |
| 369 |
In <uri link="/doc/en/articles/partitioning-p2.xml">Partitioning in |
| 370 |
action</uri>, I show you step-by-step how to move <path>/var</path> and |
| 371 |
<path>/tmp</path> to a new partition. |
| 372 |
</li> |
| 373 |
<li> |
| 374 |
See <uri link="/doc/en/articles/maximum-swappage.xml">Maximum |
| 375 |
swappage</uri>, another tip by Daniel, where he shows how to dramatically |
| 376 |
increase swap performance under Linux. |
| 377 |
</li> |
| 378 |
<li> |
| 379 |
Check out the <uri link="http://tldp.org/docs.html#howto">howtos</uri> at |
| 380 |
the <uri link="http://tldp.org">Linux Documentation Project</uri>. |
| 381 |
</li> |
| 382 |
</ul> |
| 383 |
|
| 384 |
</body> |
| 385 |
</section> |
| 386 |
<section> |
| 387 |
<title>About the author</title> |
| 388 |
<body> |
| 389 |
|
| 390 |
<p> |
| 391 |
Daniel Robbins lives in Albuquerque, New Mexico. He was the President/CEO of |
| 392 |
Gentoo Technologies Inc., the Chief Architect of the Gentoo Project and is a |
| 393 |
contributing author of several books published by MacMillan: Caldera OpenLinux |
| 394 |
Unleashed, SuSE Linux Unleashed, and Samba Unleashed. Daniel has been involved |
| 395 |
with computers in some fashion since the second grade when he was first exposed |
| 396 |
to the Logo programming language and a potentially lethal dose of Pac Man. This |
| 397 |
probably explains why he has since served as a Lead Graphic Artist at SONY |
| 398 |
Electronic Publishing/Psygnosis. Daniel enjoys spending time with his wife Mary |
| 399 |
and his new baby daughter, Hadassah. You can contact Daniel at |
| 400 |
<mail>drobbins@g.o</mail>. |
| 401 |
</p> |
| 402 |
|
| 403 |
</body> |
| 404 |
</section> |
| 405 |
</chapter> |
| 406 |
</guide> |
| 407 |
|
| 408 |
|
| 409 |
|
| 410 |
1.1 xml/htdocs/doc/en/articles/partitioning-p1.xml |
| 411 |
|
| 412 |
file : http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/partitioning-p1.xml?rev=1.1&content-type=text/x-cvsweb-markup&cvsroot=gentoo |
| 413 |
plain: http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/partitioning-p1.xml?rev=1.1&content-type=text/plain&cvsroot=gentoo |
| 414 |
|
| 415 |
Index: partitioning-p1.xml |
| 416 |
=================================================================== |
| 417 |
<?xml version="1.0" encoding="UTF-8"?> |
| 418 |
<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
| 419 |
<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/articles/partitioning-p1.xml,v 1.1 2005/08/18 12:59:17 neysx Exp $ --> |
| 420 |
|
| 421 |
<guide link="/doc/en/articles/partitioning-p1.xml" lang="en"> |
| 422 |
<title>Partitioning in action, Part 1</title> |
| 423 |
|
| 424 |
<author title="Author"> |
| 425 |
<mail link="drobbins@g.o">Daniel Robbins</mail> |
| 426 |
</author> |
| 427 |
<author title="Editor"> |
| 428 |
<mail link="jackdark@×××××.com">Joshua Saddler</mail> |
| 429 |
</author> |
| 430 |
|
| 431 |
<abstract> |
| 432 |
In this new series of tips, Daniel Robbins shows you how to change partition |
| 433 |
layout on a running system. He'll also cover several tricks of the trade to |
| 434 |
minimize downtime and avoid making costly mistakes. In this particular tip, |
| 435 |
he'll show you how to move /home to another partition. |
| 436 |
</abstract> |
| 437 |
|
| 438 |
<!-- The original version of this article was first published on IBM |
| 439 |
developerWorks, and is property of Westtech Information Services. This |
| 440 |
document is an updated version of the original article, and contains |
| 441 |
various improvements made by the Gentoo Linux Documentation team --> |
| 442 |
|
| 443 |
<version>1.0</version> |
| 444 |
<date>2005-08-15</date> |
| 445 |
|
| 446 |
<chapter> |
| 447 |
<title>Moving /home</title> |
| 448 |
<section> |
| 449 |
<title>Introduction</title> |
| 450 |
<body> |
| 451 |
|
| 452 |
<note> |
| 453 |
The original version of this article was first published on IBM developerWorks, |
| 454 |
and is property of Westtech Information Services. This document is an updated |
| 455 |
version of the original article, and contains various improvements made by the |
| 456 |
Gentoo Linux Documentation team. |
| 457 |
</note> |
| 458 |
|
| 459 |
<p> |
| 460 |
The partition <path>/home</path> is one of the most-often-moved partitions. |
| 461 |
Sometimes, all the space in <path>/home</path> becomes exhausted, and an |
| 462 |
additional hard drive is required. Other times, <path>/home</path> is set up as |
| 463 |
part of the root partition, and it may need to be moved to improve performance |
| 464 |
or facilitate backup. Whatever the case, I'll show you how to move |
| 465 |
<path>/home</path> safely and efficiently. |
| 466 |
</p> |
| 467 |
|
| 468 |
<warn> |
| 469 |
The following technique describes how to move a partition(s). Although this |
| 470 |
technique is designed so that you can "back out" of a failed partition move, it |
| 471 |
doesn't protect against user error. In other words, any time that you format |
| 472 |
partitions or copy large numbers of files, there's a possibility that you will |
| 473 |
type the wrong thing, causing lots of data to be destroyed. For this reason, |
| 474 |
it's highly recommended that you <e>take appropriate steps to back up all |
| 475 |
critical files before proceeding</e>. |
| 476 |
</warn> |
| 477 |
|
| 478 |
<p> |
| 479 |
Now that you're prepared, we're ready to start moving <path>/home</path>. The |
| 480 |
exact steps you will take depend on whether <path>/home</path> currently |
| 481 |
resides on its own separate partition, or whether it is located on the root |
| 482 |
partition. Keep this in mind as we go through the steps (I'll make notes where |
| 483 |
necessary). Right now, if you are moving <path>/home</path> to a new hard |
| 484 |
drive, it should be physically installed in your system. |
| 485 |
</p> |
| 486 |
|
| 487 |
<p> |
| 488 |
If you are moving <path>/home</path> to an existing partition (it doesn't need |
| 489 |
to be ext2, as long as the target primary or extended partition exists), you |
| 490 |
can proceed to <uri link="#step2">step 2</uri>. |
| 491 |
</p> |
| 492 |
|
| 493 |
</body> |
| 494 |
</section> |
| 495 |
<section> |
| 496 |
<title>Create a new partition, if necessary</title> |
| 497 |
<body> |
| 498 |
|
| 499 |
<p> |
| 500 |
If the new partition doesn't exist yet, you'll need to create it using |
| 501 |
<c>cfdisk</c> (preferred) or <c>fdisk</c>. If the partition doesn't reside on |
| 502 |
your first drive, remember to specify the name of the device as the first |
| 503 |
argument to <c>cfdisk</c> or <c>fdisk</c>. After creating the appropriate |
| 504 |
primary or extended partition, you should reboot so that the partition table |
| 505 |
can be reread correctly. This is the only time you will need to reboot the |
| 506 |
system. |
| 507 |
</p> |
| 508 |
|
| 509 |
</body> |
| 510 |
</section> |
| 511 |
</chapter> |
| 512 |
|
| 513 |
<chapter id="step2"> |
| 514 |
<title>Create a filesystem on the new partition</title> |
| 515 |
<section> |
| 516 |
<body> |
| 517 |
|
| 518 |
<p> |
| 519 |
To create a filesystem on the new partition, first make sure you know the exact |
| 520 |
device name for the new partition (for example, <path>/dev/sda5</path>). If |
| 521 |
you're not sure of the exact device name, stop now and double-check! Then type |
| 522 |
the following, as root: |
| 523 |
</p> |
| 524 |
|
| 525 |
<pre caption="Creating the filesystem"> |
| 526 |
# <i>mkfs.ext2 /dev/???</i> |
| 527 |
</pre> |
| 528 |
|
| 529 |
<p> |
| 530 |
In the above and following code samples, <path>???</path> should be replaced |
| 531 |
with the target partition name. After executing this command, the target |
| 532 |
partition will contain an empty ext2 filesystem. |
| 533 |
</p> |
| 534 |
|
| 535 |
</body> |
| 536 |
</section> |
| 537 |
</chapter> |
| 538 |
|
| 539 |
<chapter> |
| 540 |
<title>Mount the new filesystem in /mnt</title> |
| 541 |
<section> |
| 542 |
<body> |
| 543 |
|
| 544 |
<p> |
| 545 |
Create a directory called <path>/mnt/newpart</path>, and then mount the new |
| 546 |
partition there: |
| 547 |
</p> |
| 548 |
|
| 549 |
<pre caption="Mounting the partition"> |
| 550 |
# <i>mount /dev/??? /mnt/newpart</i> |
| 551 |
</pre> |
| 552 |
|
| 553 |
</body> |
| 554 |
</section> |
| 555 |
</chapter> |
| 556 |
|
| 557 |
<chapter> |
| 558 |
<title>Drop to single-user mode</title> |
| 559 |
<section> |
| 560 |
<body> |
| 561 |
|
| 562 |
<p> |
| 563 |
I delayed this step as long as possible to maximize system availability, but we |
| 564 |
now must drop into single-user mode, and copy files from <path>/home</path> to |
| 565 |
<path>/mnt/newpart</path>. You shouldn't have any files open in |
| 566 |
<path>/home</path>, and entering single-user mode eliminates this possibility: |
| 567 |
</p> |
| 568 |
|
| 569 |
<pre caption="Entering single user mode"> |
| 570 |
# <i>init 1</i> |
| 571 |
</pre> |
| 572 |
|
| 573 |
<p> |
| 574 |
If prompted, enter the root password to perform system maintenance. You should |
| 575 |
now have a root shell. |
| 576 |
</p> |
| 577 |
|
| 578 |
</body> |
| 579 |
</section> |
| 580 |
</chapter> |
| 581 |
|
| 582 |
<chapter> |
| 583 |
<title>Change directories to /home and copy files</title> |
| 584 |
<section> |
| 585 |
<body> |
| 586 |
|
| 587 |
<p> |
| 588 |
Type the following: |
| 589 |
</p> |
| 590 |
|
| 591 |
<pre caption="Copying files"> |
| 592 |
# <i>cd /home</i> |
| 593 |
# <i>cp -ax * /mnt/newpart</i> |
| 594 |
</pre> |
| 595 |
|
| 596 |
<p> |
| 597 |
The <c>cp -ax</c> command recursively copies the contents of <path>/home</path> |
| 598 |
to <path>/mnt/newpart</path>, preserving all file attributes, and not crossing |
| 599 |
any mount points. After this command finishes, <path>/mnt/newpart</path> will |
| 600 |
contain an exact copy of all the files and directories currently in |
| 601 |
<path>/home</path>. If the old <path>/home</path> was on its own separate |
| 602 |
partition (listed on a separate line in <path>/etc/fstab</path>), go to <uri |
| 603 |
link="#step6a">step 6a</uri>. Otherwise, proceed to <uri link="#step6b">step |
| 604 |
6b</uri>. |
| 605 |
</p> |
| 606 |
|
| 607 |
</body> |
| 608 |
</section> |
| 609 |
</chapter> |
| 610 |
|
| 611 |
<chapter> |
| 612 |
<title>Use the new partition</title> |
| 613 |
<section id="step6a"> |
| 614 |
<title>6a: /home on its own partition</title> |
| 615 |
<body> |
| 616 |
|
| 617 |
|
| 618 |
|
| 619 |
1.1 xml/htdocs/doc/en/articles/partitioning-p2.xml |
| 620 |
|
| 621 |
file : http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/partitioning-p2.xml?rev=1.1&content-type=text/x-cvsweb-markup&cvsroot=gentoo |
| 622 |
plain: http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/partitioning-p2.xml?rev=1.1&content-type=text/plain&cvsroot=gentoo |
| 623 |
|
| 624 |
Index: partitioning-p2.xml |
| 625 |
=================================================================== |
| 626 |
<?xml version="1.0" encoding="UTF-8"?> |
| 627 |
<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
| 628 |
<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/articles/partitioning-p2.xml,v 1.1 2005/08/18 12:59:17 neysx Exp $ --> |
| 629 |
|
| 630 |
<guide link="/doc/en/articles/partitioning-p2.xml" lang="en"> |
| 631 |
<title>Partitioning in action, Part 2</title> |
| 632 |
|
| 633 |
<author title="Author"> |
| 634 |
<mail link="drobbins@g.o">Daniel Robbins</mail> |
| 635 |
</author> |
| 636 |
<author title="Editor"> |
| 637 |
<mail link="jackdark@×××××.com">Joshua Saddler</mail> |
| 638 |
</author> |
| 639 |
|
| 640 |
<abstract> |
| 641 |
In this second tip on changing partition layout on a running system, Daniel |
| 642 |
Robbins shows you how to move /tmp and /var to their own shared partition. He |
| 643 |
also covers several tricks of the trade to minimize downtime and avoid making |
| 644 |
costly mistakes. |
| 645 |
</abstract> |
| 646 |
|
| 647 |
<!-- The original version of this article was first published on IBM |
| 648 |
developerWorks, and is property of Westtech Information Services. This |
| 649 |
document is an updated version of the original article, and contains |
| 650 |
various improvements made by the Gentoo Linux Documentation team --> |
| 651 |
|
| 652 |
<version>1.0</version> |
| 653 |
<date>2005-08-15</date> |
| 654 |
|
| 655 |
<chapter> |
| 656 |
<title>Consolidating data</title> |
| 657 |
<section> |
| 658 |
<title>Introduction</title> |
| 659 |
<body> |
| 660 |
|
| 661 |
<note> |
| 662 |
The original version of this article was first published on IBM developerWorks, |
| 663 |
and is property of Westtech Information Services. This document is an updated |
| 664 |
version of the original article, and contains various improvements made by the |
| 665 |
Gentoo Linux Documentation team. |
| 666 |
</note> |
| 667 |
|
| 668 |
<p> |
| 669 |
In my <uri link="/doc/en/articles/partitioning-p1.xml">last tip</uri>, we |
| 670 |
successfully moved <path>/home</path> to a new partition. Now, it's time to |
| 671 |
learn how to consolidate often-modified files onto a new partition. Why would |
| 672 |
we want to do this? Here's an example. Often-modified files contribute heavily |
| 673 |
to fragmentation. One of the best ways to contain fragmentation is to store |
| 674 |
often-modified files on their own partition. That way, the other partitions are |
| 675 |
unaffected by the fragmentation caused by the heavily modified files. In |
| 676 |
concept, this is easy to understand, but how do you actually go about doing it? |
| 677 |
</p> |
| 678 |
|
| 679 |
<p> |
| 680 |
First, you must create a new partition for the specific purpose of storing |
| 681 |
frequently modified files. You might want to locate this partition on a |
| 682 |
separate disk to enhance performance. Then, I'll walk you through the steps |
| 683 |
required to move both <path>/tmp</path> and <path>/var</path> to this new |
| 684 |
partition. |
| 685 |
</p> |
| 686 |
|
| 687 |
<warn> |
| 688 |
The following technique describes how to move a partition(s). Although this |
| 689 |
technique is designed so that you can "back out" of a failed partition move, it |
| 690 |
doesn't protect against user error. In other words, any time that you format |
| 691 |
partitions or copy large numbers of files, there's a possibility that you will |
| 692 |
type the wrong thing, causing lots of data to be destroyed. For this reason, |
| 693 |
it's highly recommended that you <e>take appropriate steps to back up all |
| 694 |
critical files before proceeding</e>. |
| 695 |
</warn> |
| 696 |
|
| 697 |
</body> |
| 698 |
</section> |
| 699 |
<section> |
| 700 |
<title>Create a filesystem on the new partition</title> |
| 701 |
<body> |
| 702 |
|
| 703 |
<p> |
| 704 |
The first step of this process is to create a new partition that's big enough |
| 705 |
to hold <path>/var</path> and <path>/tmp</path>, with a little extra space left |
| 706 |
over. You'll need either an additional drive, or a spare (unused) partition |
| 707 |
that will house the often-modified files. If you do need to use <c>fdisk</c> or |
| 708 |
<c>cfdisk</c> to create the partition, you'll need to reboot once. Then, it's |
| 709 |
time to format the new partition as follows (it's OK to be in multiuser mode |
| 710 |
while you do this; I'll let you know when to switch to single-user): |
| 711 |
</p> |
| 712 |
|
| 713 |
<pre caption="Creating the filesystem"> |
| 714 |
# <i>mkfs.ext2 /dev/???</i> |
| 715 |
</pre> |
| 716 |
|
| 717 |
</body> |
| 718 |
</section> |
| 719 |
</chapter> |
| 720 |
|
| 721 |
<chapter> |
| 722 |
<title>Mount it to /mnt/rwstorage</title> |
| 723 |
<section> |
| 724 |
<body> |
| 725 |
|
| 726 |
<p> |
| 727 |
As in my previous tip, <path>???</path> should be replaced with the device name |
| 728 |
for the new, empty partition that you are creating. Accidentally typing the |
| 729 |
wrong name will destroy data on an existing partition, so be careful! After |
| 730 |
typing this command, you'll have a brand-new ext2 filesystem on the new |
| 731 |
partition. We're almost ready to mount it, but first, let's make a new mount |
| 732 |
point. |
| 733 |
</p> |
| 734 |
|
| 735 |
<pre caption="Creating the mount point"> |
| 736 |
# <i>mkdir /mnt/rwstorage</i> |
| 737 |
</pre> |
| 738 |
|
| 739 |
<p> |
| 740 |
I chose the name <path>rwstorage</path> to remind us that this particular |
| 741 |
partition is going to be specifically used to house files that are read from |
| 742 |
and written to frequently. To mount the partition, type: |
| 743 |
</p> |
| 744 |
|
| 745 |
<pre caption="Mounting the partition"> |
| 746 |
# <i>mount /dev/??? /mnt/rwstorage</i> |
| 747 |
</pre> |
| 748 |
|
| 749 |
</body> |
| 750 |
</section> |
| 751 |
</chapter> |
| 752 |
|
| 753 |
<chapter> |
| 754 |
<title>Creating a new /tmp</title> |
| 755 |
<section> |
| 756 |
<body> |
| 757 |
|
| 758 |
<p> |
| 759 |
The partition is now mounted and we're ready to create our new |
| 760 |
<path>/tmp</path> directory: |
| 761 |
</p> |
| 762 |
|
| 763 |
<pre caption="Creating the new /tmp"> |
| 764 |
# <i>cd /mnt/rwstorage</i> |
| 765 |
# <i>mkdir tmp</i> |
| 766 |
# <i>chmod 1777 tmp</i> |
| 767 |
</pre> |
| 768 |
|
| 769 |
</body> |
| 770 |
</section> |
| 771 |
</chapter> |
| 772 |
|
| 773 |
<chapter> |
| 774 |
<title>Drop to single-user mode</title> |
| 775 |
<section> |
| 776 |
<body> |
| 777 |
|
| 778 |
<p> |
| 779 |
Our new directory at <path>/mnt/rwstorage/tmp</path> has the right permissions |
| 780 |
for a temporary directory. Now, drop to single-user mode, since we must copy |
| 781 |
over <path>/var</path>. As usual, we've delayed our drop to single-user mode to |
| 782 |
the last possible moment. Right now, we don't want any programs reading or |
| 783 |
writing files in <path>/var</path>, so we have to stop all daemons, disconnect |
| 784 |
all users, and do some quick maintenance by typing: |
| 785 |
</p> |
| 786 |
|
| 787 |
<pre caption="Entering single-user mode"> |
| 788 |
# <i>init 1</i> |
| 789 |
</pre> |
| 790 |
|
| 791 |
<p> |
| 792 |
If you're prompted to enter a password to perform system maintanance, do so. |
| 793 |
You should now have a root shell, and all unnecessary daemons will be stopped. |
| 794 |
Create a new location for our <path>/var</path> files by typing: |
| 795 |
</p> |
| 796 |
|
| 797 |
<pre caption="Creating the new directory"> |
| 798 |
# <i>cd /mnt/rwstorage</i> |
| 799 |
# <i>mkdir var</i> |
| 800 |
</pre> |
| 801 |
|
| 802 |
</body> |
| 803 |
</section> |
| 804 |
</chapter> |
| 805 |
|
| 806 |
<chapter> |
| 807 |
<title>Copy /var</title> |
| 808 |
<section> |
| 809 |
<body> |
| 810 |
|
| 811 |
<p> |
| 812 |
Default permissions on our new <path>/mnt/newstorage/var</path> directory |
| 813 |
should be correct, so now we're ready to copy all of our original |
| 814 |
<path>/var</path> data over to the new partition: |
| 815 |
</p> |
| 816 |
|
| 817 |
<pre caption="Copying the data"> |
| 818 |
# <i>cd /var </i> |
| 819 |
# <i>cp -ax * /mnt/rwstorage/var</i> |
| 820 |
</pre> |
| 821 |
|
| 822 |
</body> |
| 823 |
</section> |
| 824 |
</chapter> |
| 825 |
|
| 826 |
|
| 827 |
|
| 828 |
-- |
| 829 |
gentoo-doc-cvs@g.o mailing list |
Archives