# Azamat H. Hackimov , 2009. msgid "" msgstr "" "Project-Id-Version: \n" "POT-Creation-Date: 2011-09-05 14:11+0600\n" "PO-Revision-Date: 2009-10-17 20:20+0600\n" "Last-Translator: Azamat H. Hackimov \n" "Language-Team: Russian \n" "Language: ru\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=UTF-8\n" "Content-Transfer-Encoding: 8bit\n" "Plural-Forms: nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n" "%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);\n" "X-Generator: Lokalize 1.0\n" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):6 msgid "Advanced Filesystem Implementor's Guide : Introducing ext3" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(author:title):8 msgid "Author" msgstr "автор" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(mail:link):9 msgid "drobbins@gentoo.org" msgstr "drobbins@gentoo.org" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(mail):9 msgid "Daniel Robbins" msgstr "" #. The original version of this article was first published on IBM #. developerWorks, and is property of Westtech Information Services. This #. document is an updated version of the original article, and contains #. various improvements made by the Gentoo Linux Documentation team #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(abstract):20 msgid "" "With the 2.4 release of Linux come a host of new filesystem possibilities, " "including Reiserfs, XFS, GFS, and others. These filesystems sound cool, but " "what exactly can they do, what are they good at, and exactly how do you go " "about safely using them in a production Linux environment? Daniel Robbins " "answers these questions by showing you how to set up these new advanced " "filesystems under Linux 2.4. In this installment, Daniel takes a look at " "ext3, a new improved version of ext2 with journaling capabilities." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(version):30 msgid "1.1" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(date):31 msgid "2005-10-09" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):34 msgid "Introduction" msgstr "Введение" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):38 msgid "" "In the past few installments, we've taken a bit of a detour by looking at " "non-traditional filesystems such as tmpfs and devfs. Now, it's time to get " "back to disk-based filesystems, and we do this by taking a look at ext3. The " "ext3 filesystem, designed by Dr. Stephen Tweedie, is built on the framework " "of the existing ext2 filesystem; in fact, ext3 is very similar to ext2 " "except for one small (but important) difference -- it supports journaling. " "Yet even with this small addition, I think you'll find that that ext3 has " "several surprising and intriguing capabilities. In this article, I'll give " "you a good understanding of how ext3 compares to the other journaling " "filesystems currently available. In my next article, we'll get ext3 up and " "running." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):56 msgid "Understanding Ext3" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):60 msgid "" "So, how does ext3 compare to ReiserFS? In previous articles, I explained how " "ReiserFS is well suited to handling small files (under 4K), and in certain " "situations, ReiserFS' small file performance is ten to fifteen times greater " "than that of ext2 and ext3. However, while ReiserFS has many strengths, it " "also has weaknesses. In the current implementation of ReiserFS (version " "3.6), certain file access patterns can actually result in significantly " "worse performance than ext2 and ext3, particularly when reading large mail " "directories. Also, ReiserFS doesn't have a good track record of NFS " "compatibility and has poor sparse file performance. In contrast, ext3 is a " "very well-rounded filesystem. It's a lot like ext2; it's not going to give " "you the blazingly fast small-file performance that ReiserFS gives you, but " "it's not going to give you any unexpected performance or functionality " "hiccups either." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):75 msgid "" "One of the nice things about ext3 is that because it is based on the ext2 " "code, ext2 and ext3's on-disk format is identical; this means that a cleanly " "unmounted ext3 filesystem can be remounted as an ext2 filesystem with " "absolutely no problems. And that's not all. Thanks to the fact that ext2 and " "ext3 use identical metadata, it's possible to perform in-place ext2 to ext3 " "filesystem upgrades. Yes, you read that right. By upgrading a few key system " "utilities, installing a modern 2.4 kernel and typing in a single tune2fs " "command per filesystem, you can convert your existing ext2 servers into " "journaling ext3 systems. You can even do this while your ext2 filesystems " "are mounted. The transition is safe, reversible, and incredibly easy, and " "unlike a conversion to XFS, JFS, or ReiserFS, you don't need to back up and " "recreate your filesystems from scratch. Now, for a moment, consider the " "thousands of production ext2 servers in existence that are just minutes away " "from an ext3 upgrade; then, you'll have a good grasp of ext3's importance to " "the Linux community." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):93 msgid "" "If I had to describe ext3 in one word, I'd call it \"comfortable\". It's " "incredibly easy to ext3-enable an existing ext2 system, and after you do, " "you're not going to run into any unexpected performance quirks. And there's " "yet another way that ext3 excels in the comfort department; ext3 happens to " "be one of the most reliable journaled filesystems available for Linux, as I " "explain below." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):107 msgid "Ext3 reliability" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):112 msgid "" "In addition to being ext2-compatible, ext3 inherits other benefits by " "sharing ext2's metadata format. For one, ext3 users gain access to a rock-" "solid fsck tool. You'll recall that one of the points of using a journaling " "filesystem is to avoid the need for an exhaustive fsck in the first place; " "however if you do end up getting corrupt metadata, either from a flaky " "kernel, bad hard drive, or something else, you'll greatly appreciate the " "fact that ext3 inherits ext2's fsck. In contrast, ReiserFS' fsck is in its " "infancy, and fixing flaky metadata when it does show up can be a difficult " "and dangerous process." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):127 msgid "Metadata-only journaling" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):130 msgid "" "Interestingly, ext3 handles journaling very differently than ReiserFS and " "other journaling filesystems do. With ReiserFS, XFS, and JFS, the filesystem " "driver journals metadata, but makes no provisions for journaling data. With " "metadata-only journaling, your filesystem metadata is going to be rock " "solid, and you will probably never need to perform an exhaustive fsck. " "However, unexpected reboots and system lock-ups can result in significant " "corruption of recently-modified data. Ext3 uses a couple of innovative " "solutions to avoid these problems, which we'll look at in a bit." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):141 msgid "" "But first, it's important to understand exactly how metadata-only journaling " "could end up biting you. As an example, let's say that you were modifying a " "file called /tmp/myfile.txt when the machine unexpectedly locked up, forcing " "a reboot. If you were using a metadata-only journaling filesystem such as " "ReiserFS, XFS or JFS, your filesystem metadata would be easily repaired, " "thanks to the metadata journal, and you wouldn't need to sit through a " "laborious fsck." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):150 msgid "" "However, there's the distinct possibility that when you load /tmp/myfile.txt " "into a text editor, your file will not simply be missing recent changes, but " "will contain a good amount of garbage and may even be completely unreadable. " "This isn't something that will always happen, but it could happen and often " "does." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):158 msgid "" "Here's why. Typical journaled filesystems like ReiserFS, XFS, and JFS take " "extra special care of metadata, but don't pay too much attention to data. In " "our above example, the filesystem driver was in the process of modifying " "several filesystem blocks. The filesystem driver updated the appropriate " "metadata, but didn't have time to flush the data from its caches to the new " "blocks on disk. Thus, when you loaded up /tmp/myfile.txt into a text editor, " "part or all of the file contained garbage -- blocks of data that didn't get " "initialized in time before the system locked up." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):175 msgid "The ext3 approach" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):179 msgid "" "Now that we have a good general understanding of this problem, let's look " "how ext3 implements journaling. In ext3, the journaling code uses a special " "API called the Journaling Block Device layer, or JBD. The JBD has been " "designed for the express purpose of implementing a journal on any kind of " "block device. Ext3 implements its journaling by \"hooking in\" to the JBD " "API. For example, the ext3 filesystem code will inform the JBD of " "modifications it is performing, and will also request permission from the " "JBD before modifying certain data on disk. By doing so, the JBD is given the " "appropriate opportunities to manage the journal on behalf of the ext3 " "filesystem driver. It's quite a nice arrangement, and because the JBD is " "being developed as a separate, generic entity, it could be used to add " "journaling capabilities to other filesystems in the future." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):194 msgid "" "Here are a couple of neat things about the JBD-managed ext3 journal. For " "one, ext3's journal is stored in an inode -- a file, basically. Depending on " "how you \"ext3-enable\" your filesystem, you may or may not be able to see " "this file, located at /.journal. Of course, by storing the journal in an " "inode, ext3 is able to add the needed journal to the filesystem without " "requiring incompatible extensions to the ext2 metadata. This is one of the " "key ways that an ext3 filesystem maintains backwards compatibility with ext2 " "metadata, and in turn, the ext2 filesystem driver." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):210 msgid "Different journaling approaches" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):214 msgid "" "Not surprisingly, it turns out that there are a number of ways to implement " "a journal. For example, a filesystem developer could design a journal that " "stores spans of bytes that need to be modified on the host filesystem. The " "advantage of this approach is that your journal would be able to store lots " "of tiny little modifications to the filesystem in a very efficient way, " "since it would only record the individual bytes that need to be modified and " "nothing more." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):223 msgid "" "JBD takes another, and in some ways better, approach. Rather than recording " "spans of bytes that must be changed, JBD stores the complete modified " "filesystem blocks themselves. The ext3 filesystem driver also uses this " "approach and stores complete replicas of the modified blocks (either 1K, 2K, " "or 4K) in memory to track pending IO operations. At first, this may seem a " "bit wasteful. After all, complete blocks contain modified data but may also " "contain unmodified (already on disk) data as well." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):233 msgid "" "The approach that the JBD uses is called physical journaling, which means " "that the JBD uses complete physical blocks as the underlying currency for " "implementing the journal. In contrast, the approach of only storing modified " "spans of bytes rather than complete blocks is called logical journaling, and " "is the approach used by XFS. Because ext3 uses physical journaling, an ext3 " "journal will have a larger relative on-disk footprint than, say, an XFS " "journal. But because ext3 uses complete blocks internally and in the " "journal, ext3 doesn't deal with as much complexity as it would if it were to " "implement logical journaling. In addition, the use of full blocks allows " "ext3 to perform some additional optimizations, such as \"squishing\" " "multiple pending IO operations within a single block into the same in-memory " "data structure. This, in turn, allows ext3 to write these multiple changes " "to disk in a single write operation, rather than many. In addition, because " "the literal block data is stored in memory, little or no massaging of the in-" "memory data is required before writing it to disk, greatly reducing CPU " "overhead." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):256 msgid "Ext3, protector of data" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):260 msgid "" "And now, we finally get to see how the ext3 filesystem effectively provides " "both metadata and data journaling, avoiding the data corruption problem I " "described earlier in this article. In fact, ext3 actually has two methods to " "ensure data and metadata integrity." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):267 msgid "" "Originally, ext3 was designed to perform full data and metadata journaling. " "In this mode (called \"data=journal\" mode), the JBD journals all changes to " "the filesystem, whether they are made to data or metadata. Because both data " "and metadata are journaled, JBD can use the journal to bring both metadata " "and data back to a consistent state. The drawback of full data journaling is " "that it can be slow, although you can reduce the performance penalty by " "setting up a relatively large journal." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):277 msgid "" "Recently, a new journaling mode has been added to ext3 that provides the " "benefits of full journaling but without introducing a severe performance " "penalty. This new mode works by journaling metadata only. However, the ext3 " "filesystem driver keeps track of the particular data blocks that correspond " "with each metadata update, grouping them into a single entity called a " "transaction. When a transaction is applied to the filesystem proper, the " "data blocks are written to disk first. Once they are written, the metadata " "changes are then written to the journal. By using this technique (called " "\"data=ordered\" mode), ext3 can provide data and metadata consistency, even " "though only metadata changes are recorded in the journal. ext3 uses this " "mode by default." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):295 msgid "Conclusion" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):299 msgid "" "These days, a lot of people are trying to determine which Linux journaling " "filesystem is \"best\". In truth, there is no one \"right\" filesystem for " "every application; each one has its own strengths. This is one of the " "benefits from having so many next-generation Linux filesystems from which to " "choose. So, instead of picking an arbitrary \"best\" filesystem and using it " "for every conceivable application, it's far preferable to understand each " "filesystem's strengths and weaknesses so that you can make an educated " "decision as to which one to use." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):310 msgid "" "Ext3 has a number of strengths. It has been designed to be extremely easy to " "deploy. It's based on the solid ext2 filesystem code and it inherits a great " "fsck tool. And ext3's journaling capabilities have been specially designed " "to ensure the integrity of both metadata and data. All in all, ext3 is a " "truly great filesystem, and a worthy successor to the now-venerable ext2 " "filesystem. Join me in my next article, when we get ext3 up and running. " "Until then, you may want to check out the following resources." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):325 msgid "Resources" msgstr "" #. Let's link to parts 1-6 once they've been GuideXMLified #.

#. Read Daniel's other articles in this series, where he describes: #.

#. #.
    #.
  • The benefits of journaling and ReiserFS (Part 1)
    • #.
  • Setting up a ReiserFS system (Part 2)
    • #.
  • Using the tmpfs virtual memory filesystem and bind mounts (Part 3)
    • #.
  • The benefits of devfs, the device management filesystem (Part 4)
    • #.
  • Beginning the conversion to devfs (Part 5)
    • #.
  • Completing the conversion to devfs using an init wrapper (Part 6)
    • #.
#: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):344 msgid "" "Read a complete transcript of Dr. Stephen Tweedie's Ext3, " "Journaling Filesystem presentation, which was featured at the Ottawa Linux " "Symposium in July 2000." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):352 msgid "" "Find out more about using ext3 with 2.4 kernels at Andrew Morton's ext3 for 2.4 " "page. Andrew Morton is the man responsible for porting ext3 to the 2.4 " "kernel, and provided invaluable assistance in writing this article. If you " "can't wait until my next article, Andrew has a very nice ext3 and 2.4 usage page that will show you how to get ext3 up and running on your system in no " "time." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):363 msgid "" "To keep abreast of the latest ext3 developments, be sure to visit the ext3-users mailing " "list archive. Of course, you can also subscribe." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):370 msgid "" "Take Daniel Robbins' free JFS fundamentals tutorial on " "developerWorks." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):376 msgid "" "Browse more Linux resources on developerWorks." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):381 msgid "" "Browse more Open source resources on developerWorks." msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(title):392 msgid "About the author" msgstr "" #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(p):396 msgid "" "Residing in Albuquerque, New Mexico, Daniel Robbins is the President/CEO of " "Gentoo Technologies, Inc., the creator of Gentoo Linux, an advanced Linux " "for the PC, and the Portage system, a next-generation ports system for " "Linux. He has also served as a contributing author for the Macmillan books " "Caldera OpenLinux Unleashed, SuSE Linux Unleashed, and Samba Unleashed. " "Daniel has been involved with computers in some fashion since the second " "grade, when he was first exposed to the Logo programming language as well as " "a potentially dangerous dose of Pac Man. This probably explains why he has " "since served as a Lead Graphic Artist at SONY Electronic Publishing/" "Psygnosis. Daniel enjoys spending time with his wife, Mary, and their " "daughter, Hadassah. You can contact Daniel at drobbins@gentoo.org." msgstr "" #. Place here names of translator, one per line. Format should be NAME; ROLE; E-MAIL #: ../../gentoo/xml/htdocs/doc/en/articles/afig-ct-ext3-intro.xml(None):0 msgid "translator-credits" msgstr ""