[linuxjf/JF.git] / docs / kernel-docs-2.6 / filesystems / ext4.txt

=========================================================
¤³¤ì¤Ï¡¢
Linux-2.6.31.1/Documentation/filesystems/ext4.txt ¤ÎÏÂÌõ
¤Ç¤¹¡£
ËÝÌõÃÄÂΡ§ JF ¥×¥í¥¸¥§¥¯¥È < http://www.linux.or.jp/JF/ >
¹¹¿·Æü ¡§ 2009/07/25
ËÝÌõ¼Ô ¡§ Seiji Kaneko < skaneko at mbn dot or dot jp >
ººÆÉ¼Ô : Hiroshi Suzuki <setter at reset dot jp>
=========================================================

#Ext4 Filesystem
#===============
Ext4 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à
====================

#Ext4 is an an advanced level of the ext3 filesystem which incorporates
#scalability and reliability enhancements for supporting large filesystems
#(64 bit) in keeping with increasing disk capacities and state-of-the-art
#feature requirements.
ext4 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Ï¡¢ext3 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Î¼¡À¤Âå¤Î¿å½à¤È¤·¤Æ¡¢¥Ç¥£¥¹
¥¯ÍÆÎ̤ÎÁý²Ã¤Ëȼ¤¦µðÂç¤Ê¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à (64bit) ¤ò°·¤¦¤Î¤ËɬÍפʳÈÄ¥À­¤È
¿®ÍêÀ­¤ò¸þ¾å¤·¡¢ºÇ¿·¤Îµ¡Ç½Í×µá¤Ë±þ¤¨¤¿¤â¤Î¤Ç¤¹¡£

#Mailing list:  linux-ext4@vger.kernel.org
¥á¡¼¥ê¥ó¥°¥ê¥¹¥È:  linux-ext4@vger.kernel.org
#Web site:      http://ext4.wiki.kernel.org
¥¦¥§¥Ö¥µ¥¤¥È:   http://ext4.wiki.kernel.org


#1. Quick usage instructions:
#===========================
1. ´Êñ¤ÊÍøÍÑÊýË¡
=================

#Note: More extensive information for getting started with ext4 can be
#      found at the ext4 wiki site at the URL:
#      http://ext4.wiki.kernel.org/index.php/Ext4_Howto
Ãíµ­:   ext4 ¤ò¤Ï¤¸¤á¤ë¤ËÅö¤¿¤Ã¤Æ¤Î¤µ¤é¤Ë¾ÜºÙ¤ÊÀâÌÀ¤Ï¡¢²¼µ­ URL ¤Î ext4 Wiki
        ¥µ¥¤¥È¤Ë¤¢¤ê¤Þ¤¹¡£
      http://ext4.wiki.kernel.org/index.php/Ext4_Howto

#  - Compile and install the latest version of e2fsprogs (as of this
#    writing version 1.41.3) from:
  - ºÇ¿·¤Î e2fsprogs (¸½ºß¥Ð¡¼¥¸¥ç¥ó 1.41.3) ¤ò°Ê²¼¤«¤éÆþ¼ê¤·¡¢¥³¥ó¥Ñ¥¤¥ë¡¦
    ¥¤¥ó¥¹¥È¡¼¥ë¤·¤Æ¤¯¤À¤µ¤¤¡£

    http://sourceforge.net/project/showfiles.php?group_id=2406
        
#       or
        ¤Þ¤¿¤Ï

    ftp://ftp.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/

#       or grab the latest git repository from:
        ¤Þ¤¿¤Ï°Ê²¼¤«¤éºÇ¿·¤Î git ¥ê¥Ý¥¸¥È¥ê¤òÆþ¼ê¤·¤Æ¤¯¤À¤µ¤¤¡£

    git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git

#  - Note that it is highly important to install the mke2fs.conf file
#    that comes with the e2fsprogs 1.41.x sources in /etc/mke2fs.conf. If
#    you have edited the /etc/mke2fs.conf file installed on your system,
#    you will need to merge your changes with the version from e2fsprogs
#    1.41.x.
   - e2fsprogs 1.41.x ¥½¡¼¥¹ÉÕ°¤Î mke2fs.conf ¥Õ¥¡¥¤¥ë¤ò /etc/mke2fs.conf
     ¤Ë¥¤¥ó¥¹¥È¡¼¥ë¤¹¤ë¤³¤È¤Ï¤È¤Æ¤â½ÅÍפǤ¹¡£¥·¥¹¥Æ¥à¤Ë¥¤¥ó¥¹¥È¡¼¥ë¤·¤Æ¤¢¤ë
     /etc/mke2fs.conf ¥Õ¥¡¥¤¥ë¤ò¤¹¤Ç¤ËÊÔ½¸¤·¤Æ¤¤¤ë¾ì¹ç¤Ï¡¢e2fsprogs 1.41.x
     ¤ÎÈǤΤâ¤Î¤Ë´û¸¤Î½¤Àµ¤ò¥Þ¡¼¥¸¤¹¤ëɬÍפ¬¤¢¤ê¤Þ¤¹¡£

#  - Create a new filesystem using the ext4 filesystem type:
   - ext4 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¥¿¥¤¥×¤òÍѤ¤¤Æ¿·µ¬¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤òºîÀ®¤·¤Þ¤¹¡£

        # mke2fs -t ext4 /dev/hda1

#    Or to configure an existing ext3 filesystem to support extents:
     ¤Þ¤¿¤Ï¡¢´û¸¤Î ext3 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤ò¥¨¥¯¥¹¥Æ¥ó¥È¤ò¥µ¥Ý¡¼¥È¤¹¤ë¤è¤¦Àß
     Äꤷ¤Þ¤¹¡£

        # tune2fs -O extents /dev/hda1

#    If the filesystem was created with 128 byte inodes, it can be
#    converted to use 256 byte for greater efficiency via:
    ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤¬ 128 ¥Ð¥¤¥È inode ¤ÇºîÀ®¤µ¤ì¤Æ¤¤¤ë¾ì¹ç¤Ï¡¢¸úΨ¤Î¤¿¤á
    256 ¥Ð¥¤¥È¤ò»ÈÍѤ¹¤ë¤è¤¦°Ê²¼¤Î¤è¤¦¤ËÊÑ´¹¤Ç¤­¤Þ¤¹¡£

        # tune2fs -I 256 /dev/hda1

#    (Note: we currently do not have tools to convert an ext4
#    filesystem back to ext3; so please do not do try this on production
#    filesystems.)
     (Ãí°Õ: ¸½ºß¤Î¤È¤³¤í ext4 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤ò ext3 ¤ËÌ᤹¥Ä¡¼¥ë¤ÏÄó¶¡
     ¤·¤Æ¤¤¤Þ¤»¤ó¡£¤³¤Î¤¿¤á¡¢¶È̳ÍøÍѤ·¤Æ¤¤¤ë¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Ç»î¤µ¤Ê¤¤¤Ç¤¯
     ¤À¤µ¤¤)

#  - Mounting:
   - ¥Þ¥¦¥ó¥È¤¹¤ë:

        # mount -t ext4 /dev/hda1 /wherever

#  - When comparing performance with other filesystems, it's always
#    important to try multiple workloads; very often a subtle change in a
#    workload parameter can completely change the ranking of which
#    filesystems do well compared to others.  When comparing versus ext3,
#    note that ext4 enables write barriers by default, while ext3 does
#    not enable write barriers by default.  So it is useful to use
#    explicitly specify whether barriers are enabled or not when via the
#    '-o barriers=[0|1]' mount option for both ext3 and ext4 filesystems
#    for a fair comparison.  When tuning ext3 for best benchmark numbers,
#    it is often worthwhile to try changing the data journaling mode; '-o
#    data=writeback,nobh' can be faster for some workloads.  (Note
#    however that running mounted with data=writeback can potentially
#    leave stale data exposed in recently written files in case of an
#    unclean shutdown, which could be a security exposure in some
#    situations.)  Configuring the filesystem with a large journal can
#    also be helpful for metadata-intensive workloads.
  - ¾¤Î¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤È¤ÎÀ­Ç½Èæ³Ó¤ÎºÝ¤Ï¡¢Ê£¿ô¤ÎÉé²Ù´Ä¶­¤Ç»î¤¹¤³¤È¤¬¾ï¤Ë
    ½ÅÍפǤ¹¡£¥ï¡¼¥¯¥í¡¼¥É¥Ñ¥é¥á¡¼¥¿¤Î¤ï¤º¤«¤ÊÊѹ¹¤¬¡¢¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Î¾
    ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤È¤ÎÈæ³Óɾ²Á¤Å¤±¤ò¤Þ¤Ã¤¿¤¯ÊѤ¨¤Æ¤·¤Þ¤¦¤³¤È¤¬ÉÑÈˤ˵¯¤³
    ¤ê¤Þ¤¹¡£ÆÃ¤Ë ext3 ¤È¤ÎÈæ³Ó¤Î¾ì¹ç¤Ï¡¢ext4 ¤¬½ñ¤­¹þ¤ß¥Ð¥ê¥¢¤òɸ½à¤ÇÍ­¸ú
    ²½¤·¤Æ¤ª¤ê¡¢ext3 ¤Ïɸ½à¤Ç¤Ï¥é¥¤¥È¥Ð¥ê¥¢¤òÍ­¸ú¤Ë¤·¤Æ¤Ï¤¤¤Ê¤¤¤³¤È¤Ëα°Õ
    ¤·¤Æ¤¯¤À¤µ¤¤¡£½¾¤Ã¤Æ¡¢¸øÊ¿¤ÊÈæ³Ó¤Î¤¿¤á¤Ë¤Ï¥é¥¤¥È¥Ð¥ê¥¢¤ÎÍ­¸ú¡¦Ìµ¸ú¤òÌÀ
    ¼¨Åª¤Ë¡¢ext3 ¤È ext4 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤È¤â '-o barriers=[0|1]' ¤ò»È¤Ã¤Æ
    »ØÄꤹ¤ë¤Î¤¬Ìò¤ËΩ¤Ä¤Ç¤·¤ç¤¦¡£ext4 ¤òºÇ¹â¤Î¥Ù¥ó¥Á¥Þ¡¼¥¯·ë²Ì¤È¤Ê¤ë¤è¤¦
    ¤Ë¥Á¥å¡¼¥Ë¥ó¥°¤¹¤ë¾ì¹ç¡¢¥Ç¡¼¥¿¥¸¥ã¡¼¥Ê¥ê¥ó¥°¥â¡¼¥É¤ÎÊѹ¹¤ò»î¤¹¤³¤È¤Ë¤Ï
    ²ÁÃͤ¬¤¢¤ê¤Þ¤¹¡£Î㤨¤Ð¡¢°ìÉô¤Î¥Ù¥ó¥Á¥Þ¡¼¥¯¤Ç¤Ï
    '-o data=writeback,nobh' ¤Ï¾¤è¤ê¹â®¤È¤Ê¤ë¤Ç¤·¤ç¤¦ (Ãí°Õ¤È¤·¤Æ¡¢
    data=writeback ¥â¡¼¥É¤Ç¥Þ¥¦¥ó¥È±¿ÍѤ·¤Æ¤¤¤ë¾ì¹ç¡¢¥¯¥ê¡¼¥ó¤Ç¤Ê¤¤¥·¥ã¥Ã
    ¥È¥À¥¦¥ó¤ÇľÁ°¤Ë½ñ¤¤¤¿¥Ç¡¼¥¿¤¬¥´¥ß¤È¤·¤Æ»Ä¤ë²ÄǽÀ­¤¬¤¢¤ë¤¿¤á¡¢¾õ¶·¤Ë¤è
    ¤Ã¤Æ¤Ï¥»¥­¥å¥ê¥Æ¥£Ì̤ǤξðÊóϳ±Ì¤Î²ÄǽÀ­¤¬¤¢¤ê¤Þ¤¹)¡£¥¸¥ã¡¼¥Ê¥ë¤òÂ礭
    ¤¯¼è¤ë¤è¤¦ÀßÄꤹ¤ë¤³¤È¤â¡¢metadata ¤ò¿ÍѤ¹¤ëÉé²Ù¤Ç¤ÏÀ­Ç½¤Î½õ¤±¤Ë¤Ê¤ê
    ¤Þ¤¹¡£
    <!-- ext3 ¤È½ñ¤«¤ì¤Æ¤¤¤ë¤Î¤Ï¤É¤¦¸«¤Æ¤â¸íµ­¤Ê¤Î¤Ç¡¢Ìõʸ¤Ç¤Ï½¤Àµ -->

#2. Features
#===========
2. µ¡Ç½
=======

#2.1 Currently available
2.1 ¸½ºß»È¤¨¤ëµ¡Ç½

#* ability to use filesystems > 16TB (e2fsprogs support not available yet)
#* extent format reduces metadata overhead (RAM, IO for access, transactions)
#* extent format more robust in face of on-disk corruption due to magics,
#* internal redundancy in tree
#* improved file allocation (multi-block alloc)
#* lift 32000 subdirectory limit imposed by i_links_count[1]
#* nsec timestamps for mtime, atime, ctime, create time
#* inode version field on disk (NFSv4, Lustre)
#* reduced e2fsck time via uninit_bg feature
#* journal checksumming for robustness, performance
#* persistent file preallocation (e.g for streaming media, databases)
#* ability to pack bitmaps and inode tables into larger virtual groups via the
#  flex_bg feature
#* large file support
#* Inode allocation using large virtual block groups via flex_bg
#* delayed allocation
#* large block (up to pagesize) support
#* efficent new ordered mode in JBD2 and ext4(avoid using buffer head to force
#  the ordering)
* 16TB Ķ¤Î¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤ÎÍøÍÑ (e2fsprogs ¤Ç¤Ï¤Þ¤À¥µ¥Ý¡¼¥È¤µ¤ì¤Æ¤¤¤Þ¤»¤ó)
* ¥á¥¿¥Ç¡¼¥¿¥ª¡¼¥Ð¥Ø¥Ã¥É (RAM, ¥¢¥¯¥»¥¹ I/O, ¥È¥é¥ó¥¶¥¯¥·¥ç¥ó) ¤ò¸º¤é¤¹¥¨¥¯
  ¥¹¥Æ¥ó¥È¥Õ¥©¡¼¥Þ¥Ã¥È
* magic ¤Ë¤è¤ë¥Ç¥£¥¹¥¯¾å¤Î¥Ç¡¼¥¿Ç˲õ¤ËÂФ·¤Æ¡¢¤è¤ê´è¶¯¤Ê¥¨¥¯¥¹¥Æ¥ó¥È¥Õ¥©¡¼
  ¥Þ¥Ã¥È
* ÌÚ¹½Â¤¤ÎÆâÉô¾éĹÀ­
* ¥Õ¥¡¥¤¥ë³ä¤êÅö¤Æ¤Î²þÁ± (Ê£¿ô¥Ö¥í¥Ã¥¯¥¢¥í¥±¡¼¥·¥ç¥ó)
* i_links_count[1] ¤Ë¤è¤ë¡¢32000 ¤Î¥µ¥Ö¥Ç¥£¥ì¥¯¥È¥ê¿ôÀ©¸Â¤ÎűÇÑ
* mtime, atime, ctime, create time(ºîÀ®»þ¹ï) ¤Ë nsec ñ°Ì¤Î¥¿¥¤¥à¥¹¥¿¥ó¥×
* ¥Ç¥£¥¹¥¯¾å¤Ç¤Î inode ¥Ð¡¼¥¸¥ç¥ó¥Õ¥£¡¼¥ë¥É (NFSv4¡¢Lustre)
* uninit_bg µ¡Ç½¤Ë¤è¤ë e2fsck »þ´Ö¤Îºï¸º
* ´è·ò¤µ¤ÈÀ­Ç½¤ò¸þ¾å¤µ¤»¤ë¤¿¤á¤Î¥¸¥ã¡¼¥Ê¥ë¥Á¥§¥Ã¥¯¥µ¥àµ¡Ç½
* »ý³¥Õ¥¡¥¤¥ë»öÁ°³ä¤êÅö¤Æ (¥¹¥È¥ê¡¼¥ß¥ó¥°¥á¥Ç¥£¥¢¤ä¥Ç¡¼¥¿¥Ù¡¼¥¹¸þ¤±)
* ¥Ó¥Ã¥È¥Þ¥Ã¥×¤È inode ¥Æ¡¼¥Ö¥ë¤ò¡¢flex_bg µ¡Ç½¤ò»È¤Ã¤ÆÂ礭¤Ê²¾ÁÛ¥°¥ë¡¼¥×¤Ë
  µÍ¤á¹þ¤àµ¡Ç½¡£
* µðÂç¥Õ¥¡¥¤¥ë¥µ¥Ý¡¼¥È
* flex_bg µ¡Ç½¤Ë¤è¤ë¡¢Â礭¤Ê²¾ÁÛ¥Ö¥í¥Ã¥¯¥°¥ë¡¼¥×¤òÍѤ¤¤Æ inode ¤ò³ä¤êÅö¤Æ¤ë
  µ¡Ç½
* ÃÙ±ä³ä¤êÅö¤Æ
* µðÂç¥Ö¥í¥Ã¥¯ (¥Ú¡¼¥¸¥µ¥¤¥º¤Þ¤Ç) ¤Î¥µ¥Ý¡¼¥È
* JBD2 ¤È ext4 ¤Ç¤Î¸úΨŪ¤Ê¿· ordered ¥â¡¼¥É (½ç½øÊݾڤΤ¿¤á¤Ë¥Ð¥Ã¥Õ¥¡¥Ø¥Ã
  ¥É¤òÍѤ¤¤ë¤Î¤òÈò¤±¤ë)

#[1] Filesystems with a block size of 1k may see a limit imposed by the
#directory hash tree having a maximum depth of two.
[1] ¥Ö¥í¥Ã¥¯¥µ¥¤¥º 1k ¤Î¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Ç¤Ï¡¢¥Ç¥£¥ì¥¯¥È¥ê¥Ï¥Ã¥·¥å¥Ä¥ê¡¼¤¬ºÇÂç
¿¼¤µ 2 ¤Ç¤¢¤ë¤³¤È¤«¤éÍè¤ëÀ©¸Â¤ËÀ©Ì󤵤ì¤Þ¤¹¡£

#2.2 Candidate features for future inclusion
2.2 ¾­ÍèÄɲøõÊä¤Ëµó¤¬¤Ã¤Æ¤¤¤ëµ¡Ç½

#* Online defrag (patches available but not well tested)
* ¥ª¥ó¥é¥¤¥ó¥Ç¥Õ¥é¥° (¥Ñ¥Ã¥Á¤Ï¤¢¤ê¤Þ¤¹¤¬¡¢½½Ê¬¤Ë¤Ï¥Æ¥¹¥È¤µ¤ì¤Æ¤¤¤Þ¤»¤ó)
#* reduced mke2fs time via lazy itable initialization in conjuction with
#  the uninit_bg feature (capability to do this is available in e2fsprogs
#  but a kernel thread to do lazy zeroing of unused inode table blocks
#  after filesystem is first mounted is required for safety)
* itable ÃÙ±ä½é´ü²½¤È uninit_bg µ¡Ç½¤òÁȤ߹ç¤ï¤»¤¿ mke2fs »þ´Ö¤Îû½Ì (¤³¤ì
  ¤ò¼Â¸½¤¹¤ëµ¡Ç½¤Ï e2fsprogs ¤Ë¤Ï´û¤ËÁȤ߹þ¤Þ¤ì¤Æ¤¤¤Þ¤¹¤¬¡¢¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à
  ¤ÎºÇ½é¤Î¥Þ¥¦¥ó¥È¸å¤Ë̤»ÈÍÑ inode ¥Æ¡¼¥Ö¥ë¥Ö¥í¥Ã¥¯¤òÃÙ±ä½é´ü²½¤¹¤ë¤¿¤á¤Î¥«
  ¡¼¥Í¥ë¥¹¥ì¥Ã¥É¤¬¡¢°ÂÁ´¤ÊÁàºî¤Î¤¿¤á¤ËɬÍפǤ¹)¡£

#There are several others under discussion, whether they all make it in is
#partly a function of how much time everyone has to work on them. Features like
#metadata checksumming have been discussed and planned for a bit but no patches
#exist yet so I'm not sure they're in the near-term roadmap.
¤³¤ì°Ê³°¤Ë¤â´ö¤Ä¤«¤Îµ¡Ç½¤¬¡¢ÁȤ߹þ¤ß¤Ë´Ø¤·¤ÆµÄÏÀÃæ¤Ç¤¹¡£µÄÏÀ¤Î·ë²Ì¤Ï¤½¤Îµ¡Ç½¤Ç
¤³¤ì¤«¤éɬÍפʺî¶È»þ´Ö (¤Î¸«Ä̤·) ¤Ë°Í¸¤¹¤ë¤Ç¤·¤ç¤¦¡£¥á¥¿¥Ç¡¼¥¿¥Á¥§¥Ã¥¯¥µ¥à¤Î
¤è¤¦¤Êµ¡Ç½¤ÏµÄÏÀ¤µ¤ì¤Æ¿¾¯¤Î·×²è¤â¤¢¤ê¤Þ¤¹¤¬¡¢¸½»þÅÀ¤Ç¤Ï¥Ñ¥Ã¥Á¤¬¤Ê¤¯¡¢¶á¤¤¾­Íè
¤Î¥í¡¼¥É¥Þ¥Ã¥×¤Ë¸½¤ï¤ì¤ë¤«¤É¤¦¤«¤ÏÄ꤫¤Ç¤Ï¤¢¤ê¤Þ¤»¤ó¡£

#The big performance win will come with mballoc, delalloc and flex_bg
#grouping of bitmaps and inode tables.  Some test results available here:
¥Ó¥Ã¥È¥Þ¥Ã¥×¤È inode ¥Æ¡¼¥Ö¥ë¤Ëmballoc¡¢delalloc ¤È¡¢flex_bg ¥°¥ë¡¼¥Ô¥ó¥°
¤òƳÆþ¤·¤¿¤³¤È¤Ë¤è¤êÂ礭¤ÊÀ­Ç½²þÁ±¤¬¼Â¸½¤µ¤ì¤Æ¤¤¤Þ¤¹¡£À­Ç½Â¬Äê·ë²Ì¤Î°ìÉô¤Ï
°Ê²¼¤Ç¸ø³«¤µ¤ì¤Æ¤¤¤Þ¤¹¡£

 - http://www.bullopensource.org/ext4/20080818-ffsb/ffsb-write-2.6.27-rc1.html
 - http://www.bullopensource.org/ext4/20080818-ffsb/ffsb-readwrite-2.6.27-rc1.html

#3. Options
#==========
3. ¥Þ¥¦¥ó¥È¥ª¥×¥·¥ç¥ó
====================

#When mounting an ext4 filesystem, the following option are accepted:
#(*) == default
ext4 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¥Þ¥¦¥ó¥È»þ¡¢°Ê²¼¤Î¥ª¥×¥·¥ç¥ó¤¬»È¤¨¤Þ¤¹¡£
(*) == ´ûÄêÃÍ

#ro                     Mount filesystem read only. Note that ext4 will
#                       replay the journal (and thus write to the
#                       partition) even when mounted "read only". The
#                       mount options "ro,noload" can be used to prevent
#                       writes to the filesystem.
ro                      ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤ò¥ê¡¼¥É¥ª¥ó¥ê¡¼¤Ç¥Þ¥¦¥ó¥È¤¹¤ë¡£ext4
                        ¤Ï¥ê¡¼¥É¥ª¥ó¥ê¡¼¤Ç¥Þ¥¦¥ó¥È¤·¤¿¾ì¹ç¤Ë¤â¥¸¥ã¡¼¥Ê¥ë¤Î¥ê
                        ¥×¥ì¥¤¤ò¹Ô¤¦ (½¾¤Ã¤Æ¥Ñ¡¼¥Æ¥£¥·¥ç¥ó¤Ë½ñ¤­¹þ¤ß¤ò¹Ô¤¦)
                        ¤³¤È¤ËÃí°Õ¤·¤Æ¤¯¤À¤µ¤¤¡£¥Þ¥¦¥ó¥È¥ª¥×¥·¥ç¥ó
                        "ro,noload" ¤ò¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Ø¤Î½ñ¤­¹þ¤ß¤òÁ˻ߤ¹
                        ¤ë¤¿¤á¤Ë»ÈÍѤ¹¤ë¤³¤È¤¬¤Ç¤­¤Þ¤¹¡£

#journal_checksum       Enable checksumming of the journal transactions.
#                       This will allow the recovery code in e2fsck and the
#                       kernel to detect corruption in the kernel.  It is a
#                       compatible change and will be ignored by older kernels.
journal_checksum        ¥¸¥ã¡¼¥Ê¥ë¥È¥é¥ó¥¶¥¯¥·¥ç¥ó»þ¤Ë¥Á¥§¥Ã¥¯¥µ¥à¤òÍ­¸ú¤Ë¤·
                        ¤Þ¤¹¡£¤³¤ì¤Ë¤è¤ê e2fsck ¤Î¥ê¥«¥Ð¥ê¥³¡¼¥É¤òÍ­¸ú¤Ë¤·¡¢
                        ¥«¡¼¥Í¥ëÆâ¤Ç¤ÎÇ˲õ¤ò¸¡½Ð¤Ç¤­¤ë¤è¤¦¤Ë¤·¤Þ¤¹¡£¤³¤ì¤Ï¸ß
                        ´¹À­¤ò»ý¤Ã¤¿Êѹ¹¤Ç¡¢½¾Íè¤Î¥«¡¼¥Í¥ë¤Ç¤Ïñ¤Ë̵»ë¤µ¤ì¤Þ
                        ¤¹¡£

#journal_async_commit   Commit block can be written to disk without waiting
#                       for descriptor blocks. If enabled older kernels cannot
#                       mount the device. This will enable 'journal_checksum'
#                       internally.
journal_async_commit    ¥Ç¥£¥¹¥¯¥ê¥×¥¿¥Ö¥í¥Ã¥¯¤Î½ñ¤­¹þ¤ß¤òÂÔ¤¿¤º¤Ë¡¢¥³¥ß¥Ã¥È
                        ¤·¤¿¥Ö¥í¥Ã¥¯¤Î¥Ç¥£¥¹¥¯¤Ø¤Î½ñ¤­¹þ¤ß¤òµö¤·¤Þ¤¹¡£Í­¸ú¤Ë
                        ¤·¤Æ¤¤¤ë¾ì¹ç¡¢½¾Íè¤Î¥«¡¼¥Í¥ë¤Ç¤Ï¥Ç¥Ð¥¤¥¹¤ò¥Þ¥¦¥ó¥È¤Ç
                        ¤­¤Þ¤»¤ó¡£¤³¤ì¤Ë¤è¤ê¡¢ÆâÉôŪ¤Ë journal_checksum ¤¬
                        Í­¸ú¤Ë¤µ¤ì¤Þ¤¹¡£

#journal=update         Update the ext4 file system's journal to the current
#                       format.
journal=update          ext4 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Î¥¸¥ã¡¼¥Ê¥ë¤ò¸½ºß¤Î·Á¼°¤Ë¥¢¥Ã
                        ¥×¥Ç¡¼¥È¤·¤Þ¤¹¡£

#journal_dev=devnum     When the external journal device's major/minor numbers
#                       have changed, this option allows the user to specify
#                       the new journal location.  The journal device is
#                       identified through its new major/minor numbers encoded
#                       in devnum.
journal_dev=devnum      ³°Éô¥¸¥ã¡¼¥Ê¥ë¥Ç¥Ð¥¤¥¹¤Î major/minor Èֹ椬ÊѲ½¤·¤¿
                        ¾ì¹ç¡¢¤³¤Î¥ª¥×¥·¥ç¥ó¤ò»È¤Ã¤Æ¿·¤·¤¤¥¸¥ã¡¼¥Ê¥ë¤Î°ÌÃÖ¤ò
                        »ØÄꤷ¤Þ¤¹¡£¥¸¥ã¡¼¥Ê¥ë¥Ç¥Ð¥¤¥¹¤Ï devnum ·Á¼°¤Ç¥¨¥ó¥³
                        ¡¼¥É¤µ¤ì¤¿ major/minor ÈÖ¹æ¤Ç»ØÄꤵ¤ì¤Þ¤¹¡£

#noload                 Don't load the journal on mounting.  Note that
#                       if the filesystem was not unmounted cleanly,
#                       skipping the journal replay will lead to the
#                       filesystem containing inconsistencies that can
#                       lead to any number of problems.
noload                  ¥Þ¥¦¥ó¥È»þ¤Ë¥¸¥ã¡¼¥Ê¥ë¤ò¥í¡¼¥É¤·¤Þ¤»¤ó¡£¤â¤·¥Õ¥¡¥¤¥ë¥·¥¹
                        ¥Æ¥à¤¬¥¯¥ê¡¼¥ó¤Ë¥¢¥ó¥Þ¥¦¥ó¥È¤µ¤ì¤Æ¤¤¤Ê¤«¤Ã¤¿¾ì¹ç¤Ë¤Ï¡¢¥¸
                        ¥ã¡¼¥Ê¥ë¥ê¥×¥ì¥¤¤òÈô¤Ð¤¹¤³¤È¤Ë¤è¤ê¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤ËÉÔÀ°
                        ¹ç¤¬È¯À¸¤¹¤ë¤Ç¤·¤ç¤¦¤·¡¢¤½¤Î·ë²ÌÍÍ¡¹¤ÊÌäÂ꤬µ¯¤­¤ë¤Ç¤·¤ç
                        ¤¦¡£

#data=journal           All data are committed into the journal prior to being
#                       written into the main file system.
data=journal            Á´¥Ç¡¼¥¿¤Ï¡¢¥á¥¤¥ó¤Î¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Ë½ñ¤­¹þ¤àÁ°¤Ë¡¢
                        ¥¸¥ã¡¼¥Ê¥ë¤Ë¥³¥ß¥Ã¥È¤µ¤ì¤Þ¤¹¡£

#data=ordered   (*)     All data are forced directly out to the main file
#                       system prior to its metadata being committed to the
#                       journal.
data=ordered    (*)     Á´¥Ç¡¼¥¿¤Ï¡¢¤½¤Î¥á¥¿¥Ç¡¼¥¿¤¬¥¸¥ã¡¼¥Ê¥ë¤Ë¥³¥ß¥Ã¥È¤µ¤ì
                        ¤ëÁ°¤Ë¡¢¥á¥¤¥ó¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤ËľÀܽÐÎϤµ¤ì¤Þ¤¹¡£

#data=writeback         Data ordering is not preserved, data may be written
#                       into the main file system after its metadata has been
#                       committed to the journal.
data=writeback          ¥Ç¡¼¥¿¤Î½ç½ø¤ÏÊݸ¤µ¤ì¤Þ¤»¤ó¡£¥Ç¡¼¥¿¤Ï¡¢¤½¤Î¥á¥¿¥Ç¡¼
                        ¥¿¤¬¥¸¥ã¡¼¥Ê¥ë¤Ë¥³¥ß¥Ã¥È¤µ¤ì¤¿¤¢¤È¤Ë¡¢¥á¥¤¥ó¥Õ¥¡¥¤¥ë
                        ¥·¥¹¥Æ¥à¤Ë½ñ¤­¹þ¤Þ¤ì¤ë¤«¤â¤·¤ì¤Þ¤»¤ó¡£

#commit=nrsec   (*)     Ext4 can be told to sync all its data and metadata
#                       every 'nrsec' seconds. The default value is 5 seconds.
#                       This means that if you lose your power, you will lose
#                       as much as the latest 5 seconds of work (your
#                       filesystem will not be damaged though, thanks to the
#                       journaling).  This default value (or any low value)
#                       will hurt performance, but it's good for data-safety.
#                       Setting it to 0 will have the same effect as leaving
#                       it at the default (5 seconds).
#                       Setting it to very large values will improve
#                       performance.
commit=nrsec    (*)     Ext4 ¤Ï¥Ç¡¼¥¿¤È¥á¥¿¥Ç¡¼¥¿¤ò¡¢'nrsec' ÉÃËè¤ËƱ´ü¤Ç¤­¤Þ
                        ¤¹¡£¥Ç¥Õ¥©¥ë¥È¤Ï¡¢5 ÉäǤ¹¡£¤³¤ì¤Ï¡¢ÅŸ»¤¬ÀÚ¤ì¤Æ¤·¤Þ¤Ã
                        ¤¿»þ¡¢ºÇ¸å¤Î 5 Éô֤κî¶ÈÆâÍƤ¬¼º¤ï¤ì¤Æ¤·¤Þ¤¦¤³¤È¤ò°Õ
                        Ì£¤·¤Þ¤¹ (¤·¤«¤·¡¢¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Ï¡¢¥¸¥ã¡¼¥Ê¥ê¥ó¥°¤Î
                        ¤ª¤«¤²¤ÇÇ˲õ¤µ¤ì¤Ê¤¤¤Ç¤·¤ç¤¦)¡£
                        ¤³¤Î¥Ç¥Õ¥©¥ë¥ÈÃÍ (¤Þ¤¿¤Ï¡¢¤è¤ê¾®¤µ¤¤ÃÍ) ¤Ï¡¢À­Ç½¤Ë±Æ¶Á
                        ¤òÍ¿¤¨¤Þ¤¹¤¬¡¢¥Ç¡¼¥¿¤Î°ÂÁ´À­¤Ï¸þ¾å¤·¤Þ¤¹¡£0 ¤Ë¤·¤¿¾ì
                        ¹ç¤Ï¡¢¥Ç¥Õ¥©¥ë¥È¤Î 5 Éäˤ·¤¿¤Î¤ÈƱ¤¸¸ú²Ì¤È¤Ê¤ê¤Þ¤¹¡£
                        ¤È¤Æ¤âÂ礭¤ÊÃͤˤ¹¤ë¤È¥Ñ¥Õ¥©¡¼¥Þ¥ó¥¹¤¬¸þ¾å¤·¤Þ¤¹¡£

#barrier=<0|1(*)>       This enables/disables the use of write barriers in
#barrier(*)             the jbd code.  barrier=0 disables, barrier=1 enables.
#nobarrier              This also requires an IO stack which can support
#                       barriers, and if jbd gets an error on a barrier
#                       write, it will disable again with a warning.
#                       Write barriers enforce proper on-disk ordering
#                       of journal commits, making volatile disk write caches
#                       safe to use, at some performance penalty.  If
#                       your disks are battery-backed in one way or another,
#                       disabling barriers may safely improve performance.
#                       The mount options "barrier" and "nobarrier" can
#                       also be used to enable or disable barriers, for
#                       consistency with other ext4 mount options.
barrier=<0|1(*)>        jbd ¥³¡¼¥É¤Ç¤Î¥é¥¤¥È¥Ð¥ê¥¢¤ÎÍøÍѤòÍ­¸ú/̵¸ú¤Ë¤·¤Þ¤¹¡£
barrier(*)              barrier=0 ¤Ï̵¸ú²½¤·¡¢barrier=1 ¤ÏÍ­¸ú¤Ë¤·¤Þ¤¹¡£¤³
nobarrier               ¤Î¥é¥¤¥È¥Ð¥ê¥¢¤ÎÍ­¸ú²½¤Î¤¿¤á¤Ë¤Ï¥Ð¥ê¥¢¤òÍ­¸ú²½¤·¤¿
                        IO ¥¹¥¿¥Ã¥¯¤¬É¬Íפǡ¢¤µ¤é¤Ë jbd ¤¬¥Ð¥ê¥¢¥é¥¤¥È»þ¤Ë
                        ¥¨¥é¡¼¤ò¼õ¤±¤¿¤Ê¤é¤Ð·Ù¹ð¤È¤È¤â¤Ë̵¸ú¤Ë¤â¤É¤ê¤Þ¤¹¡£¥é
                        ¥¤¥È¥Ð¥ê¥¢¤Ï¿¾¯¤ÎÀ­Ç½¤Îµ¾À·¤Ë¤è¤ê¡¢Å¬Àڤʥǥ£¥¹¥¯¾å
                        ¤Î¥¸¥ã¡¼¥Ê¥ë¥³¥ß¥Ã¥È¤Î½ç½ø¤ò¼Â¸½¤·¡¢´øȯÀ­¤Î¥Ç¥£¥¹¥¯
                        ¥é¥¤¥È¥­¥ã¥Ã¥·¥å¤ò°ÂÁ´¤Ë»ÈÍѤǤ­¤ë¤è¤¦¤Ë¤·¤Þ¤¹¡£
                        ¤â¤·»ÈÍѤ·¤Æ¤¤¤ë¥Ç¥£¥¹¥¯¥³¥ó¥È¥í¡¼¥é¤¬ÅÅÃӤǥХå¯
                        ¥¢¥Ã¥×¤µ¤ì¤Æ¤¤¤ë¤Ê¤É¤Î¾ì¹ç¤Ë¤Ï¡¢¥Ð¥ê¥¢¤ò̵¸ú²½¤¹¤ë
                        ¤³¤È¤Ë¤è¤ê°ÂÁ´¤ËÀ­Ç½¤ò¸þ¾å¤Ç¤­¤Þ¤¹¡£
                        ¥Þ¥¦¥ó¥È¥ª¥×¥·¥ç¥ó "barrier" ¤È "nobarrier" ¤ò¥Ð¥ê
                        ¥¢¤ÎÍ­¸ú̵¸ú¤ò»ØÄꤹ¤ë¤¿¤á¤ËÍѤ¤¤ë¤³¤È¤¬¤Ç¤­¤Þ¤¹¡£¤³
                        ¤Î¥ª¥×¥·¥ç¥ó¤Ï¡¢Â¾¤Î ext4 ¥Þ¥¦¥ó¥È¥ª¥×¥·¥ç¥ó¤È¤Î°ì´Ó
                        À­°Ý»ý¤Î¤¿¤áÄ󶡤µ¤ì¤Æ¤¤¤Þ¤¹¡£

#inode_readahead=n      This tuning parameter controls the maximum
#                       number of inode table blocks that ext4's inode
#                       table readahead algorithm will pre-read into
#                       the buffer cache.  The default value is 32 blocks.
inode_readahead=n       ¤³¤Î¥Á¥å¡¼¥Ë¥ó¥°¥Ñ¥é¥á¡¼¥¿¤Ï¡¢ext4 inode ¥Æ¡¼¥Ö¥ëÀèÆÉ
                        ¤ß¥¢¥ë¥´¥ê¥º¥à¤¬¥Ð¥Ã¥Õ¥¡¥­¥ã¥Ã¥·¥å¤ËÀèÆɤߤ¹¤ë¡¢inode
                        ¥Æ¡¼¥Ö¥ë¥Ö¥í¥Ã¥¯¤Î¿ô¤ÎºÇÂçÃͤòÀ©¸æ¤·¤Þ¤¹¡£´ûÄêÃÍ¤Ï 32
                        ¥Ö¥í¥Ã¥¯¤Ç¤¹¡£

#orlov          (*)     This enables the new Orlov block allocator. It is
#                       enabled by default.
orlov           (*)     ¿·¤·¤¤¡¢Orlov ¥Ö¥í¥Ã¥¯¥¢¥í¥±¡¼¥¿¤òÍ­¸ú¤Ë¤·¤Þ¤¹¡£¥Ç¥Õ
                        ¥©¥ë¥È¤ÇÍ­¸ú¤Ç¤¹¡£

#oldalloc               This disables the Orlov block allocator and enables
#                       the old block allocator.  Orlov should have better
#                       performance - we'd like to get some feedback if it's
#                       the contrary for you.
oldalloc                Orlov ¥Ö¥í¥Ã¥¯¥¢¥í¥±¡¼¥¿¤ò̵¸ú¤Ë¤·¤Æ¡¢¸Å¤¤¥Ö¥í¥Ã¥¯¥¢
                        ¥í¥±¡¼¥¿¤òÍ­¸ú¤Ë¤·¤Þ¤¹¡£Orlov ¤ÎÊý¤¬À­Ç½¤¬Îɤ¤¤Ï¤º¤Ç¤¹¤¬¡¢
                        ¤â¤·¡¢µÕ¸ú²Ì¤Ê¤é¡¢ÃΤ餻¤Æ¤¯¤À¤µ¤¤¡£

#user_xattr             Enables Extended User Attributes.  Additionally, you
#                       need to have extended attribute support enabled in the
#                       kernel configuration (CONFIG_EXT4_FS_XATTR).  See the
#                       attr(5) manual page and http://acl.bestbits.at/ to
#                       learn more about extended attributes.
user_xattr              POSIX ³Èĥ°À­¤òÍ­¸ú¤Ë¤·¤Þ¤¹¡£Í­¸ú¤Ë¤¹¤ë¤Ë¤Ï¡¢¤µ¤é¤Ë¥«¡¼
                        ¥Í¥ëÀßÄê¤Ç³Èĥ°À­¤Î¥µ¥Ý¡¼¥È (CONFIG_EXT4_FS_XATTR) ¤ò
                        ÁȤ߹þ¤àɬÍפ¬¤¢¤ê¤Þ¤¹¡£
                        POSIX ³Èĥ°À­¤Î¾ÜºÙ¤ò³Ø¤Ö¤Ë¤Ï¡¢attr(5) ¤Î¥Þ¥Ë¥å¥¢¥ë¥Ú¡¼
                        ¥¸¤È http://acl.bestbits.at ¤ò¸«¤Æ¤¯¤À¤µ¤¤¡£

#nouser_xattr           Disables Extended User Attributes.
nouser_xattr            POSIX ³Èĥ°À­ ¤ò̵¸ú¤Ë¤·¤Þ¤¹¡£

#acl                    Enables POSIX Access Control Lists support.
#                       Additionally, you need to have ACL support enabled in
#                       the kernel configuration (CONFIG_EXT4_FS_POSIX_ACL).
#                       See the acl(5) manual page and http://acl.bestbits.at/
#                       for more information.
acl                     POSIX ¥¢¥¯¥»¥¹À©¸æ¥ê¥¹¥È (POSIX ACL) ¥µ¥Ý¡¼¥È¤òÍ­¸ú¤Ë
                        ¤·¤Þ¤¹¡£Í­¸ú¤Ë¤¹¤ë¤Ë¤Ï¡¢¤µ¤é¤Ë¥«¡¼¥Í¥ëÀßÄê¤Ç ACL ¤Î¥µ¥Ý
                        ¡¼¥È (CONFIG_EXT4_FS_POSIX_ACL) ¤òÁȤ߹þ¤àɬÍפ¬¤¢¤ê
                        ¤Þ¤¹¡£
                        ACL ¤Î¾ÜºÙ¤Ï¡¢acl(5) ¤Î¥Þ¥Ë¥å¥¢¥ë¥Ú¡¼¥¸¤È
                        http://acl.bestbits.at ¤ò¸«¤Æ¤¯¤À¤µ¤¤¡£

#noacl                  This option disables POSIX Access Control List
#                       support.
noacl                   POSIX ¥¢¥¯¥»¥¹À©¸æ¥ê¥¹¥È(POSIX ACL) ¤ò̵¸ú¤Ë¤·¤Þ¤¹¡£

reservation

noreservation

#bsddf          (*)     Make 'df' act like BSD.
#minixdf                        Make 'df' act like Minix.
bsddf           (*)     'df' ¤ÎÆ°ºî¤ò BSD ¤ÈƱÍͤˤ·¤Þ¤¹¡£
minixdf                 'df' ¤ÎÆ°ºî¤ò Minix ¤ÈƱÍͤˤ·¤Þ¤¹¡£

#debug                  Extra debugging information is sent to syslog.
debug                   ÄɲåǥХå°¾ðÊó¤ò syslog ¤ËÁ÷¤ê¤Þ¤¹¡£

#abort                  Simulate the effects of calling ext4_abort() for
#                       debugging purposes.  This is normally used while
#                       remounting a filesystem which is already mounted.
abort                   ¥Ç¥Ð¥Ã¥°¤Î¤¿¤á ext4_abort() ¸Æ¤Ó½Ð¤·¤Î¸ú²Ì¤ò¥·¥ß
                        ¥å¥ì¡¼¥È¤·¤Þ¤¹¡£¤³¤ì¤ÏÄ̾ï¤Ï¡¢´û¤Ë¥Þ¥¦¥ó¥È¤µ¤ì¤Æ¤¤
                        ¤ë¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤òºÆ¥Þ¥¦¥ó¥È¤·¤è¤¦¤È¤¹¤ë¤Ð¤¢¤¤¤Ë
                        ÍøÍÑ (ȯÀ¸) ¤µ¤ì¤Þ¤¹¡£

#errors=remount-ro      Remount the filesystem read-only on an error.
#errors=continue                Keep going on a filesystem error.
#errors=panic           Panic and halt the machine if an error occurs.
#                        (These mount options override the errors behavior
#                        specified in the superblock, which can be configured
#                        using tune2fs)
errors=remount-ro(*)    ¥¨¥é¡¼»þ¡¢Æɤ߹þ¤ßÀìÍѤǥե¡¥¤¥ë¥·¥¹¥Æ¥à¤òºÆ¥Þ¥¦¥ó¥È
                        ¤·¤Þ¤¹¡£
errors=continue         ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¥¨¥é¡¼¤¬È¯À¸¤·¤Æ¤â·Ñ³¤·¤Þ¤¹¡£
errors=panic            ¥¨¥é¡¼¤¬È¯À¸¤·¤¿¤é¡¢PANIC ¤·¤Æ¡¢¥Þ¥·¥ó¤òÄä»ß¤·¤Þ¤¹
                        (¤³¤ì¤é¤Î¥ª¥×¥·¥ç¥ó¤Ï¡¢tune2fs ¤ÇÀßÄê»þ¤Ë»ØÄꤷ¤¿¡¢
                        superblock ¤Ç»ØÄꤷ¤¿¥¨¥é¡¼»þ¤ÎµóÆ°»ØÄê¤ò¾å½ñ¤­¤·¤Þ¤¹)¡£

#data_err=ignore(*)     Just print an error message if an error occurs
#                       in a file data buffer in ordered mode.
#data_err=abort         Abort the journal if an error occurs in a file
#                       data buffer in ordered mode.
data_err=ignore(*)      ¥ª¡¼¥À¡¼¥É¥â¡¼¥É¤Ç¥Õ¥¡¥¤¥ë¥Ç¡¼¥¿¥Ð¥Ã¥Õ¥¡¤Ç¥¨¥é¡¼¤¬È¯À¸¤·
                        ¤¿¾ì¹ç¡¢Ã±¤Ë¥¨¥é¡¼¥á¥Ã¥»¡¼¥¸¤ò½ÐÎϤ¹¤ë¤À¤±¤Ç¤¹¡£
data_err=abort          ¥ª¡¼¥À¡¼¥É¥â¡¼¥É¤Ç¥Õ¥¡¥¤¥ë¥Ç¡¼¥¿¥Ð¥Ã¥Õ¥¡¤Ç¥¨¥é¡¼¤¬È¯À¸¤·
                        ¤¿¾ì¹ç¡¢¥¸¥ã¡¼¥Ê¥ë¤ò°Û¾ï½ªÎ»¤·¤Þ¤¹¡£

#grpid                  Give objects the same group ID as their creator.
#bsdgroups
grpid                   ¥ª¥Ö¥¸¥§¥¯¥È¤ÎºîÀ®»þ¤Ë¡¢ºîÀ®Àè¥Ç¥£¥ì¥¯¥È¥ê¤ÈƱ¤¸¥°¥ë¡¼¥×
bsdgroups               ID ¤òÍ¿¤¨¤Þ¤¹¡£

#nogrpid        (*)     New objects have the group ID of their creator.
#sysvgroups
nogrpid         (*)     ¥ª¥Ö¥¸¥§¥¯¥È¤ÎºîÀ®»þ¤Ë¡¢ºîÀ®Àè¥Ç¥£¥ì¥¯¥È¥ê¤Ë setgid ¥Ó
sysvgroups              ¥Ã¥È¤¬¥»¥Ã¥È¤µ¤ì¤Æ¤¤¤Ê¤¤¾ì¹ç¡¢ºîÀ®¥×¥í¥»¥¹¤ÈƱ¤¸¥°¥ë¡¼¥×
                        ID ¤òÍ¿¤¨¤Þ¤¹¡£ºîÀ®Àè¥Ç¥£¥ì¥¯¥È¥ê¤Ë setgid ¥Ó¥Ã¥È¤¬¥»¥Ã
                        ¥È¤µ¤ì¤Æ¤¤¤¿¾ì¹ç¤Ë¤Ï¡¢ºîÀ®Àè¥Ç¥£¥ì¥¯¥È¥ê¤Î¥°¥ë¡¼¥× ID ¤È
                        ºîÀ®¤µ¤ì¤¿¤Î¤¬¥Ç¥£¥ì¥¯¥È¥ê¤Ç¤¢¤Ã¤¿¾ì¹ç¤Ë¤Ï setgid ¥Ó¥Ã¥È
                        ¤¬°ú¤­·Ñ¤¬¤ì¤Þ¤¹¡£

#resgid=n               The group ID which may use the reserved blocks.
resgid=n                ͽÌó¥Ö¥í¥Ã¥¯¤ò»ÈÍѤ¹¤ë¥°¥ë¡¼¥× ID ¤Ç¤¹¡£

#resuid=n               The user ID which may use the reserved blocks.
resuid=n                ͽÌó¥Ö¥í¥Ã¥¯¤ò»ÈÍѤ¹¤ë¥æ¡¼¥¶ ID ¤Ç¤¹¡£

#sb=n                   Use alternate superblock at this location.
sb=n                    ¤³¤Î°ÌÃÖ¤ÎÂåÂØ¥¹¡¼¥Ñ¡¼¥Ö¥í¥Ã¥¯¤ò»È¤¤¤Þ¤¹¡£

quota
noquota
grpquota
usrquota

#bh             (*)     ext4 associates buffer heads to data pages to
#nobh                   (a) cache disk block mapping information
#                       (b) link pages into transaction to provide
#                           ordering guarantees.
#                       "bh" option forces use of buffer heads.
#                       "nobh" option tries to avoid associating buffer
#                       heads (supported only for "writeback" mode).
bh              (*)     ext4 ¤Ï¥Ð¥Ã¥Õ¥¡ÀèƬ¤ò°Ê²¼¤Î¾ðÊó¤Ë´ØÏ¢¤Å¤±¤Þ¤¹¡£
nobh                    (a) ¥­¥ã¥Ã¥·¥å¥Ç¥£¥¹¥¯¥Ö¥í¥Ã¥¯¥Þ¥Ã¥×¾ðÊó
                        (b) ½ç½øÊݾڤΤ¿¤á¤Î¥È¥é¥ó¥¶¥¯¥·¥ç¥óÆâ¤Î¥ê¥ó¥¯¥Ú¡¼¥¸
                        bh ¥ª¥×¥·¥ç¥ó¤Ç¤Ï¥Ð¥Ã¥Õ¥¡¥Ø¥Ã¥É¤ÎÍøÍѤò¶¯À©¤·¡¢nobh
                        ¥ª¥×¥·¥ç¥ó¤Ç¤Ï¥Ð¥Ã¥Õ¥¡ÀèƬ¤È¤Î´ØÏ¢¤Å¤±¤òÈò¤±¤Þ¤¹
                        (writeback ¥â¡¼¥É¤Ç¤Î¤ß¥µ¥Ý¡¼¥È¤µ¤ì¤Þ¤¹)¡£

#stripe=n               Number of filesystem blocks that mballoc will try
#                       to use for allocation size and alignment. For RAID5/6
#                       systems this should be the number of data
#                       disks *  RAID chunk size in file system blocks.
#delalloc       (*)     Deferring block allocation until write-out time.
#nodelalloc             Disable delayed allocation. Blocks are allocation
#                       when data is copied from user to page cache.
stripe=n                mballoc ¤¬¥¢¥í¥±¡¼¥·¥ç¥óñ°Ì¤È¥¢¥é¥¤¥ó¤Ë»ÈÍѤ·¤è¤¦¤È
                        ¤¹¤ë¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¥Ö¥í¥Ã¥¯¿ô¤Ç¤¹¡£RAID5/6 ¤Ç¤Ï¡¢¤³
                        ¤ÎÃͤϥǡ¼¥¿¥Ç¥£¥¹¥¯¿ô¤È¡¢¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¥Ö¥í¥Ã¥¯¤Î
                        RAID ¥Á¥ã¥ó¥¯¥µ¥¤¥º¤È¤ÎÀѤˤ¹¤Ù¤­¤Ç¤¹¡£
delalloc        (*)     ½ñ¤­¹þ¤ß»þ¤Þ¤Ç¥Ö¥í¥Ã¥¯³ä¤êÅö¤Æ¤òÃٱ䤵¤»¤Þ¤¹¡£
nodelalloc              ÃÙ±ä³ä¤êÅö¤Æ¤ò̵¸ú¤Ë¤·¤Þ¤¹¡£¥Ç¡¼¥¿¤¬¥æ¡¼¥¶¤«¤é¥Ú¡¼¥¸
                        ¥­¥ã¥Ã¥·¥å¤Ë½ñ¤­¹þ¤Þ¤ì¤¿»þÅÀ¤Ç¥Ö¥í¥Ã¥¯³ä¤êÅö¤Æ¤¬¹Ô¤Ê
                        ¤ï¤ì¤Þ¤¹¡£

#max_batch_time=usec    Maximum amount of time ext4 should wait for
#                       additional filesystem operations to be batch
#                       together with a synchronous write operation.
#                       Since a synchronous write operation is going to
#                       force a commit and then a wait for the I/O
#                       complete, it doesn't cost much, and can be a
#                       huge throughput win, we wait for a small amount
#                       of time to see if any other transactions can
#                       piggyback on the synchronous write.   The
#                       algorithm used is designed to automatically tune
#                       for the speed of the disk, by measuring the
#                       amount of time (on average) that it takes to
#                       finish committing a transaction.  Call this time
#                       the "commit time".  If the time that the
#                       transaction has been running is less than the
#                       commit time, ext4 will try sleeping for the
#                       commit time to see if other operations will join
#                       the transaction.   The commit time is capped by
#                       the max_batch_time, which defaults to 15000us
#                       (15ms).   This optimization can be turned off
#                       entirely by setting max_batch_time to 0.
max_batch_time=usec     ext4 ¤ÎƱ´ü½ñ¤­¹þ¤ßÁàºî»þ¤Ë¡¢Ê̤Υե¡¥¤¥ëÁàºî¤ò¹ç¤ï¤»¤Æ
                        ¥Ð¥Ã¥Á¤¹¤ë¤¿¤á¤ËÂԤĻþ´Ö¤ÎºÇÂçÃͤò»ØÄꤷ¤Þ¤¹¡£Æ±´ü½ñ¤­
                        ¹þ¤ß½èÍý¤Ï¶¯À©Åª¤Ê¥³¥ß¥Ã¥È¤ò¹Ô¤¤¡¢¤½¤Î¸å I/O ½èÍý¤Î´°Î»
                        ¤òÂԤĤ¿¤á¡¢Æ±´ü½ñ¤­¹þ¤ß¤È°ì½ï¤Ë¤Ç¤­¤ë¾¤Î¥È¥é¥ó¥¶¥¯¥·
                        ¥ç¥ó¤Î̵ͭ¤òû»þ´ÖÂԤĤ³¤È¤Ï¡¢¥³¥¹¥È¤¬¾®¤µ¤¯¥¹¥ë¡¼¥×¥Ã
                        ¥ÈÌ̤ÇÂ礭¤Ê²þÁ±¤Ë¤Ê¤ê¤Þ¤¹¡£¤³¤³¤Ç»È¤ï¤ì¤Æ¤¤¤ë¥¢¥ë¥´¥ê
                        ¥º¥à¤Ï¡¢¥Ç¥£¥¹¥¯¤Î¥È¥é¥ó¥¶¥¯¥·¥ç¥ó¤Î¥³¥ß¥Ã¥È´°Î»¤ËÍפ¹
                        ¤ë»þ´Ö (Ê¿¶Ñ»þ´Ö) ¤ò¬Äꤹ¤ë¤³¤È¤Ë¤è¤ê¡¢¥Ç¥£¥¹¥¯Â®ÅÙ¤Ë
                        ºÇŬ²½¤¹¤ë¤è¤¦À߷פµ¤ì¤¿¤â¤Î¤Ç¤¹¡£¤³¤³¤Ç¾åµ­¤Î¡Ö¥³¥ß¥Ã
                        ¥È´°Î»¤ËÍפ¹¤ë»þ´Ö¡×¤ò ¡ÉCommit time" ¤È¸Æ¤Ö¤³¤È¤Ë¤·¤Þ
                        ¤¹¡£¤â¤·¡¢¥È¥é¥ó¥¶¥¯¥·¥ç¥ó¤ò¼Â¹Ô¤·¤Æ¤¤¤ë»þ´Ö¤¬ Commit
                        time ¤è¤ê¾®¤µ¤¤¤Ê¤é¤Ð¡¢ext4 ¤Ï Commit time ¤À¤±¥¹¥ê¡¼
                        ¥×¤·¤Æ¾¤Î½èÍý¤¬¥È¥é¥ó¥¶¥¯¥·¥ç¥ó¤Ë¹çή¤Ç¤­¤ë¤«¤É¤¦¤«¤ò
                        Ä´¤Ù¤Þ¤¹¡£¤³¤Î Commit time ¤Ï max_batch_time ¤Ë¤è¤ê
                        ¾å¸Â¤¬»ØÄꤵ¤ì¤Þ¤¹¡£max_batch_time ¤Îɸ½àÃͤÏ
                        15000us (15ms) ¤Ç¤¹¡£max_batch_time ¤ò 0 ¤È»ØÄꤹ¤ë
                        ¤³¤È¤Ç¡¢¤³¤ÎºÇŬ²½¤ò´°Á´¤Ë̵¸ú²½¤Ç¤­¤Þ¤¹¡£

#min_batch_time=usec    This parameter sets the commit time (as
#                       described above) to be at least min_batch_time.
#                       It defaults to zero microseconds.  Increasing
#                       this parameter may improve the throughput of
#                       multi-threaded, synchronous workloads on very
#                       fast disks, at the cost of increasing latency.
min_batch_time=usec     ¤³¤Î¥Ñ¥é¥á¡¼¥¿¤Ï commit time (¾åµ­»²¾È) ¤¬¡¢¾¯¤Ê¤¯¤È¤â
                        min_batch_time °Ê¾å¤Ç¤¢¤ë¤³¤È¤ò»ØÄꤷ¤Þ¤¹¡£É¸½àÃÍ¤Ï 0
                        ms ¤Ç¤¹¡£¤³¤Î¥Ñ¥é¥á¡¼¥¿¤òÁý¤ä¤·¤¿¾ì¹ç¡¢¥Þ¥ë¥Á¥¹¥ì¥Ã¥É¤Ç
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#journal_ioprio=prio    The I/O priority (from 0 to 7, where 0 is the
#                       highest priorty) which should be used for I/O
#                       operations submitted by kjournald2 during a
#                       commit operation.  This defaults to 3, which is
#                       a slightly higher priority than the default I/O
#                       priority.
journal_ioprio=prio     kjournald2 ¤¬¡¢¥³¥ß¥Ã¥È½èÍýÃæ¤Ëȯ¹Ô¤¹¤ë I/O ½èÍý¤ÇÍѤ¤
                        ¤ë I/O ¥×¥é¥¤¥ª¥ê¥Æ¥£ (0 ¤«¤é 7 ¤Ç¡¢0 ¤¬ºÇ¹â¤Î¥×¥é¥¤¥ª
                        ¥ê¥Æ¥£¤Ç¤¹) ¤ò»ØÄꤷ¤Þ¤¹¡£É¸½àÃÍ¤Ï 3 ¤Ç¡¢¤³¤ì¤ÏÄ̾ï¤Î
                        I/O ¥×¥é¥¤¥ª¥ê¥Æ¥£¤è¤ê¾¯¤·¹â¤¯¤Ê¤Ã¤Æ¤¤¤Þ¤¹¡£

#auto_da_alloc(*)       Many broken applications don't use fsync() when
#noauto_da_alloc                replacing existing files via patterns such as
#                       fd = open("foo.new")/write(fd,..)/close(fd)/
#                       rename("foo.new", "foo"), or worse yet,
#                       fd = open("foo", O_TRUNC)/write(fd,..)/close(fd).
#                       If auto_da_alloc is enabled, ext4 will detect
#                       the replace-via-rename and replace-via-truncate
#                       patterns and force that any delayed allocation
#                       blocks are allocated such that at the next
#                       journal commit, in the default data=ordered
#                       mode, the data blocks of the new file are forced
#                       to disk before the rename() operation is
#                       committed.  This provides roughly the same level
#                       of guarantees as ext3, and avoids the
#                       "zero-length" problem that can happen when a
#                       system crashes before the delayed allocation
#                       blocks are forced to disk.
auto_da_alloc(*)        ¿¤¯¤Î²õ¤ì¤¿¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤Ï¡¢fd = open("foo.new")/
noauto_da_alloc         write(fd,..)/close(fd)/rename("foo.new", "foo") ¤Ê
                        ¤É¤Î¥Ñ¥¿¡¼¥ó¡¢¤¢¤ë¤¤¤Ï¤½¤ì¤è¤ê¼Ù°­¤Ê
                        fd = open("foo", O_TRUNC)/write(fd,..)/close(fd)
                        ¥Ñ¥¿¡¼¥ó¤Ç¡¢fsync() ¤ò»È¤ï¤Ê¤¤¤Ç´û¸¤Î¥Õ¥¡¥¤¥ë¤òÆþ¤ì
                        Âؤ¨¤Þ¤¹¡£auto_da_alloc ¤¬Í­¸ú¤Ê¾ì¹ç¡¢ext4 ¤Ï¤³¤Î¥ê
                        ¥Í¡¼¥à¤Ë¤è¤ë¥Õ¥¡¥¤¥ë¤ÎÆþ¤ìÂؤ¨¤È truncate ¤Ë¤è¤ë¥Õ¥¡
                        ¥¤¥ë¤ÎÆþ¤ìÂؤ¨¤Î¥Ñ¥¿¡¼¥ó¤ò¸¡ÃΤ·¡¢É¸½à¤Î¥Ç¡¼¥¿¥ª¡¼¥À¡¼
                        ¥É¥â¡¼¥É¤Î¾ì¹ç¤Ë¡¢¥ê¥Í¡¼¥à½èÍý¤¬¥³¥ß¥Ã¥È¤µ¤ì¤ëÁ°¤Ë¿·µ¬
                        ¥Õ¥¡¥¤¥ë¤Î¥Ç¡¼¥¿¥Ö¥í¥Ã¥¯¤¬¥Ç¥£¥¹¥¯¤Ë½ñ¤­¹þ¤Þ¤ì¤ë¤è¤¦¡¢
                        ÃÙ±ä³ä¤êÅö¤Æ¤µ¤ì¤¿¥Ö¥í¥Ã¥¯¤ò¼¡¤Î¥¸¥ã¡¼¥Ê¥ë¥³¥ß¥Ã¥È»þ¤Ë
                        ¶¯À©Åª¤Ë³ä¤êÅö¤Æ¤Þ¤¹¡£¤³¤Î½èÍý¤Ç¤Û¤Ü ext3 ¤ÈƱÄøÅÙ¤ÎÊÝ
                        ¾Ú¤¬¤Ç¤­¡¢ÃÙ±ä³ä¤êÅö¤Æ¤µ¤ì¤¿¥Ö¥í¥Ã¥¯¤¬¥Ç¥£¥¹¥¯¤Ë½ñ¤«¤ì
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                        ÌäÂê¤ò (ƱÄøÅÙ¤Ë) ²óÈò¤Ç¤­¤Þ¤¹¡£

#Data Mode
#=========
¥Ç¡¼¥¿¥â¡¼¥É
===========
#There are 3 different data modes:
3 ¤Ä¤Î°Û¤Ê¤ë¥Ç¡¼¥¿¥â¡¼¥É¤òÄ󶡤·¤Æ¤¤¤Þ¤¹¡£

#* writeback mode
#In data=writeback mode, ext4 does not journal data at all.  This mode provides
#a similar level of journaling as that of XFS, JFS, and ReiserFS in its default
#mode - metadata journaling.  A crash+recovery can cause incorrect data to
#appear in files which were written shortly before the crash.  This mode will
#typically provide the best ext4 performance.
* ¥é¥¤¥È¥Ð¥Ã¥¯¥â¡¼¥É
data=writeback ¥â¡¼¥É¤Î¤È¤­¡¢ext4 ¤Ï¥Ç¡¼¥¿¤òÁ´¤¯¥¸¥ã¡¼¥Ê¥ë¤·¤Þ¤»¤ó¡£
¤³¤ì¤Ï¡¢XFS, JFS, ReiserFS ¤Î¥Ç¥Õ¥©¥ë¥È¥â¡¼¥É (¥á¥¿¥Ç¡¼¥¿¥¸¥ã¡¼¥Ê¥ê¥ó¥°) ¤È
Ʊ¥ì¥Ù¥ë¤Î¥¸¥ã¡¼¥Ê¥ê¥ó¥°¤òÄ󶡤·¤Þ¤¹¡£
¥¯¥é¥Ã¥·¥å + ¥ê¥«¥Ð¥ê ¤Ç¡¢¥¯¥é¥Ã¥·¥åľÁ°¤Ë½ñ¤­¹þ¤Þ¤ì¤¿¥Õ¥¡¥¤¥ëÆâ¤ËÉÔÀµ¥Ç¡¼¥¿
¤¬¸½¤ì¤ë¤«¤â¤·¤ì¤Þ¤»¤ó¡£Ä̾盧¤Î¥â¡¼¥É¤ÏºÇ¹â¤Î ext4 ¥Ñ¥Õ¥©¡¼¥Þ¥ó¥¹¤¬ÆÀ¤é¤ì¤Þ
¤¹¡£

#* ordered mode
#In data=ordered mode, ext4 only officially journals metadata, but it logically
#groups metadata information related to data changes with the data blocks into a
#single unit called a transaction.  When it's time to write the new metadata
#out to disk, the associated data blocks are written first.  In general,
#this mode performs slightly slower than writeback but significantly faster than
journal mode.
* ¥ª¡¼¥À¡¼¥É¥â¡¼¥É
data=ordered ¥â¡¼¥É¤Î¤È¤­¡¢ext4 ¤Ï¸ø¼°¤Ë¤Ï¥á¥¿¥Ç¡¼¥¿¤Î¤ß¤ò¥¸¥ã¡¼¥Ê¥ë¤·¤Þ¤¹
¤¬¡¢¤³¤ÎºÝ¤Ë¥á¥¿¥Ç¡¼¥¿¤È¥Ç¡¼¥¿¥Ö¥í¥Ã¥¯¤Ï¥È¥é¥ó¥¶¥¯¥·¥ç¥ó¤È¸Æ¤Ð¤ì¤ë 1 ¤Ä¤Îñ
°Ì¤Ë¡¢ÏÀÍýŪ¤Ë¤Þ¤È¤á¤é¤ì¤Æ¤¤¤Þ¤¹¡£¥Ç¥£¥¹¥¯¤Ë¿·¤·¤¤¥á¥¿¥Ç¡¼¥¿¤ò½ñ¤­¹þ¤à»þ¤¬
¤­¤¿¤é¡¢´ØÏ¢¥Ç¡¼¥¿¥Ö¥í¥Ã¥¯¤¬Àè¤Ë½ñ¤­¹þ¤Þ¤ì¤Þ¤¹¡£°ìÈÌŪ¤Ë¡¢¤³¤Î¥â¡¼¥É¤Ï¡¢¥é
¥¤¥È¥Ð¥Ã¥¯¤è¤ê¿¾¯ÃÙ¤¤Æ°ºî¤È¤Ê¤ê¤Þ¤¹¤¬¡¢¥¸¥ã¡¼¥Ê¥ë¥â¡¼¥É¤è¤ê¤Ï¤«¤Ê¤ê®¤¯¤Ê
¤ê¤Þ¤¹¡£

#* journal mode
#data=journal mode provides full data and metadata journaling.  All new data is
#written to the journal first, and then to its final location.
#In the event of a crash, the journal can be replayed, bringing both data and
#metadata into a consistent state.  This mode is the slowest except when data
#needs to be read from and written to disk at the same time where it
#outperforms all others modes.  Currently ext4 does not have delayed
#allocation support if this data journalling mode is selected.
* ¥¸¥ã¡¼¥Ê¥ë¥â¡¼¥É
data=journal ¥â¡¼¥É¤Ï¡¢¥Ç¡¼¥¿¤È¥á¥¿¥Ç¡¼¥¿¤Î´°Á´¤Ê¥¸¥ã¡¼¥Ê¥ê¥ó¥°¤òÈ÷¤¨¤Þ¤¹¡£
¤¹¤Ù¤Æ¤Î¿·¤·¤¤¥Ç¡¼¥¿¤Ï¡¢Àè¤Ë¥¸¥ã¡¼¥Ê¥ë¤Ë½ñ¤­¹þ¤Þ¤ì¡¢¤½¤Î¸å¤Ë½êÄê¤Î°ÌÃ֤ؽñ¤­
¤³¤Þ¤ì¤Þ¤¹¡£¥¯¥é¥Ã¥·¥å¤ÎºÝ¡¢¥¸¥ã¡¼¥Ê¥ë¤Ï¥ê¥×¥ì¥¤¤µ¤ì¡¢¥Ç¡¼¥¿¤È¥á¥¿¥Ç¡¼¥¿¤ÎξÊý
¤ÏÌ·½â¤Î̵¤¤¾õÂ֤˲óÉü¤µ¤ì¤Þ¤¹¡£¤³¤Î¥â¡¼¥É¤Ï¤â¤Ã¤È¤âÃÙ¤¤¤Ç¤¹¤¬¡¢¥Ç¥£¥¹¥¯¤Ø¤Î
¥Ç¡¼¥¿¤ÎÆɤߤÀ¤·¤È½ñ¤­¹þ¤ß¤òƱ»þ¤Ë¹Ô¤¦É¬Íפ¬¤¢¤ë»þ¤Ï¡¢Â¾¤Î¥â¡¼¥É¤è¤ê¹âÀ­Ç½¤Ç
¤¹¡£¸½ºß¤Î ext4 ¤Ç¤Ï¡¢¤³¤Î¥Ç¡¼¥¿¥¸¥ã¡¼¥Ê¥ê¥ó¥°¥â¡¼¥É¤¬ÁªÂò¤µ¤ì¤Æ¤¤¤ë¤È¤­¡¢
Ãٱ䥢¥í¥±¡¼¥·¥ç¥ó¤Ï¥µ¥Ý¡¼¥È¤µ¤ì¤Æ¤¤¤Þ¤»¤ó¡£

#References
#==========
»²¹Í»ñÎÁ
========

#kernel source: <file:fs/ext4/>
#               <file:fs/jbd2/>
¥«¡¼¥Í¥ë¥½¡¼¥¹: <file:fs/ext4/>
                <file:fs/jbd2/>

#programs:      http://e2fsprogs.sourceforge.net/
¥×¥í¥°¥é¥à:     http://e2fsprogs.sourceforge.net/

#useful links:  http://fedoraproject.org/wiki/ext3-devel
#               http://www.bullopensource.org/ext4/
#               http://ext4.wiki.kernel.org/index.php/Main_Page
#               http://fedoraproject.org/wiki/Features/Ext4
Ìò¤ËΩ¤Ä¥ê¥ó¥¯: http://fedoraproject.org/wiki/ext3-devel
                http://www.bullopensource.org/ext4/
                http://ext4.wiki.kernel.org/index.php/Main_Page
                http://fedoraproject.org/wiki/Features/Ext4