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'-o barriers=[0|1]' mount option for both ext3 and ext4 filesystems
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for a fair comparison. When tuning ext3 for best benchmark numbers,
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it is often worthwhile to try changing the data journaling mode; '-o
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data=writeback,nobh' can be faster for some workloads. (Note
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however that running mounted with data=writeback can potentially
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leave stale data exposed in recently written files in case of an
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unclean shutdown, which could be a security exposure in some
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situations.) Configuring the filesystem with a large journal can
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also be helpful for metadata-intensive workloads.
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data=writeback' can be faster for some workloads. (Note however that
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running mounted with data=writeback can potentially leave stale data
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exposed in recently written files in case of an unclean shutdown,
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which could be a security exposure in some situations.) Configuring
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the filesystem with a large journal can also be helpful for
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metadata-intensive workloads.
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lead to any number of problems.
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data=journal All data are committed into the journal prior to being
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written into the main file system.
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written into the main file system. Enabling
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this mode will disable delayed allocation and
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data=ordered (*) All data are forced directly out to the main file
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system prior to its metadata being committed to the
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table readahead algorithm will pre-read into
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the buffer cache. The default value is 32 blocks.
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orlov (*) This enables the new Orlov block allocator. It is
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oldalloc This disables the Orlov block allocator and enables
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the old block allocator. Orlov should have better
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performance - we'd like to get some feedback if it's
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the contrary for you.
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user_xattr Enables Extended User Attributes. Additionally, you
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need to have extended attribute support enabled in the
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kernel configuration (CONFIG_EXT4_FS_XATTR). See the
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attr(5) manual page and http://acl.bestbits.at/ to
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learn more about extended attributes.
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nouser_xattr Disables Extended User Attributes.
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acl Enables POSIX Access Control Lists support.
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Additionally, you need to have ACL support enabled in
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the kernel configuration (CONFIG_EXT4_FS_POSIX_ACL).
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See the acl(5) manual page and http://acl.bestbits.at/
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for more information.
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nouser_xattr Disables Extended User Attributes. If you have extended
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attribute support enabled in the kernel configuration
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(CONFIG_EXT4_FS_XATTR), extended attribute support
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is enabled by default on mount. See the attr(5) manual
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page and http://acl.bestbits.at/ for more information
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about extended attributes.
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noacl This option disables POSIX Access Control List
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support. If ACL support is enabled in the kernel
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configuration (CONFIG_EXT4_FS_POSIX_ACL), ACL is
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enabled by default on mount. See the acl(5) manual
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page and http://acl.bestbits.at/ for more information
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bsddf (*) Make 'df' act like BSD.
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minixdf Make 'df' act like Minix.
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package for more details
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(http://sourceforge.net/projects/linuxquota).
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bh (*) ext4 associates buffer heads to data pages to
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nobh (a) cache disk block mapping information
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(b) link pages into transaction to provide
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"bh" option forces use of buffer heads.
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"nobh" option tries to avoid associating buffer
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heads (supported only for "writeback" mode).
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stripe=n Number of filesystem blocks that mballoc will try
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to use for allocation size and alignment. For RAID5/6
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systems this should be the number of data
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write and convert the extent to initialized after IO
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completes. This approach allows ext4 code to avoid
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using inode mutex, which improves scalability on high
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speed storages. However this does not work with nobh
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option and the mount will fail. Nor does it work with
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speed storages. However this does not work with
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data journaling and dioread_nolock option will be
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ignored with kernel warning. Note that dioread_nolock
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code path is only used for extent-based files.
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In the event of a crash, the journal can be replayed, bringing both data and
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metadata into a consistent state. This mode is the slowest except when data
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needs to be read from and written to disk at the same time where it
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outperforms all others modes. Currently ext4 does not have delayed
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allocation support if this data journalling mode is selected.
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outperforms all others modes. Enabling this mode will disable delayed
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allocation and O_DIRECT support.