3. EXT3 Definition
• ext3, or third extended
filesystem, is a
journaled file system
that is commonly used
by the Linux kernel.
4. More About EXT3
• It adds the following features to ext2 : a journal, online
file system growth, HTree indexing for larger directories.
• Without these features, any ext3 file is also a valid ext2
file.
• ext3 lacks "modern" filesystem features, such as
dynamic inode allocation and extents.
• The max number of blocks for ext3 is 232. The size of a
block can vary, affecting the max number of files and the
max size of the file system
6. Journal( lowest risk )
• Both metadata and file contents
are written to the journal before
being committed to the main file
system.
• Because the journal is relatively
continuous on disk, this can
improve performance, if the journal
has enough space.
• In other cases, performance gets
worse, because the data must be
written twice—once to the journal,
and once to the main part of the
filesystem.
7. Ordered( medium risk )
• Only metadata is journaled; file
contents are not, but it's guaranteed
that file contents are written to disk
before associated metadata is
marked as committed in the journal.
• This is the default on many Linux
distributions.
• If there is a power outage or kernel
panic while a file is being written or
appended to, the journal will indicate
that the new file or appended data
has not been "committed", so it will
be purged by the cleanup process.
8. Writeback( highest risk )
• Only metadata is
journaled; file contents
are not.
• The contents might be
written before or after the
journal is updated.
• As a result, files modified
right before a crash can
become corrupted.
10. EXT4 Definition
• ext4 was born as a series
of backward compatible
extensions to ext3, many
of them originally
developed by Cluster File
Systems for the Lustre file
system between 2003 and
2006, meant to extend
storage limits and add
other performance
improvements.
11. More About EXT4
• The ext4 filesystem can support volumes with sizes up to 1
exbibyte (EiB) and files with sizes up to 16 tebibytes (TiB)
• ext4 is backward compatible with ext3 and ext2, making it
possible to mount ext3 and ext2 as ext4.
• ext4 can pre-allocate on-disk space for a file. To do this on
most file systems, zeros would be written to the file when
created.
• ext4 uses a performance technique called allocate-on-flush
also known as delayed allocation.
13. Ext3 stands for third extended
file system.
Ext4 stands for fourth extended
file system.
It was introduced in 2001.
Developed by Stephen Tweedie.
It was introduced in 2008.
The main benefit of ext3 is that it
allows journaling.
Supports huge individual file size
and overall file system size
Starting from Linux Kernel 2.4.15
ext3 was available.
Starting from Linux Kernel 2.6.19
ext4 was available.
