NAME
e2freefrag - report free space fragmentation information
SYNOPSIS
e2freefrag [ -c chunk_kb ] [ -h ] filesys
DESCRIPTION
e2freefrag is used to report free space fragmentation on ext2/3/4 file
systems. filesys is the filesystem device name (e.g. /dev/hdc1,
/dev/md0). The e2freefrag program will scan the block bitmap
information to check how many free blocks are present as contiguous and
aligned free space. The percentage of contiguous free blocks of size
and of alignment chunk_kb is reported. It also displays the
minimum/maximum/average free chunk size in the filesystem, along with a
histogram of all free chunks. This information can be used to gauge
the level of free space fragmentation in the filesystem.
OPTIONS
-c chunk_kb
If a chunk size is specified, then e2freefrag will print how
many free chunks of size chunk_kb are available in units of
kilobytes (Kb). The chunk size must be a power of two and be
larger than filesystem block size.
-h Print the usage of the program.
EXAMPLE
# e2freefrag /dev/vgroot/lvhome
Device: /dev/vgroot/lvhome
Blocksize: 4096 bytes
Total blocks: 1504085
Free blocks: 292995 (19.5%)
Min. free extent: 4 KB
Max. free extent: 24008 KB
Avg. free extent: 252 KB
HISTOGRAM OF FREE EXTENT SIZES:
Extent Size Range : Free extents Free Blocks Percent
4K... 8K- : 704 704 0.2%
8K... 16K- : 810 1979 0.7%
16K... 32K- : 843 4467 1.5%
32K... 64K- : 579 6263 2.1%
64K... 128K- : 493 11067 3.8%
128K... 256K- : 394 18097 6.2%
256K... 512K- : 281 25477 8.7%
512K... 1024K- : 253 44914 15.3%
1M... 2M- : 143 51897 17.7%
2M... 4M- : 73 50683 17.3%
4M... 8M- : 37 52417 17.9%
8M... 16M- : 7 19028 6.5%
16M... 32M- : 1 6002 2.0%
AUTHOR
This version of e2freefrag was written by Rupesh Thakare, and modified
by Andreas Dilger <adilger@sun.com>, and Kalpak Shah.
SEE ALSO
debugfs(8), dumpe2fs(8), e2fsck(8)