E2FREEFRAG

Section: Maintenance Commands (8)
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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.