FSANALYZE

Section: Maintenance Commands (8)
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NAME

fsanalyze - a file system analyzer tool

SYNOPSIS

fsanalyze [ -deio ] special [ files ]

DESCRIPTION

Fsanalyze is a simple tool that estimates file or file system fragmentation. It accomplishes this by scanning the data blocks of each inode looking for block numbers that are out of sequence. In effect, it is counting the number of disk seeks required to read a file sequentially. Fragmentation is then computed as the ratio of actual "seeks" to the potential number "seeks" which would be required if the file were completely fragmented.

If the optional files argument is omitted, fsanalyze will analyze the entire file system specified by the special argument. Special must be a block-oriented file system device. Fsanalyze reports various statistics regarding file system usage and data-block indirection, plus a list of the 10 most fragmented inodes in the file system. The 10 most fragmented files are listed in decreasing order of fragmentation based on the absolute number of fragments. For example a 100-block file that contains 40 individual fragments is 39.39% fragmented (39 seeks / 99 potential seeks), but is listed before a 2-block file that contains 2 fragments (100% fragmented).

If the files argument is present, fsanalyze will report the fragmentation of the designated files only.

Before performing any analysis, fsanalyze checks the file system integrity by invoking fsstat (1M). If the file system needs to be checked, fsanalyze terminates with a message to that effect. If a non-root file system is mounted, a warning message is displayed, but analysis continues. When used on a mounted file system, it is recommended that a sync (1) be performed immediately prior to running fsanalyze . If sync (1) is not performed, the file system will not be damaged, but erroneous statistics may be reported.

OPTIONS

-d: display inode numbers as they are examined. This flag makes it easy to chart the progress of fsanalyze through the file system. Used mainly for debugging.
-e: report file size inconsistencies - the inode numbers are reported for files where the file size and number of data blocks are inconsistent. This option provides the same information as fsck (1) phase 1.
-i: report double and triple indirection - the inode numbers are reported for files that contain double and/or triple data-block indirection.
-o: overrides file system integrity checks. The file system will be analyzed even if fsstat (1M) reports that it is damaged. Note that fsanalyze may give erroneous results if used on a damaged file system, but the file system itself will not be affected.

EXAMPLES

fsanalyze /dev/dsk/0s2 # analyze file system
fsanalyze /dev/dsk/0s2 * # analyze files in current dir

FILES

/usr/include/sys/filesys.h     super block structure

/usr/include/sys/ino.h         disk inode structure

/usr/include/sys/param.h       system parameters

/usr/include/sys/types.h       system type definitions

BUGS

Fsanalyze is supported by System V Release 2. It has not yet been ported to any other version of Unix.

AUTHOR

Michael J. Young
{decvax|harvard|linus|mit-eddie}!necntc!necis!mrst!sdti!mjy
Internet : mjy%sdti.uucp@harvard.harvard.edu

VERSION

v2.04 - 7 January 1988

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