dumpfs(1M) DG/UX R4.11 dumpfs(1M)
NAME
dumpfs - dump file system information
SYNOPSIS
/usr/sbin/dumpfs filesys|special
where:
filesys The pathname of a directory in /etc/fstab. If this argument
is present, the device associated with that pathname will be
processed.
special The pathname of a special file for a device on which a file
system resides
DESCRIPTION
Dumpfs lists all super-block and disk allocation region (DAR)
information for a file system. A DAR is an allocation grouping used
to distribute files over a disk. It consists of three parts. The
first two parts are of a fixed size. The first fixed portion is the
bitmap of allocated data blocks in the DAR. The second fixed portion
is the inode table for the allocation group. The last portion of the
DAR is the actual space used for the files of the file system.
There are three sections of output by dumpfs:
1) superblock-related information
2) summary contents of the DAR entry table (DARE)
3) information for each DAR
Superblock Information
The following is printed:
· File system ID (fsid)
· minor device number
· DAR size
· number of inodes per DAR
· whether the file system is quiet (A quiet file system will not
need to be fscked if the system crashes, since there are no
modified pages in memory that have not been flushed back to
stable storage)
· file system name (fname)
· fpack (file system pack name)
· data element size
· index element size
· directory data element size
· directory index element size
· 1st and 2nd anniversaries (facilities that control the
allocation of disk resources for each file in the file system)
· number of DARs
· number of usable blocks in the file system
· actual number of blocks in file system
· number of allocated inodes
· number of free inodes
· number of data blocks
DARE Table Information
The following is printed:
· number of allocated inodes
· number of allocated data blocks
· number of directories in the DAR
DAR Information
The following is printed:
· number of allocated inodes
· number of directories in the DAR
· list of free data blocks
· number of allocated data blocks
· histogram of the free data block sizes in the DAR
When summing up the sizes of the free data blocks, the bitmap is
scanned starting with the bits representing the data area. The file
system block allocation algorithms do not count any sequence of
``data element size'' free bits in the bitmap as a free data element.
Contiguous data blocks will only be allocated as a data element if
the sequence of bits in the bitmap are aligned on a ``data element
size'' boundary. For example, if the data element size of the file
system is 16 blocks, a data element will only be allocated if a
sequence of 16 free bits in the bitmap are aligned on a 16-bit (word)
boundary in the bitmap. This holds true for data element sizes up to
32 blocks, but any data element size greater than 32 blocks will
search starting on any 32-bit (long word) boundary.
SEE ALSO
fsck(1M), mkfs(1M), tunefs(1M), fs(4), fstab(4).
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