duv User Manual
duv version 2.0 2005-11-01
Last updated 2005-11-01
BitWagon Software LLC
http://www.BitWagon.com
duv overview
Accounting for disk space
Installing duv
Invocation and input
Limitations
Tips
Copyright © 2001, 2005 BitWagon Software LLC. All rights reserved.
duv overview
duvTM Visual
Disk Usage lets you see where the disk space went. duv draws a multicolor
picture with area proportional to disk usage. The picture may be
based on file and directory hierarchy, ownership, last portion of filename,
or number of days since last access or modification. As you move
the pointer over the display, duv annotates the filename and size.
As you enter commands via keyboard or button clicks, duv enters or leaves
portions of the hierarchy, sorts the displayed regions by size, or does
a print/copy/clip of the complete pathname. duv also can display
remaining free space, and generate a PostScript rendering of the current picture
for printing.
Disk space accounting
duv accounts for space used by a file as, "How much more free space would
there be if the file were deleted?" This works well until there are
links. In UNIX file systems, space is really allocated for inodes,
and a filename is just a pointer to the inode. If there is only one
pointer to an inode then it is easy to think of the space as belonging
to the filename. But if there are two or more filenames linked to
an inode, then it is no longer so easy. duv handles this by constructing
a top level pseudo directory called &
with a sub directory for each regular file inode that has two or more links.
The entries in the sub directory are the complete pathnames that are linked
to the inode. The space for the inode is divided evenly among the links,
with any remainder assigned to the sub directory. Soft links (/bin/ln
-s) are just name-to-name translations. If the name of the target
is short enough (59 bytes or less on ext2) then the soft link itself takes
no space other than directory space in the origin directory.
The space required to make a backup copy on a storage medium can be
either more or less than the usage reported by duv, depending on the use
of compression, filtering (selection based on name, ownership, permissions,
time of last access or modification, etc.), policies with regard to
links, and
recognition of blocks which are all zero.
Installing duv
duv is distributed as a compressed tarball source archive,
and as pre-compiled executables for i586, x86_64, and ppc32.
Build an executable from source,
or put the appropriate pre-compiled executable somewhere in $PATH,
such as $HOME/bin, /usr/local/bin, etc.
Running duv
duv flags... paths...
duv prints a banner and all query output to stderr.
duv flags
| short | long | description |
| --help |
print usage summary, then exit |
| -ln | --lg=n |
set logical display size to 2**n dots; default n=16 |
| -mn | --magnify=n |
set dot size to n by n pixels; default 2 by 2 |
| -h | --horizontal |
horizontal orientation (landscape) when 2:1 (default) |
| -v | --vertical |
vertical orientation (portrait) when 2:1 |
| -P"cmd" | --print="lpr" |
print filter command; substitutions: %n serial number;
%k kind (stroke, fill, text) |
| -L | --nolinks |
force n_hardlink==1 (some DVD/CD) |
| -M | --nomount |
do not traverse mount points |
| -un | --uids=n |
restrict to n UID lookups; default 10 |
| -gn | --gids=n |
restrict to n GID lookups; default 10 |
| -wn | --fdlimit=n |
restrict to n file descriptors; default 512 |
| -8 | |
TrueColor display acts as 8-bit PseudoColor instead |
| -a | --noannotate |
omit annotation of name and size |
| -f | --nofree |
omit free space |
| -c | --nocopy |
omit copy of pathname |
| -k | --noclip |
omit clip of pathname |
| -p | --noprint |
omit print of pathname |
| -- |
optional explicit end of flags |
duv input
| action | key | button |
| print+copy+clip pathname | any unused |
Button1 |
| enter directory | + F5 F4 |
Shift+Button1 |
| leave directory | - F6 F3 |
Control+Button1 |
| sort by size | * F7 F2 |
Control+Shift+Button1 |
| cycle dir->uid-> .->aday->mday | / F8 F1 |
Mod1Mask+Button1 |
| move pointer dot-by-dot | arrow keys |
| print text to --print filter |
# | [%k==>3] |
| (stroke) print PostScript to --print filter |
! | [%k==>1] |
| (fill) print PostScript to --print filter |
% | [%k==>5] |
Limitations
- Total disk usage must be less than 2TB (2048GB; 2**41 bytes).
- The number of file systems must not exceed 128.
- The product of the total number of files times the number of
file systems must not exceed 2**31.
- The number of entries in a single directory must be less than 1,048,576.
- The number of distinct uids or gids must not exceed 2**24 (16M).
Tips
In many cases, adding the option nodiratime to /etc/fstab
will enable faster data gathering. Example:
| /dev/hda7 /home ext2 defaults,nodiratime 1 2 |
Caution: Some backup programs may use time of last access to a directory
to make decisions about what to backup. Consult the documentation for your
backup program, or ask your system administrator.
On a busy system, or when several instances of duv are gathering data
at the same time, it may be more friendly to use the invocation option
--fdlimit=64 to reduce the chance that other processes
will run out of file descriptors. duv copes dynamically, but many
other processes do not.
On some systems, converting every numerical UID to a username can
take a long time. Adjust with --uids=n, which limits
lookups to the UIDs with the largest usage.
If the usage reported by duv does not seem right, then please use standard
utilities (du, df, ls, sort, etc.) instead.