What is fsdb?
fsdb is a small collection of programs that speed up the creation of
secure locate file indexes to the point where a completely up to date
database is possible.
Where can I download fsdb?
fsdb is available for download from the SourceForge project page.
Installation instructions are included with the distribution.
How does it work?
fsdb is split up into a four different parts (see
- A kernel patch to add a hook into the dnotify mechanism.
- A loadable kernel module to take advantage of the dnotify_hook
by keeping a list of changed directory inodes. The kernel module
exports a character device interface. The minor number is dynamically
assigned by the "misc" driver (see /proc/misc). The major number is 10.
If devfs is used the device file should automatically appear as
- A daemon (called fsupdate) which connects to the device file
and reads the
inodes from the kernel. It publishes a unix socket interface
(/var/lib/fsdb/fsupdate.sock) and keeps the inodes stored in
/var/lib/fsupdate.txt for persistent storage.
- A program to generate file system databases,
fsdb. This program takes
many of the arguments that updatedb (slocate) does, specifically it
process /etc/updatedb.conf and also understands the prune paths (-e) and
prune filesystems (-f) switches. Additionally fsdb can produce an slocate
database for use with slocate for high performance searching.
Additionally some scripts are provided for easy integration:
- cron job to update the database. I schedule it one every hour.
- init script to load the kernel module.
- ilocate script performs a fast update of the database before invoking locate
How much overhead is fsdb?
- The kernel module is very simple and is unlikely to add more
overhead than a mouse driver, depending on how fast directories are
changing in your system.
- The fsupdate daemon reads from the kernel modules, so it will take up some memory. On my system it takes up total size of 2252 kb with 456 kb resident. This memory usage could be reduced by rewriting fsupdate in C (it is currently a C++) program.
- On my system, the cron job takes about 1-3 seconds to update the database:
# time /etc/cron.hourly/fsdb.cron
- Intermediate locates are fast:
$ time ilocate slocate.txt