The metastore provider relys on the filesystem Extended Attributes, this feature must thus be active on the underlying FS. This generally requires the following

- Linux filesystem supporting xattr (ext2/3/4, xfs, ReiserFs, hfs, etc).
- xattr package installed (apt-get install xattr on Debian 6 for example)
- libattr library installed (apt-get install libattr1-dev on Debian 6 for example)
- The filesystem must be mounted with the xattr attributes enabled, generaly by adding the user_xattr parameter in the /etc/fstab line.
- And finally, the PHP xattr extension (pecl install xattr)

Once activated, various metadata will be stored directly along with the filesystem nodes themselves, avoiding ajaxplorer to have to monitor and update the metadata on the various files operation (move/delete).

This can be recommended if you plan to let your users accessing the filesystem via another channel than ajaxplorer (e.g. samba, direct ftp, etc). In this latter case, warning, it does not exempt you of setting up some synchronization mechanism to trigger events in the backend, to be sure all indexes are up-to-date, and various hooks are correctly triggered.