As the title says it, I think it'll be better to switch to sparse file preallocation in order to handle space more efficiently and not trash the disk (for a long time, especially for big torrents)

I think you mean sparse. And that doesn't work on all file systems, so it's not as simple as enabling it.

Well, it certainly works on most modern UNIX file systems (ext2/3/4, xfs, jfs, reiserfs, ffs, btrfs, ufs, etc) and on ntfs. Dunno for fat, but I know hfs+ doesn't support sparse files. We could simple have a checkbox next to the preallocation one where user can choose full preallocation or sparse file one. Better yet, have a drop-down to select between full and sparse. I hate the fact that I need to wait more than a minute in order for ktorrent to preallocate a big torrent - try waiting for it to preallocate a torrent of 30GB and see for yourself

By default ktorrent creates sparse files (if the filesystem supports it). Only on file systems which do not support sparse files (fat mostly) or when you have enabled "Fully reserve diskspace", will ktorrent not use sparse files.

@George

Ah, so enabling "Reserve disk space before starting a torrent" = sparse file mode
and only if "fully reserve disk space" is enable = non-sparse mode, thus slower

??