I've tried creating a separate user account for rtorrent and sickbeard (a torrent downloader) so everything isn't running as root but I've bitten off more than I can chew.
I've chmodded 2770 (setgid, user+group ALL) and am sure 'sickbeard' is in the 'users' group, as is rtorrent. Sickbeard is still complaining that it can't write. I've even tried 'su sickbeard', navigated to the directory, and touching to create a file and it works perfectly. I am sure sickbeard is running as the user sickbeard, I've checked in htop.
Here is some output that might be of use:
sickbeard@parsnip:/media/store1/torrents$ groups
sickbeard users
rtorrent@parsnip:/media/store1/torrents$ groups
rtorrent users
root@parsnip:/media/store1/torrents# ls -lha
total 268K
drwxrws--- 7 rtorrent users 4.0K Mar 27 16:46 .
drwxrws--- 11 root users 4.0K Mar 27 17:03 ..
drwxrws--- 4 rtorrent users 4.0K Mar 27 16:26 complete
drwxrws--- 4 rtorrent users 4.0K Mar 27 16:46 download
drwxrws--- 2 rtorrent users 244K Mar 27 16:42 session
drwxrws--- 2 rtorrent users 4.0K Mar 27 13:56 uploads
drwxrws--- 4 rtorrent users 4.0K Mar 27 16:25 watch
rtorrent@parsnip:/media/store1/torrents/watch/tv$ ls -lha
total 12K
drwxrws--- 3 rtorrent users 4.0K Mar 27 16:25 .
drwxrws--- 4 rtorrent users 4.0K Mar 27 16:25 ..
drwxrws--- 2 rtorrent users 4.0K Mar 27 17:09 sickbeard
Hopefully a unix pro can point out where I'm going wrong.
EDIT: There is definitely something strange going on. The conflicting info below has me puzzled - I haven't changed a thing since the above.
parsnip@parsnip:~$ sudo grep -e '^users:' /etc/gshadow
users:*::xbmc,sickbeard,rtorrent,parsnip,root
parsnip@parsnip:~$ sudo grep -e '^users:' /etc/group
users:x:100:xbmc,sickbeard,rtorrent,parsnip,root
parsnip@parsnip:~$ groups
parsnip adm cdrom sudo dip plugdev lpadmin sambashare
parsnip@parsnip:~$ cd /media/store1/torrents/complete/tv/sickbeard
-bash: cd: /media/store1/torrents/complete/tv/sickbeard: Permission denied
parsnip@parsnip:~$ su sickbeard
sickbeard@parsnip:/home/parsnip$ groups
sickbeard users
sickbeard@parsnip:/home/parsnip$ cd /media/store1/torrents/complete/tv/sickbeard
sickbeard@parsnip:/media/store1/torrents/complete/tv/sickbeard$ exit
exit
parsnip@parsnip:~$ cd /media/store1/torrents/complete/tv/sickbeard
-bash: cd: /media/store1/torrents/complete/tv/sickbeard: Permission denied