I just ran into "No space left on device" from Portage again. In such a situation previously I ran

# df -H

just to find that there was space left on all mounted devices! Confused I deleted a few distfiles through

# rm -vf /usr/portage/distfiles/*

and found Portage to work again magically. This time I remembered a chat with rbu: Inodes can run out, too.

Checking the number of free inodes I was in trouble indeed:

# df -i -H
Filesystem            Inodes   IUsed   IFree IUse% Mounted on
..
/dev/sda7               1.3M    1.3M       1  100% /var
..

That's all I wanted to share.

(PS: With /var on a different partition now deleting distfiles no longer helps...)