edit:
I didn't seen any bug reports about this so I added one bug report.
How much space does /var/cache/pacman have and how much space does pacman need? Compare those two values and tell us the results.
Pacman needs a block for each 4Kio it needs to download, for example 1813 blocks to download 7,06 MiB.
Virtually I have all my RAM (2GB) for /tmp and /var/cache/pacman but df seems to be lost:
$ df /var/cache/pacman /tmp
Filesystem 1K-blocks Used Available Use% Mounted on
none 0 0 0 - /var/cache/pacman
none 0 0 0 - /tmp
If I disable CheckSpace in pacman.conf I can download again, but I don't think it was disabled in 4.0.
Is there a reason why you're using ramfs instead of tmpfs? The former isn't going to use the virtual memory subsystem very effectively, and it's probably not what you want. tmpfs on the other hand is quite willing to use swap as a backing store, which probably would mitigate this issue.
I discovered ramfs on the wiki and it was what I was looking for at this time.
Because I never knew the optimal value I should put for the tmpfs limit and my ram usage varies a lot, I thought that ramfs was a better choice.
On my fstab, I have a line to create the pacman download cache:
none /var/cache/pacman ramfs defaults 0 0
It worked fine until I updated to pacman 4.1 - no problem during the installation, and I merged the pacman.conf - but now, everytime I try to install the upgrade I get this error:
error: Partition /var/cache/pacman too full: 559 blocks needed, 0 blocks free
error: failed to commit transaction (not enough free disk space)
Should I open a bug report?
]]>