[xwiki-users] control the size of the attachments temp storage?

Hello XWiki experts, at www.curriki.org, our two server-nodes are reaching limits in terms of storage. One of the things that take a lot of space are the logs, we have a clue how to manage that. Another thing that takes a lot of space is /var/tmp/ which contains temporary storages for the attachment deliveries. On one of the nodes, it's made of 14Gb and 12538 files. On the other, 23Gb and 29402 files. What are the risk of deleting the old files there? Is the server touching the files when it has served them so that files older than a day could be deleted if we need? (I think I know that it takes more time to deliver from the DB and create temp-storage than to use the temp storage) thanks in advance Paul