I have taken the fisheye instance done for the time being - its resource usage was just too high and I am not entirely sure but I suspect it was the cause of the recent disk problems, by that I mean that it was hogging resources logs were huge. 

For now I have added a SVN gateway addon to JIRA that will provide the SVN changesets for each jira

Its not as full featured as fisheye but if or when we move off SVN it will make fisheye defunct anyway.

This has dropped our memory usage from 85% AV TO 40% ....whichs gives us a bit more headroom.

Ben