[CentOS] is it possible to resive /var online?

> That's exactly as I thought :)
> For now, a safer way around this, I moved the /var/lib/xend/saved folder
> to it's own LVM volume, and re-mounted it on /var/lib/xend.
> So now /var has 1.4GB free space from 2GB
>

2G for /var still looks a bit on the small side to me...

/var can be umounted if necessary. Just stop all daemons that write to 
it and anything else that reads or otherwise has a file handle under 
/var. Been there, done that.