Hardware: one virtualization server. Dual Nehalem, 24GB RAM, 2 TB mirrored HD. Software: Debian, KVM, virt-manager on the server with several virtual machines that use Linux too. 2 TB Disk is a big LVM, each VM gets a logical volume and makes its own partitions in that. Problem: One of the programs that runs on one of the VMs creates huge disk load. This never was an issue, because the program never ran on such a powerful hardware. Now the CPUs are fast, and lots of I/O is the result. We cant do much against that at the moment, because the tool is a black box. On the other hand, the speedy computation is welcome. The program creates about 5 GB of temp files which get overwritten during the next iteration. Question: How can we limit the disk I/O for the process?