On 06/09/2011 08:21 PM, Emmanuel Noobadmin wrote: > But now that you brought it up, I'm wondering if that would had been > pointless. If the kernel considers KVM opening the diskfile and > holding onto it as a single access, regardless of how many subsequent > reads/writes there are, then this wouldn't make a difference would it? atime and mtime are updated for *every* read and write operation, not for the open() of the file. That aside, if you're running KVM I strongly recommend using LVM rather than file-backed VM guests. It's more work to set up, but you'll see drastically better IO performance in the guests. One system that I measured had a write speed of around 8 MB/s for sequential block output on file-backed VMs. LVM backed VMs wrote at around 56 MB/s for sequential block output. You should *never* used file-backed VMs for production systems.