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?
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?
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.
