Troels Arvin wrote:
Hello,

I'm conducting some performancetests with KVM-virtualized CentOSes. One thing I noticed is that guest I/O performance seems to be significantly better for virtio-based block devices ("drive"s) if the cache=none argument is used. (This was with a rather powerful storage system backend which is hard to saturate.)

So: Why isn't cache=none be the default for drives?

Is that the right question? Or is the right question "Why is cache=none faster?"

What did you use for measuring the performance? I have found in the past that virtio block device was slower than IDE block device emulation.

Gordan
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