On Tuesday, 19 May 2020 17:51:40 CEST Richard W.M. Jones wrote: > Traditionally if you did live migration (KVM to KVM), you had to > ensure that cache=none was set on all disks of the guest up front. > This was because of quirks in how NFS works (I think the close-to-open > consistency and the fact that during live migration both qemus have > the file open), and we had to assume the worst case that a guest might > be backed by NFS. > > Because of this when virt-v2v converts a guest to run on KVM using > libvirt it sets cache=none. > > This is not necessary with modern qemu. If qemu supports the > drop-cache property of the file block driver, which libvirt will > automatically detect for us, then libvirt live migration is able to > tell qemu to drop cached data at the right time even if the backing is > NFS. > > It also had a significant performance impact. In some synthetic > benchmarks it could show 2 or 3 times slower performance. > > Thanks: Ming Xie, Peter Krempa. > ---
There is one additional occurrence of it in virt-v2v-output-local.pod. With that fixed, LGTM. Thanks, -- Pino Toscano
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