Re: [PATCH 0/3] virtio-blk: support zoned block devices

On Tue, 20 Sept 2022 at 03:43, Christoph Hellwig [off-list ref] wrote:

On Sun, Sep 18, 2022 at 10:29:18PM -0400, Dmitry Fomichev wrote:

quoted

In its current form, the virtio protocol for block devices (virtio-blk)
is not aware of zoned block devices (ZBDs) but it allows the driver to
successfully scan a host-managed drive provided by the virtio block
device. As the result, the host-managed drive is recognized by the
virtio driver as a regular, non-zoned drive that will operate
erroneously under the most common write workloads. Host-aware ZBDs are
currently usable, but their performance may not be optimal because the
driver can only see them as non-zoned block devices.

What is the advantage in extending virtio-blk vs just using virtio-scsi
or nvme with shadow doorbells that just work?

virtio-blk is widely used and new request types are added as needed.

QEMU's NVMe emulation may support passing through zoned storage
devices in the future but it doesn't today. Support was implemented in
virtio-blk first because NVMe emulation isn't widely used in
production QEMU VMs.

Stefan