Hannes Reinecke <h...@suse.de> 于2022年10月10日周一 14:19写道： > > On 10/10/22 04:21, Sam Li wrote: > > Add the documentation about the zoned device support to virtio-blk > > emulation. > > > > Signed-off-by: Sam Li <faithilike...@gmail.com> > > Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com> > > --- > > docs/devel/zoned-storage.rst | 40 ++++++++++++++++++++++++++ > > docs/system/qemu-block-drivers.rst.inc | 6 ++++ > > 2 files changed, 46 insertions(+) > > create mode 100644 docs/devel/zoned-storage.rst > > > > diff --git a/docs/devel/zoned-storage.rst b/docs/devel/zoned-storage.rst > > new file mode 100644 > > index 0000000000..deaa4ce99b > > --- /dev/null > > +++ b/docs/devel/zoned-storage.rst > > @@ -0,0 +1,40 @@ > > +============= > > +zoned-storage > > +============= > > + > > +Zoned Block Devices (ZBDs) devide the LBA space into block regions called > > zones > > divide > > > +that are larger than the LBA size. They can only allow sequential writes, > > which > > +can reduce write amplification in SSDs, and potentially lead to higher > > +throughput and increased capacity. More details about ZBDs can be found at: > > + > > +https://zonedstorage.io/docs/introduction/zoned-storage > > + > > +1. Block layer APIs for zoned storage > > +------------------------------------- > > +QEMU block layer has three zoned storage model: > > +- BLK_Z_HM: This model only allows sequential writes access. It supports a > > set > > +of ZBD-specific I/O request that used by the host to manage device zones. > > Maybe: > This model only allow for sequential write access to zones. It supports > ZBD-specific I/O requests to manage device zones. > > > +- BLK_Z_HA: It deals with both sequential writes and random writes access. > > Maybe better: > This model allows sequential and random writes to zones. It supports > ZBD-specific I/O requests to manage device zones. > > > +- BLK_Z_NONE: Regular block devices and drive-managed ZBDs are treated as > > +non-zoned devices. > > Maybe: > This is the default model with no zones support; it includes both > regular and drive-managed ZBD devices. ZBD-specific I/O requests are not > supported.
Thanks! > > > + > > +The block device information resides inside BlockDriverState. QEMU uses > > +BlockLimits struct(BlockDriverState::bl) that is continuously accessed by > > the > > +block layer while processing I/O requests. A BlockBackend has a root > > pointer to > > +a BlockDriverState graph(for example, raw format on top of file-posix). The > > +zoned storage information can be propagated from the leaf BlockDriverState > > all > > +the way up to the BlockBackend. If the zoned storage model in file-posix is > > +set to BLK_Z_HM, then block drivers will declare support for zoned host > > device. > > + > > +The block layer APIs support commands needed for zoned storage devices, > > +including report zones, four zone operations, and zone append. > > + > > +2. Emulating zoned storage controllers > > +-------------------------------------- > > +When the BlockBackend's BlockLimits model reports a zoned storage device, > > users > > +like the virtio-blk emulation or the qemu-io-cmds.c utility can use block > > layer > > +APIs for zoned storage emulation or testing. > > + > > +For example, to test zone_report on a null_blk device using qemu-io is: > > +$ path/to/qemu-io --image-opts -n > > driver=zoned_host_device,filename=/dev/nullb0 > > +-c "zrp offset nr_zones" > > diff --git a/docs/system/qemu-block-drivers.rst.inc > > b/docs/system/qemu-block-drivers.rst.inc > > index dfe5d2293d..0b97227fd9 100644 > > --- a/docs/system/qemu-block-drivers.rst.inc > > +++ b/docs/system/qemu-block-drivers.rst.inc > > @@ -430,6 +430,12 @@ Hard disks > > you may corrupt your host data (use the ``-snapshot`` command > > line option or modify the device permissions accordingly). > > > > +Zoned block devices > > + Zoned block devices can be passed through to the guest if the emulated > > storage > > + controller supports zoned storage. Use ``--blockdev zoned_host_device, > > + node-name=drive0,filename=/dev/nullb0`` to pass through ``/dev/nullb0`` > > + as ``drive0``. > > + > > Windows > > ^^^^^^^ > > > > Cheers, > > Hannes > -- > Dr. Hannes Reinecke Kernel Storage Architect > h...@suse.de +49 911 74053 688 > SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg > HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew > Myers, Andrew McDonald, Martje Boudien Moerman >
