Signed-off-by: Markus Frank <m.fr...@proxmox.com> --- qm.adoc | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 82 insertions(+), 2 deletions(-)
diff --git a/qm.adoc b/qm.adoc index c4f1024..571c42e 100644 --- a/qm.adoc +++ b/qm.adoc @@ -996,6 +996,85 @@ recommended to always use a limiter to avoid guests using too many host resources. If desired, a value of '0' for `max_bytes` can be used to disable all limits. +[[qm_virtiofs]] +Virtio-fs +~~~~~~~~~ + +Virtio-fs is a shared file system, that enables sharing a directory between +host and guest VM while taking advantage of the locality of virtual machines +and the hypervisor to get a higher throughput than 9p. + +To use virtio-fs, the https://gitlab.com/virtio-fs/virtiofsd[virtiofsd] daemon +needs to run in the background. +In {pve} this process starts immediately before the start of QEMU. + +Linux VMs with kernel >=5.4 support this feature by default. + +There is a guide available on how to utilize virtio-fs in Windows VMs. +https://github.com/virtio-win/kvm-guest-drivers-windows/wiki/Virtiofs:-Shared-file-system + +Known limitations +^^^^^^^^^^^^^^^^^ + +* Virtiofsd crashing means no recovery until VM is fully stopped +and restarted. +* Virtiofsd not responding may result in NFS-like hanging access in the VM. +* Memory hotplug does not work in combination with virtio-fs. +* Windows cannot understand ACLs. Therefore, disable it for Windows VMs, +otherwise the virtio-fs device will not be visible within the VMs. + +Add mapping for Shared Directories +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +To add a mapping, either use the API directly with pvesh as described in the +xref:resource_mapping[Resource Mapping] section, +or add the mapping to the configuration file `/etc/pve/mapping/dir.cfg`: + +---- +some-dir-id + map node=node1,path=/mnt/share/,submounts=1 + map node=node2,path=/mnt/share/, + xattr 1 + acl 1 +---- + +Set `submounts` to `1` when multiple file systems are mounted in a +shared directory. + +Add virtio-fs to VM +^^^^^^^^^^^^^^^^^^^ + +To share a directory using virtio-fs, you need to specify the directory ID +(dirid) that has been configured in the Resource Mapping. +Additionally, you can set the `cache` option to either `always`, `never`, +or `auto`, depending on your requirements. +If you want virtio-fs to honor the `O_DIRECT` flag, you can set the +`direct-io` parameter to `1`. +Additionally it possible to overwrite the default mapping settings +for xattr & acl by setting then to either `1` or `0`. + +The `acl` parameter automatically implies `xattr`, that is, it makes no +difference whether you set xattr to `0` if acl is set to `1`. + +---- +qm set <vmid> -virtiofs0 dirid=<dirid>,cache=always,direct-io=1 +qm set <vmid> -virtiofs1 <dirid>,cache=never,xattr=1 +qm set <vmid> -virtiofs2 <dirid>,acl=1 +---- + +To mount virtio-fs in a guest VM with the Linux kernel virtio-fs driver, run the +following command: + +The dirid associated with the path on the current node is also used as the +mount tag (name used to mount the device on the guest). + +---- +mount -t virtiofs <mount tag> <mount point> +---- + +For more information on available virtiofsd parameters, see the +https://gitlab.com/virtio-fs/virtiofsd[GitLab virtiofsd project page]. + [[qm_bootorder]] Device Boot Order ~~~~~~~~~~~~~~~~~ @@ -1603,8 +1682,9 @@ in the relevant tab in the `Resource Mappings` category, or on the cli with [thumbnail="screenshot/gui-datacenter-mapping-pci-edit.png"] -Where `<type>` is the hardware type (currently either `pci` or `usb`) and -`<options>` are the device mappings and other configuration parameters. +Where `<type>` is the hardware type (currently either `pci`, `usb` or +xref:qm_virtiofs[dir]) and `<options>` are the device mappings and other +configuration parameters. Note that the options must include a map property with all identifying properties of that hardware, so that it's possible to verify the hardware did -- 2.39.2 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
