[pve-devel] [PATCH docs 1/4] qm: hard disk controllers: reword and update section

Fiona Ebner f.ebner at proxmox.com
Fri Feb 17 17:08:33 CET 2023

Most importantly, mention that VirtIO SCSI single in combination with
IO thread is the new recommendation and default. The controller type
used for the QEMU commandline is still the same (but one for each
disk), so information about when OSes started supporting it should be

Signed-off-by: Fiona Ebner <f.ebner at proxmox.com>
 qm.adoc | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/qm.adoc b/qm.adoc
index 8a49283..629e913 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -169,16 +169,15 @@ connected. You can connect up to 6 devices on this controller.
 hardware, and can connect up to 14 storage devices. {pve} emulates by default a
 LSI 53C895A controller.
-A SCSI controller of type _VirtIO SCSI_ is the recommended setting if you aim for
-performance and is automatically selected for newly created Linux VMs since
-{pve} 4.3. Linux distributions have support for this controller since 2012, and
-FreeBSD since 2014. For Windows OSes, you need to provide an extra iso
-containing the drivers during the installation.
+A SCSI controller of type _VirtIO SCSI single_ and enabling the
+xref:qm_hard_disk_iothread[IO Thread] setting for the attached disks is
+recommended if you aim for performance. This is the default for newly created
+Linux VMs since {pve} 7.3. Each disk will have its own _VirtIO SCSI_ controller,
+and QEMU will handle the disks IO in a dedicated thread. Linux distributions
+have support for this controller since 2012, and FreeBSD since 2014. For Windows
+OSes, you need to provide an extra ISO containing the drivers during the
 // https://pve.proxmox.com/wiki/Paravirtualized_Block_Drivers_for_Windows#During_windows_installation.
-If you aim at maximum performance, you can select a SCSI controller of type
-_VirtIO SCSI single_ which will allow you to select the *IO Thread* option.
-When selecting _VirtIO SCSI single_ QEMU will create a new controller for
-each disk, instead of adding all disks to the same controller.
 * The *VirtIO Block* controller, often just called VirtIO or virtio-blk,
 is an older type of paravirtualized controller. It has been superseded by the

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