Re: [PATCH pve-docs 3/3] partially fix #1989: qm: document qcow2 cache size config

[Dominik Csapak <d.csapak@proxmox.com>]

On 6/5/26 5:35 PM, Erik Fastermann wrote:
> Add a new subsection to document the new qcow2 cache config options.
> 
> Signed-off-by: Erik Fastermann <e.fastermann@proxmox.com>
> ---
>   qm.adoc | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/qm.adoc b/qm.adoc
> index e6b7918..2f1e7d4 100644
> --- a/qm.adoc
> +++ b/qm.adoc
> @@ -341,6 +341,16 @@ underlying storage. Another benefit is reduced latency (hangs) in the guest for
>   very I/O-intensive host workloads, since neither the main thread nor a vCPU
>   thread can be blocked by disk I/O.
>   
> +[[qm_hard_disk_qcow2_cache]]
> +Cache Size (qcow2)
> +^^^^^^^^^^^^^^^^^^
> +Fine-tuning the qcow2 L2/refcount cache behavior can provide significant
> +performance gains. See the
> +https://gitlab.com/qemu-project/qemu/-/blob/master/docs/qcow2-cache.txt[QEMU documentation]
> +for a detailed explanation of these options. You can either configure the cache
> +size directly or let Proxmox VE automatically choose a cache size based on the
> +disk image size. All other options can be managed with the API.
> +

i would have liked a short explanation how the auto-sizing algorithm
works. I guess as an admin this would be the first thing i'd ask
if i see an 'auto' option (e.g. to gauge the memory requirements
for my vms).


>   [[qm_cpu]]
>   CPU
>   ~~~