[pve-devel] [PATCH qemu-server] qcow2: increase cache-size to 1GB

[Fiona Ebner]

Am 14.08.25 um 1:10 PM schrieb DERUMIER, Alexandre via pve-devel:
>>> we also know the image size here, so we could use a capped, derived
>>> value?

Yes, I'd also be in favor of using something calculated from the size.
We could additionally add a drive configuration option to override the
value if we really want to.

>>>
>>> what if the disk is resized? 
> 
> One problem is disk resize, because the cache size can't be increase
> without restart. That's why I think it's better to use a big cache
> size.(It's really a max value) 

But the max value might even be reached for relatively small disks. And
there are users that have a lot of VMs with rather small disks. For
them, the increase in memory consumption would be quite big I suppose!

Resizing a disk in a way that changes the order of magnitude of its size
is rather uncommon, so I don't see an issue of not having a perfect
cache size after such a resize.