I'm testing disk performance in Windows and after reading the Windows best practices and performance tweaks articles, I didn't find much said about how disk cache setting inside the guest relates to the vm settings in Proxmox.
If running a production workload inside the vm it feels wise to set the disk removal policy to 'quick removal' for data integrity. Especially if running any kind of database application. This also seems to have the most performance impact compared to any disk cache setting in the vm configuration. There isn't much difference between 'none' and 'directsync' or even 'writeback' when using 'quick removal' policy in Windows. This is with ZFS backed SSD storage.
What settings are people using? The default 'better performance' with 'directsync' gives much better performance but feels quite unsafe and probably shouldn't be used.
If running a production workload inside the vm it feels wise to set the disk removal policy to 'quick removal' for data integrity. Especially if running any kind of database application. This also seems to have the most performance impact compared to any disk cache setting in the vm configuration. There isn't much difference between 'none' and 'directsync' or even 'writeback' when using 'quick removal' policy in Windows. This is with ZFS backed SSD storage.
What settings are people using? The default 'better performance' with 'directsync' gives much better performance but feels quite unsafe and probably shouldn't be used.