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diff --git a/proxmox/disk-performance.md b/proxmox/disk-performance.md new file mode 100644 index 0000000..21d3a53 --- /dev/null +++ b/proxmox/disk-performance.md @@ -0,0 +1,31 @@ +# Disk performance + +Taken from https://forum.proxmox.com/threads/virtio-scsi-vs-virtio-scsi-single.28426/ + +> VirtIO SCSI vs VirtIO SCSI Single boils down to a simple architectural choice that has real performance implications: +> +> Standard VirtIO SCSI uses one controller that handles up to 16 disks, while Single dedicates one controller per disk. This matters most when using IOThreads (iothread=1), because threads work at the controller level. +> +> When using IOThreads, Single shows significantly better performance (often 30-50% improvement) because each disk gets its own dedicated processing thread. Without IOThreads, the performance difference is minimal (typically less than 5%). +> +> So the choice is straightforward: +> +> > Want maximum disk performance? Use Single + iothread=1 +> > Managing lots of disks with limited resources? Standard might be better to avoid thread overhead +> > From the VM's perspective, they work exactly the same +> +> This explains why benchmarks consistently show better I/O performance with Single + iothread=1, while keeping the underlying architectural differences clear. + +Which results in the following packer configuration : + +```hcl + ... + # VM Hard Disk Settings + scsi_controller = "virtio-scsi-single" + + disks { + ... + io_thread = true + } + ... +``` |