[TUTORIAL] Storage Controller Efficiency Data for Bandwidth-Constrained Workloads on Shared iSCSI Storage

[bbgeek17]

Greetings everyone,

Good news! We've managed to carve out some time to compile the latest data set for our ongoing exploration of Windows 2022 server on Proxmox.

Part 3: Computational Efficiency of Storage Controller Configurations under Constrained Bandwidth Workloads

Expanding upon the groundwork laid in Part 1, our third installment goes deeper into the computational efficiency of all storage controller configurations. While Part 2 scrutinized efficiency under an IOPS-based workload, Part 3 shifts its focus to efficiency under bandwidth-constrained workloads. To clarify, Part 2 assessed efficiency with a larger number of small-sized I/O requests, while Part 3 analyzes the efficiency of larger-sized I/O requests that are fewer in number. You can find Part 3 here:

• https://kb.blockbridge.com/technote/proxmox-optimizing-windows-server/part-3.html

TLDR: Here are the key takeaways of the bandwidth-constrained efficiency study in part 3:

• The virtio-scsi controller with aio=native achieves the best overall efficiency score.
• aio=native was the most efficient aio mode for each controller type; aio=threads was the least efficient.
• With aio=native, virtio-scsi was 4% more CPU intensive than virtio-blk but generates 25% fewer context switches.
• With virtio-scsi and aio=native, an iothread introduces a small CPU efficiency overhead of 1.5%, but reduces context switches by 5%
• vmware-pvscsi was the most efficient storage controller option (for bandwidth) natively supported by Windows Server 2022.
• vmware-pvscsi with aio=native consumes 60% less CPU and generates 40% fewer context switches than vmware-pvscsi with aio=iouring.
• The SATA and IDE controllers achieve the worst efficiency scores primarily due to high context switching rates.

We're hoping to finish up part 4 in a week or two. If you are looking for the previous parts, you can find them here:

Part 1: https://kb.blockbridge.com/technote/proxmox-optimizing-windows-server/part-1.html
Part 2: https://kb.blockbridge.com/technote/proxmox-optimizing-windows-server/part-2.html

If you find this helpful, please let me know. Questions, comments, and corrections are always welcome.

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox