How can you optimize virtual machine disk I/O throttling?

1 Assess your disk I/O needs

The first step to optimize disk I/O throttling is to assess your disk I/O needs for each VM. This depends on the type and workload of the operating system and applications that you run on the VM, as well as the configuration and capacity of the host system's disk storage. You can use various tools, such as iostat, vmstat, or sar, to monitor and measure the disk I/O activity and performance of your VMs. You should also consider the expected peak and average disk I/O demand, as well as the potential impact of disk I/O bottlenecks on your VMs.

2 Choose the right disk type and format

The second step to optimize disk I/O throttling is to choose the right disk type and format for your VMs. There are different types of virtual disks, such as raw, qcow2, vmdk, or vhd, that have different features and advantages. For example, raw disks offer the best performance and compatibility, but they consume the full allocated disk space regardless of the actual usage. Qcow2 disks support features such as compression, encryption, and snapshots, but they have higher overhead and complexity. You should also choose the right disk format, such as ext4, xfs, or ntfs, that suits your operating system and applications.

3 Adjust the disk I/O limits and shares

The third step to optimize disk I/O throttling is to adjust the disk I/O limits and shares for your VMs. Disk I/O limits are the maximum amount of disk I/O operations that a VM can perform per second or per millisecond. Disk I/O shares are the relative priority or weight that a VM has when competing for disk I/O resources with other VMs. You can use various commands or tools, such as virsh, qemu-img, or vmware-vdiskmanager, to set or modify the disk I/O limits and shares for your VMs. You should balance the disk I/O limits and shares according to your disk I/O needs and the host system's capacity.

4 Optimize the disk I/O performance

The fourth step to optimize disk I/O throttling is to optimize the disk I/O performance for your VMs. This involves tuning various parameters and settings that affect the disk I/O efficiency and speed, such as the cache mode, the scheduler, the alignment, the fragmentation, and the compression. You can use various commands or tools, such as hdparm, tune2fs, or btrfs, to optimize the disk I/O performance for your VMs. You should also monitor and test the disk I/O performance regularly, and make adjustments as needed.

5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?