Introduction

VM I/O Throttling, to set the maximum disk I/O rate of VMs.

Purpose

Virtual machines are running on the same storage device (local storage or share strage). Because of the rate limitation of device (such as iops), if one VM has large disk operation, it may affect the disk performance of other VMs running on the same storage device.
It is neccesary to set the maximum rate and limit the disk I/O of VMs.

Target Branch

4.2

Feature Specifications

• set the maximum rate of VMs
• change the maximum rate of VMs

Use cases

TBD

Architecture and Design description

• change service_offering table in cloud database.
• change kvm/LibvirtComputingResource to support IO Throttling (need the support from libvirt-0...jar)
• change APIs
• change the CloudStack UI

Web Services APIs

createServiceOffering: Creates a service offering.
updateServiceOffering: Updates a service offering.

UI flow

add "Disk I/O Rate" in "Add Disk Offering"
add "Disk I/O Rate" in the detail page of unique disk offering.

References

• Features/DiskIOLimits : http://wiki.qemu.org/Features/DiskIOLimits
• Testcase Virtualization IO Throttling: https://fedoraproject.org/wiki/QA:Testcase_Virtualization_IO_Throttling
• I/O throttling is experimentally supported from QEMU 1.1 : http://wiki.qemu.org/ChangeLog/1.1#Block_devices

Appendix

Appendix A:

Appendix B: