Virtualization Technology News and Information
VMware Storage IO Control - SIOC vSphere 4.1 Feature

VMware administrators are well aware of VMware DRS and it’s usage in measuring and reacting to CPU and Memory contention.  With the next version of VMware vSphere, 4.1, VMware will introduce Storage I/O Control (SIOC), which is in essence a very similar feature but for I/O, utilizing I/O latency as the measure and device queue management as the contention control.  SIOC provides the capability to define quality of service prioritization for the I/O activity on a single host or cluster of hosts.  I/O resource allocation will be controlled through the use of share values and limits assigned to the VM, much in the same way as the current DRS is for memory.  And this prioritization can be enabled and disabled on specific datastores. 

According to VMware's Duncan Epping of Yellow-Bricks fame, there are a couple of things to keep in mind though:

  • SIOC is enabled per datastore
  • SIOC only applies to disk shares when a certain threshold (Device Latency, most likely 30ms) has been reached.
    • The latency value will be configurable but it is not recommended for now
  • SIOC carves out the array queue, this enables a faster response for VMs doing for instance sequential IOs
  • SIOC will enforce limits in terms of IOPS when specified on the VM level
  • No reservation setting for now…

For some entertainment and information, check out this SIOC video.  It is definitely worth watching!


Published Friday, June 18, 2010 5:52 AM by David Marshall
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