VMware Storage I/O Control

VMware Storage I/O Control

    VMware introduced a feature called Storage I/O control (SIOC), which enables you to perform attenuation of the I/O for each virtual disk you choose. The SIOC feature in vSphere 5.x is disabled by default. Storage I/O Control provides I/O prioritization of virtual machines running on a cluster of vSphere hosts that access a shared storage pool.

    It extends the familiar constructs of shares and limits, which have existed for CPU and memory, to address storage use through a dynamic allocation of I/O queue slots across a cluster of vSphere hosts. When a certain latency threshold is exceeded for a given block-based storage device, SIOC balances the available queue slots across a collection of vSphere hosts; this aligns the importance of certain workloads with the distribution of available throughput.

   This balancing can reduce the I/O queue slots given to virtual machines that have a low number of shares, to provide more I/O queue slots to a virtual machine with a higher number of shares. SIOC reduces I/O activity for certain virtual machines so that other virtual machines receive better I/O throughput and an improved service level.

   For more information, refer to the technical white paper: vmware.com/files/pdf/techpaper/VMW-Whats-New-vSphere41-Storage.pdf VMware Storage I/O Control and the HP MSA 2040 Storage system combine to provide a more performance-optimized storage solution. Enabling Storage I/O control is a simple process. More important is an understanding of the virtual machine environment with regard to the I/O demand being placed on the array. Storage I/O control is not dependent on the array; it is more of a VMware vSphere infrastructure solution.