Video on demand

Video streaming services, like Video On Demand (VOD), or Video Surveillance, typically require significant amounts of disk storage with predictable latency, high bandwidth and generally using large size I/Os. This differs from low latency optimizations that prioritize absolute lowest latency at the expense of variability and bandwidth. The HPE Smart Array offers several video streaming applicable optimizations. Additional system level optimizations should be evaluated, like I/O prioritization in the BIOS, block layer, and aligning file system allocations to RAID stripes.

This method has the following benefits:

  • Disabling the Elevator Sorting - Reduces maximum latency by processing I/Os in order.

  • Enabling the Degraded Performance Optimization - If using a parity protected RAID level such as RAID 5/50/6/60 optimizes for large block writes while in a degraded mode.

  • Setting the controller Cache Ratio to 100% write - The high stream count creates a very random read I/O profile that will have little benefit of a read ahead cache.

  • Disabling the Controller Monitor and Performance collection - Reduces the latency spikes under consistent heavy I/O load caused by collecting management data.

  • Increasing the Surface Scan Delay to 30 - Minimizes latency impact by controller media surface scans.

  • Using a Rebuild Priority of Medium or MediumHigh - Interleaves rebuild I/Os in a consistent way to have a more predicable latency during RAID rebuilds.

  • Enabling the Flexible Latency Scheduler - Reduces maximum latency for an individual I/O by prioritizing the I/O the longer it takes.