QoS is a means to ensure specific performance levels for applications and workloads. There are two ways to accomplish this:
1. Ability to set limitations to avoid unwanted behavior from non-critical clients/hosts.
2. Ability to set guarantees to ensure service levels for mission-critical clients/hosts.
SANsymphony currently supports only the first method. Although SANsymphony does not provide support for the second method, the platform does offer some options for optimizing performance for selected workloads.
For streaming applications which burst data, it’s best to regulate the data transfer rate (MBps) to minimize their impact. For transaction-oriented applications (OLTP), limiting the IOPs makes most sense. Both parameters may be used simultaneously.
DataCore SANsymphony ensures that high-priority workloads competing for access to storage can meet their service level agreements (SLAs) with predictable I/O performance. QoS Controls regulate the resources consumed by workloads of lower priority. Without QoS Controls, I/O traffic generated by less important applications could monopolize I/O ports and bandwidth, adversely affecting the response and throughput experienced by more critical applications. To minimize contention in multi-tenant environments, the data transfer rate (MBps) and IOPs for less important applications are capped to limits set by the system administrator. QoS Controls enable IT organizations to efficiently manage their shared storage infrastructure using a private cloud model.
More information can be found here: https://docs.datacore.com/SSV-WebHelp/quality_of_service.htm
In order to achieve consistent performance for a workload, a separate Pool can be created where selected vDisks are placed. Alternatively "Performance Classes" can be assigned to differentiate between data placement of multiple workloads.