Why do SSDs benefit from a scheduler like noop? Solution The default I/O scheduler for Linux is Completely Fair Queueing, and is a virtuous all-round scheduler. Mutual wisdom holds that CFQ is needless or sub-optimal on systems that disrupt the normal assumptions, such as hardware RAID cards equipped by a write-cache, or SSDs. In these cases, the noop scheduler is recommended. The noop scheduler does nothing overlooking the chance to optimize our disk admissions. All our VPS hypervisors take hardware RAID cards with a write-cache, consequently we set out to see if there were any improvements to be had from changing to the noop scheduler. Seeing by way of we’d required it to roll out any large-scale alterations, we utilized Puppet to help us discover some appropriate test subjects. By loading a custom Feature fact into our manifests, we could clutch all the PCI IDs for RAID cards and see what representations were installed in dissimilar servers. every smart RAID cards had the similar PCI ID, which parallels to the PERC H700 and H800 hardware..