Sometimes adding spindles is not enough to resolve a storage performance problem. Today – with high performing SSD disks – it’s getting more and more important to build a good understanding on the architecture of a storage arrays. Eventually this will help you to determine the caveats and will make you pose the good questions to get the maximum performance out of your IT infrastructure.
Some time ago, I got confronted with a storage performance problem. The disk array installed in an appliance was able to move 600GB/hour in 60% write and 40% read. When contacting the vendor, they advised me to install more spindles as this will distribute the load and I would gain performance. Upon validation of the system – storage array controller – specifications, it became clear this would not resolve the situation as the storage controller was already at maximum performance! This is a perfect example of a CPU-bounded system.
The goal of this blogpost is to define the difference between CPU-bound and Disk-bound. Continue reading