Sequential Data Transfer By Size
Before we dive into trace-based workload testing, let's first look at data transfer performance a couple of different ways. We'll start with data transfer speeds by file size. The larger the blocks, the easier it is for the system to transfer information. Smaller files sizes are bogged down by more metadata, small log-type files that slow the transfer.
Sequential reads show the FreeNAS Mini performing steadily in both of the configurations we're testing. The first test is with SSD cache drives, one for read and one for write. Throughout this review, you can find the ZIL+L2ARC test by looking for the thick red line. The black line shows the FreeNAS Mini without cache. Both the cached and uncached tests use 4x Seagate NAS HDDs with 4TB of capacity each.
Steps were taken to prior to each test to condition the system's flash. iXsystems uses SSDs known to deliver high steady state performance while also recovering from enterprise preconditioning very quickly.
We still haven't found a NAS in this price range that yields a smooth ramp up in sequential writes as the data size grows. As you can see on the chart, systems are optimized at different points. If the iXsystems FreeNAS Mini didn't encounter such a large drop-off with 512KB data, it would have yielded a smoother transition through increasing block sizes.