The DS1817+ is a another great NAS from Synology as you can enable SSD cache without sacrificing any of the drive bays.
It is a good choice if you are looking to upgrade from a 4 or 5 bays NAS. However, the benefits might be marginal if you are upgrading from the DS1815+ unless you are looking enabling SSD cache via the M2D17 dual SSD adapter.
The reading and writing performance definitely improved when the SSD cache is enabled using the Samsung 850 EVO and Western Digital Blue M.2 SSDs. The network transfer should also improve correspondingly.
For those who are running virtual machines via the Synology Virtual Machine Manager, you will be pleasantly surprised by the performance boost that SSD read-write cache will bring. In our benchmark, read and write latencies reduced as much as 400% and IOPS improved by almost the same factor.
Lastly, my advice to potential M2D17 adopters is to use similar performance SSDs for read-write cache. I suspect the latency spikes observed while benchmarking the performance of read-write are due to the difference in the individual SSDs’ performance. As mentioned earlier, the spikes are statistical outliers as the median and standard deviations looks pretty ok.