Hello!teckel wrote: ↑Sat May 20, 2017 12:37 am Using two SSDs for read-write cache acceleration is the way to go. This creates a RAID1 cache array. I have mine setup to cache all, with a bypass block size of none. I purchased two Samsung 850 EVO 250GB drives for the task. I use my NAS mainly for entertainment, file sharing, virtualization, and security camera.
Since installing the SSD cache acceleration, the NAS is super quiet. Before, it had to constantly write security camera streams, read/write file shares, and I almost always have at least one virtualization running. Now it seems to read/write mostly to/from the SSD cache. Also, virtualization is MUCH faster. Boot times and running it in general is SUPER snappy.
One would probably never notice a speed difference for watching videos, file sharing, or the security cameras. But, the reduced reading/writing to the platter drives is still a benefit from reduced noise (and probably wear and tear on the platter drives too). I can imagine if I download a video and then watch it within a day (a very common occurrence) the file would be mostly (or all) in the SSD cache as it would take a while to flush through 250GB of cache.
It would be nice if QNAP provided a little more details on what was going on. The Hit Rate History graph is nice, but showing more detail would be welcomed. I think it would help justify the SSD cache to some. Also, I don't get any kind of slow transfer rates that some people have experienced once the cache is 100% allocated. Mine took a couple days to become 100% allocated and I still see a performance gain without any slow-downs.
Tim
Late to the party here. Thank you for this reply as I am facing a similar issue.
I have a TS-963X and all 9 bays are SSDs. I set one as the cache drive and after 1 year of being configured this way, I do not believe I have noticed any performance enhancement. So I am considering ditching the Cache drive to increase the size of the array.
Your post suggests that the real benefit of cache acceleration is to temporarily store data on the SSDs that would otherwise be pulled (slower) from spinning disks. So, if all the systems were already SSD, then there would be no real benefit- right?
Thanks!
Bob