Cache has limited uses (short write boosts or constantly reoccurring read boosts) … most people do not make use of these patterns … so here the cache does nothing besides slowing down
See this old multi page topic that is still current
https://forum.qnap.com/viewtopic.php?t=124852
So purchasing the flash drive was a waste of money then? UGH! I was trying to speed up performance.
Oh it’s just one drive … even worse, single drive cache is extremely dangerous as you lose access to all data upon failure. NEVER EVER run cache on just a single drive.
OK. Figured that SSD was pretty reliable. OK. Can I use this flash drive for anything else other than Cache then?
A RAID1 SSD array (again, never on a single drive) is a very good idea for the system volume, it would be the default storage for installed apps, so apps that use databases or metadata would load MUCH faster than from HDD.
OK. So I could use the M.2 SSD as another drive but I should get a second one.
So looking at some docs in the knowledge base, if I want to reinstall the OS, I need to completely re-initialize the NAS - ie: Make sure all my data is backed up and then wipe it and start over then restore the data.
Is there any way to reinstall the OS w/o losing everything first?
Number one rule is to always have backups … if you have to think about backups now … you dodged a VERY expensive bullet down the line (when your system/RAID failed or you/someone deleted your files).
Oh yeah, I have backups and in multiple places as well both locally and in multiple cloud locations. It’s just a ton of work!
Now is there anything special about the RAM needed in the NAS? QNAP seems to say that there is but that seems like a poor design if it’s so finicky.
Check the topics in the old forum for RAM advice
QNAP units are picky but you can get 3rd party modules that work.
OK. I will take a look.
If you set up the system on the SSD’s in RAID1 then couldn’t you just leave all the data as-is on the other RAID drives? Or would the new OS install basically require that all the RAID arrays be recreated which would wipe out your data anyhow.
I’m trying to just figure out how to save some time here. 
If I am going through this, I may just want to invest in a couple of additional 10 TB drives and expand my first storage volume…
Your current HDD array will be the system volume, you want the new system volume to be on SSD, that’s why
Also your busted OS with the slow loading virtual switch is still on the HDD array
Got it! I have the second SSD drive on order from Amazon - will be here in the morning!
We will see how long the cache flushing takes. It’s just at 7% right now…
One more question.
Should I install QTS or QuTSHero for the OS? I don’t think I need QuTSHero but the immutable storage option is nice.
QuTS has some quirks when it comes to adding disks later to existing pools (depending what z level your chose), otherwise I think ZFS is pretty good. I use it on my h1288X and it works great.
Does everything have to be immutable or can you choose what to keep permanently.
And all the same apps and all with QuTSHero yes?
See here
Apps are pretty much the same, the OS is almost the same between QTS and QuTS (the OS is also still installed on md9 and md13 in ext partitions, even on QuTS)
What did you use to give you these graphs?
