Here is what one person said:
“Whichever drive (SSD or HDD) that you initially setup your QNAP with will house not only your apps, but QNAP configuration itself, etc. If that drive fails, you not only lose your app, but your QTS installation. Essentially you are rebuilding your NAS (minus any data stored on say a separate HDD).”
I understand I will lose apps if I delete my system volume containing the apps, but why would I lose QNAP configuration and the QNAP installation? aren’t those stored on a ROM chip or something? Right now i’m experimenting with my TS-653D and I’ve deleted my system volume a few times and I only lose the applications (I didn’t put data on it yet). the QTS is still there obviously. in fact if you boot the NAS without any disks at all, you can still access the QTS. so am I not getting something here?
Qnap just like Synology have its internal flash memory chip. This is where default DSM and QTS is stored to my understanding. Once the disks are introduced, all settings must be saved on disks too. So I presume settings do exist in both places.
Qnap manual says that after migrating disks from an old NAS to a new NAS you need to update the firmware. All data and settings are migrated. Here is the warning message mentioning the flash storage of firmware.
Here is some more info how to do it: https://docs.qnap.com/nas/4.3/cat1/en/index.html?system_migration.htm
I just talked to Qnap and this is what they said:
In answer to your question, in QTS, every drive has the OS. Every drive has the config file. So even if the drive with the system volume were to fail, you would still have QTS and you would still have your settings.