Ok
On another website I found an intresting guide which recommends to keep the data drive separated from OS drive (if maybe there are problems with OS you could detach data and play around to make Xpenology working again and then attach data disk back) and to have synoboot loader as USB emulated drive instead of SATA drive. What about that? I'm using it as USB emulated drive, but the thing I notice is that I could potentially "safely remove" it from DSM which it's a thing I don't like, and it's shared as usbdrive1-1 in my network locations. The pro is that I think the loader is made to run from USB, so it's running "as designed". What do you (or anybody else) think about it running from HDD or USB? What are the pros and the cons?