I have not attempted to upgrade to DSM 6 yet. I will try to give it a try soon and I will let you know if I have any luck.
Are you running DSM 6 on bare metal or virtualization? I am currently running DSM 5.2 on bare metal but I would like to move to VMWare ESXi when I upgrade to version 6.
Sorry, I have not kept up what's new...what does "jun's mod" mean? Can you please provide a link?
Regarding the RAID settings. I am letting the Dell H700 raid controller handle the raid and I just let the Synology treat it as a single drive. I did this for performance reasons...but I did not do any direct comparison to see if it is actually faster. (Our Xpenology is being used to create a redundant backup our genuine Synology.)
I had read somewhere that it was not a good idea to use multiple individual virtual disks and then combine them into a raid using other software. (Sorry, I can't find the original source where I read this but I think it was in the FreeNAS forums.)