I'm retired and in purely domestic environment. I have a couple of computers - iMac & MacBook Pro - plus a phone and a tablet. I had a couple of external USB drives off the back of the iMac to hold a) my Lightroom images files - about 700Gb - and b) Time Machine backups from the iMac, including the LR images from the first drive. Wanting to make the LR images visible across my home network (which is part Cat5 ethernet, part WiFi) I started looking for a NAS. Given my budget I settled on a DS220j. I know it's not as capable as a DS220+ but given my budget & use case, it seemed more appropriate. And indeed, mostly it is. It's installed, with two 4TB drives configured as a mirrored pair (SHA?). The LR images are stored in one shared folder, which is itself being backed up to one of the old USB drives using Hyper Backup; and Time Machine is now backing up the iMac, minus the LR images, to a second shared folder. So I'm pretty happy. But there were some unexpected things. I had planned on installing 2 Volumes within the storage pool and separating the two data stores in that way (a shared folder in each volume). However, the software did not give me the choice of creating multiple volumes during setup - at the end of the setup I was presented with the single Storage Pool and a single EXT4 Volume occupying the whole storage pool. I also quickly learned that a volume cannot be reduced in size! - only increased. So I trashed the first setup and went through it again, with the same result. In many ways this doesn't really matter except for one thing: the Time Machine 'quota' system requires that the file system be btrfs, it seems, not EXT4. Therefore I can't automatically limit the eventual size of the Time Machine backup file, I will have to keep it under observation and eventually trash it (or move it to a safe place temporarily) and then start again with a fresh Time Machine backup. Not a biggie, however. I think I'm just curious as to why I wasn't presented with the options to create more than one Volume. Is it a limitation of a two-disk setup? Or could it be specific to the DS220j, which is after all aimed squarely at NAS-beginners? I can see that making things easy by removing setup complexities could be justified in that situation. Finally, I'll add that so far I haven't found the limited resources of the 220j to be a problem. I'm pretty much the only user, so that's not an issue. I was watching the CPU and memory meters while a) copying the LR image files onto the NAS; b) while Hyper Backup was running and creating the backup on the external USB drive; and c) while Time Machine on the iMac was creating the initial backup file on the NAS, and in all cases the CPU stayed at around 25%/30%, while the memory meter never went above 60%. So in my situation, the available resources seem to be good enough.
I am impressed with your IT skill at respectful age.
DS220j just like all J series are very simple models made for first time users or simple backups. They are limited to EXT4 because they could not run snapshots that require BTRFS.
But there is no restriction on multiple volumes though.
Here is what they say:
Multiple volumes can be created in a storage pool if it supports multiple volumes. If your RAID type is RAID 0/1/5/6/10, you can create multiple volumes to avoid the 16 TB or 108 TB limitations; however, the maximum size of each volume still needs to be smaller than 16 TB or 108 TB, respectively.
To check whether a storage pool supports multiple volumes and to create multiple volumes, please do the following:
I remember when the volume was created without a storage pool, then there were few limitations. May this is it: Storage Manager > Storage Pool
I hope this helps.