NAS Noob Question: Synology DS218j add new storage pool


Limp Gawd
Aug 15, 2004
Disclaimer: I know jack about an NAS. I bought a Synology DS218j so I could have an always-on network storage device to stream movie and TV show files without having my PC on 24-hours a day.

The Western Digital white 10 TB drive in my DS218j is getting close to capacity, so I bought and added a second identical drive. But after Storage Manager took close to 24 hours to “add it to the storage pool” whatever that means, it still only showed 9 TB of space total.

Apparently I created a RAID1 array with the new drive as a redundancy and no additional storage, which does me no good.

I want to split my data, which is all currently on the one 10tb drive streaming to Plex, between the current one and the new 10tb, with movies on one drive, TV shows on another. I'm not too concerned with data backup at this time because I back it up to internal hard drives on my PC periodically and I'm investigating inexpensive automated cloud backup.

I've been told that I should a new storage pool for the 2nd 10tb drive. Is that correct? If so, how do I go about that with Synology's Storage Manager; it's not obvious to me. If you don't want to type it out, just a link would be fine.

And if a new storage pool doesn't fit my needs, what would you suggest?

Thanks so much for your help!
I'm going to guess you are using SHR "RAID" as it is the default Synology option. You can only add redundancy on a 2 bay NAS when using SHR per

"For an SHR volume containing one drive, storage capacity will only be expanded when two or more drives are added."

I've never tried having more than one array on a Synology. If it supports it you may be able to create a new JBOD array with the new drive and make another 10tb share. If you need a 20tb share you are going to have to backup the data, re-configure the NAS as a JBOD with both drives, then restore data.
I'm sorry, but that's over my head. Like I said: NAS noob.

Alright, so below is a screenshot of Storage Manager. Should I remove the new drive, then reinsert it a while later and configure it as a new storage pool? If not, how do I go about having two volumes in the same 2-bay NAS, each with 9+ tb or available space?

I would prefer not to have to copy the whole 7+ tb off of the NAS, do whatever I need, and then copy it all back on. That's going to take like 2 days.


You cannot do it via DSM to go from an SHR mirror to SHR span in a 2 bay device without moving the data off and recreating the array. You could, theoretically (Though I would NOT recommend this) degrade the array by pulling 1 drive, format the second out of the synology, kill the rebuild process upon reinsertion from the command line and setup the new drive as a single JBOD drive. That would be an incredibly risky maneuver and leave your array in a precarious state. Backup your data, recreate your array and move it back
I would prefer not to have to copy the whole 7+ tb off of the NAS, do whatever I need, and then copy it all back on. That's going to take like 2 days.
The problem with this sort of thing is that shortcuts usually end up taking longer down the road.