After reading several pages including this great writeup on improving windows storage spaces speeds, I found myself needing to add some SSD journal drives after the fact (after the spaces had already been created). For anyone else looking to do the same, here’s the powershell commands needed to do so.
1. Get the ‘friendly name’ of the disks you’ll be using for journaling, they should be something like ‘PhysicalDisk123’
2. Add the new disks to the storage pool. Under server manager, under file and storage services, under storage pools, right click on the storage pool you want to add journaled disks too and select ‘add physical disk’
3. Set the new disks as journaled in the pool, in powershell enter the below command, replacing the friendlyname with the one you got earlier, do this one disk at a time.
Set-PhysicalDisk –Usage Journal –FriendlyName PhysicalDisk1
4. Set the new disks as SSD if they are not already:
Set-PhysicalDisk –MediaType SSD –FriendlyName PhysicalDisk1
5. Done! A reboot is recommended before using your new journaled disks in the pool.