Howto verify if Storage Spaces uses Journal disks
Solution 1:
Get-PhysicalDisk PowerShell cmdlet is your best friend. Loop over all disks in your system checking "-Usage" parameter. For journal disks it will be "Journal" (surprise!). If there are no "Journal" disks detected your pool isn't using journalling disks.
https://docs.microsoft.com/en-us/powershell/module/storage/get-physicaldisk?view=win10-ps
Solution 2:
I use this to verify Journal on my parity space for my F: drive (serialnumber / uniqueid omitted here, only 26 GB at the end of the the SSD are used for the Journal, the rest is a normal drive):
PS C:\> Get-StoragePool -FriendlyName Pool-F | Get-PhysicalDisk | ft FriendlyName,MediaType,HealthStatus,canpool,CannotPoolReason,size,uniqueid,SerialNumber,Usage
FriendlyName MediaType HealthStatus canpool CannotPoolReason size Usage
------------ --------- ------------ ------- ---------------- ---- -----
WDC WD30EFRX-68AX9N0 HDD Healthy False In a Pool 3000592982016 Auto-Select
WDC WD30EFRX-68AX9N0 HDD Healthy False In a Pool 3000592982016 Auto-Select
Samsung SSD 860 EVO 4TB SSD Healthy False In a Pool 4000787030016 Journal
ST33000651AS HDD Healthy False In a Pool 3000592982016 Auto-Select