Yes, you can. I have similar setup, but System is not on a RAID.
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
loop0 7:0 0 93.9M 1 loop /snap/core/9066
loop1 7:1 0 97M 1 loop /snap/core/9289
sda 8:0 0 5.5T 0 disk
`-sda1 8:1 0 5.5T 0 part
`-md0 9:0 0 5.5T 0 raid1
`-raid 253:3 0 5.5T 0 crypt
`-raid--vg-data--lv 253:4 0 5.5T 0 lvm /mnt/raid
sdb 8:16 0 5.5T 0 disk
`-sdb1 8:17 0 5.5T 0 part
`-md0 9:0 0 5.5T 0 raid1
`-raid 253:3 0 5.5T 0 crypt
`-raid--vg-data--lv 253:4 0 5.5T 0 lvm /mnt/raid
sdc 8:32 0 465.8G 0 disk
`-md1 9:1 0 931.3G 0 raid0
`-smallRaid 253:2 0 931.3G 0 crypt
`-vg--smallraid-lv--smallraid 253:5 0 931G 0 lvm /mnt/smallraid
sdd 8:48 0 465.8G 0 disk
`-md1 9:1 0 931.3G 0 raid0
`-smallRaid 253:2 0 931.3G 0 crypt
`-vg--smallraid-lv--smallraid 253:5 0 931G 0 lvm /mnt/smallraid
sde 8:64 0 477G 0 disk
|-sde1 8:65 0 512M 0 part /boot/efi
|-sde2 8:66 0 1G 0 part /boot
`-sde3 8:67 0 475.4G 0 part
|-ubuntu--vg-ubuntu--lv 253:0 0 150G 0 lvm /
`-ubuntu--vg-nextcoud_previews_lv 253:1 0 150G 0 lvm
Here 3 points to check.
- sda and sdb are created on a partitions as RAID 1, here is data folder of Nextcloud.
- sdc and sdd are created on a RAW as RAID 0 (just summarize size of disks, no relevant data here)
- and I have 1 partition for the nextcloud previews folder moved to the SSD (sde), so that it is increased access performance on a random access.