Hi Lusteri, i'm looking to SSD caching too. Now i have my OMV 4.x on an old but robust HP DC77000 MT with 6GB of RAM, a 2.5" 160GB system disk, a RAID1 with 2X2TB, and i want to update it to 5.x.
I have a unused 240GB SSD, 1 SATA3 pci-e controller (the HP is SATA2), and 1 Gigabit NIC. I'm thinking to put them in my existing NAS, and the main goal is to expedite my customers backups as well the restore of them. With the SSD Caching & dual Gigabit i think and i hope to bring my actual transfer rate from 120MB/s max to 200/240..
All in all, if it doesn't work well i will have a faster reboot (for the few cases of rebooting neeeded, now the cycle neeeds 2 minutes...), and some SSD space to fiddle with
Tomorrow i'll start, wish me luck