You can install it on a hardware RAID, from the Quick Guide:

Only RAID controllers with multiple LUN support can be used. Please create a small 2GB logical
unit for DSS V6. Running DSS V6 installer you will need to select this 2GB logical unit as the boot
media. On the rest of RAID space please create second LUN for the user data. The following RAID
controllers are supported as a bootable media: MegaRAID, 3ware, Adaptec, ICPvortex, Areca
(more RAID controllers will be added in next release).
I guess you could use linux software raid create but would require customizing the boot process, scrips and configuration files, etc... I once thought about doing it (does not seem that difficult if you know what you are doing) but I realized it would be a nightmare to support as updates could potentially mess with the custom boot, etc. I would not recommend it...