Does each disk appear the same when selected in Disk Utility? If so, it looks very much like a FreeNAS pool, especially with the 2GB swap partitions. If not, post a screenshot for each disk.
I suggest you try booting into FreeNAS, opening the Shell and posting the output from zpool import. I'm going to bed now but someone else will surely respond. If it shows an importable pool, try to resist the urge to actually import it right away, unless guided by an experienced forum member. If you can't resist, at least start by importing it read-only.
I'll check back tomorrow.
EDIT: I see now that the PDF shows all five disks with partitions consistent with a FreeNAS pool.