So can the SSD nodes be mixed with non SSD nodes in a cluster.....I'm guessing no since they use software RAID. They don't do well when mixing drive types.
BTW, clusters up to 10PB in size? Please.....word has it they have severe issues going above 10 nodes in a cluster. They make such a big deal out of one FS but why would you want one FS to be multiple PB in size? With any kind of corruption....guess what? You lose it all and then you have to rebuild or restore. I wonder how long it would take for a consistency check to run on 10PB?