What Does a Node Server Do?

[ere109]

I've currently got a CSE-836 chassis and need to add more hot swap drive space. Barebones 836 chassis are $350 plus, but for $250 there's a Supermicro 3U two node server with 16 hot swap bays. Please educate me.
Is a node setup too complicated for a standard home user, or is there some terrific advantage? How do the nodes operate? Do they run as two separate devices - two servers in one box - or do they operate in a "mirror" capacity like a mirrored drive? How would a TrueNAS setup look on a two node server? It appears that both nodes have access to all 16 drives, and accessing the drives is my main goal. This would clearly double power usage.
I've been happily running my single X9 board for five years, and I'm really just trying to add extra disk storage, but this two node unit is cheaper than a bare 836. Is this a "fun" new path to take and learn from, or just a giant ball of twine?

Thanks
The ebay listing:

Pardon Our Interruption...

 

[sretalla]

Conceptually, if you're looking for a 2-node high availability system, you need to use TrueNAS Enterprise (i.e. buy iX hardware and support).

The free versions (CORE and SCALE) don't include essential functionality for the high availability features needed to make sense out of it.

SCALE can potentially make some use of a milti-node cluster (minimum 3 nodes) for SMB and gluster replication, maybe apps coming soon too, but that hardware doesn't really get you anywhere with that (only 2 nodes).

Basically, you get 2 servers crammed into one chassis with some or no components in common (most likely storage could be shared, for example... but would not be helpful to TrueNAS... applies to other OS clustering scenarios).

 

[danb35]

Basically, you get 2 servers crammed into one chassis with some or no components in common (most likely storage could be shared, for example

In the case of my Dell units (C6100 and C6220), not even that--the only things in common are power and the chassis itself. Still a handy way to get lots of cycles into a fairly small space. Not the greatest for storage, though.