Comment by jabl

I work in HPC and at some point we had a dozen or so racks with blade systems in our cluster. IIRC it was HP c7000 blade enclosures, 16 nodes in a 10U chassis. We had 4 such chassis in each rack. So reasonably dense, and there was a bit less cabling compared to individual servers.

OTOH, much of the cost saving of less cabling was eaten up by the vendor charging higher prices for equipment like HCA's or switches compatible with the blade enclosure. And unless you went for a fully non-blocking IB fabric there were a bunch of unused IB switch ports.

Also, while the blade enclosure had this fancy web GUI for management, at scale we had built our OOB management automation around IPMI anyway, so this wasn't a feature worth much for us. If anything it was a bit of a chore, as in the cases when we needed to do something which IPMI wasn't capable of, there was an extra step of figuring out the node->chassis mapping to know which chassis to connect to, and then figuring out which blade in the chassis corresponded to the node in question.

For the next generation we got these "twin" systems manufactures had started coming out with, with 4 nodes in a 2U chassis. A bit more cabling than the blade systems, but in the end it was somewhat cheaper.