It had hot-swap SATA disks (up to 512GB disks initially!) and was actually pretty cool and forward thinking
https://web.archive.org/web/20061128164442/http://www.sun.co...
At the time I advised my company to skip the storage servers (which were overdesigned IMHO, but were unquestionably stout hardware) but that ZFS was an interesting filesystem to explore.
Unfortunately for them, no one knew how to administrate Solaris, so they... installed Windows. No idea if they actually succeeded in doing anything useful with the systems.
Hardware was great, but no linux/zfs support meant we didn’t stick with it.
A couple of years later we had standardised on supermicros with a similar density and ran linux on them.
Sun lost a fair amount of money from us (7 figures) by choosing not to embrace linux.
They were incredibly cool for the time.
> things that were designed with vertical hard drives dropped down from a top-opening lid to achieve even higher density.
the backblaze storage pod system and some 3rd party derived designs have the SATA/power ports on PCBs facing upwards, mounted at bottom interior of rack chassis, and 3.5" HDDs mounted vertically down into the system.
What wasn't really a thing was servers with hotswap HDD trays on both ends (like the supermicros) and things that were designed with vertical hard drives dropped down from a top-opening lid to achieve even higher density.