Don't know if this is the best place for this, but here it is:

Machine in question:

PowerMac G5 running 10.5.8, not Server, though the system is being used as backup "server" for multiple users, each with individual accounts. Local office network.

The machine has been substantially modified - OS resides on a SSD all by itself in drive bay A. 4 x 3TB drives occupy drive bay B and a cage mounted between the fans and processors with the other 3, all connected to a iSata PCI card.

These are set up as two RAID sets. These work just fine. When I connect remotely from another machine, they show up and can be mounted on remote machines no problem.

Additionally, there are 4 x 4TB drives in an external enclosure, also arranged as 2 x RAID sets. The sets are all software, not hardware controlled. The enclosure is connected to a PCI port multiplier card via eSATA.

All 4 RAID sets mount just fine on the machine's desktop, 100% access, all working happily. 2 sets show as onboard HDD icons, the two eSata connected sets show up as two drives with the SATA icons, like they should.

PROBLEM - the 2 external sets have suddenly gone funky in that they are no longer seen or mountable from a remote connection. They just dropped off the face of network-earth. I've tinkered with permissions, tried erasing the drives, re-creating the set as the exact same user and conditions that created the originals - NO GO. Nothing has changed to my knowledge, but something must have been tweaked in the OS and I'm at a loss as to where to look. These were all working over the network for pushing 3 months.

Any help, suggestions, etc., would be GREATLY appreciated. Thanks all.