cdsfs1 locked up again Wed morning, with the same symptoms it has had in the past when the RAID controller hangs.  I reviewed the logs, but they did not provide any additional clues (other than what we know from previous cases).  I've verified that we are running the current tools versions for the card in the OS.

I've upgraded the firmware to the latest release, 4.10.00.027, as the installed version was rather old.  We will see if this improves things; it may be that we picked up an upstream kernel driver update when upgrading the OS that required the firmware to be upgraded, and we've missed this fact.  That may explain why cdsfs1 has historically been 'more unreliable', because we've updated the OS on cdsfs1 much earlier, and more often.  But this is largely speculation.  We will just have to wait to see if this improves things.