Can't access files stored on Centera by FMA

Today, all the files archived to our Centera have become unavailable. You can view the stubs, but trying to read or write to the files comes up with the error "Cannot read from the source file or disk". Yesterday everything was working fine.

We store files from CIFS shares on a NS120 using the FMA appliance. Our archival settings are very simple, anything over 120 days old gets archived.

I've checked a few things, all the NICS in the cluster are active and set to the correct speed/duplex (on the devices and the switch). All the nodes (4 of them) are online and not locked.

There are no capacity issues, the pools are at most 50% full. The entire cluster is only around 40% full.

No devices are showing any errors, there are no warnings and the CLI doesn't flag anything in the health check or summary etc.

I've logged a support request but thought I'd check here as well on the off chance someone has experienced this before and has a quick fix!