Depends on your host adapter.
There are only two possibilities:
1. The LUN is corrupted.
2. The LUN was initialized outside the adapter being used to connect to it and the current adapter is more limited.
In either case, you may lose data... I would suspect the first case if the filesystem on the LUN is valid. That would mean that the LUN configuration got corrupted somewhere and needs to be repaired.
In the second case, the adapter may have been replaced due to a failure but the replacement is more limited. I kind of doubt this one as I think it would be rather unlikely to happen.
In both cases, make sure you have a backup... especially before trying to repair anything.
Last edited by jpollard; 07-22-2014 at 09:17 PM.