I clicked Save and got the error:
common.exception.SfdcSqlException: ORA-20003: ORA-06512: at
"GRUMPY.CSTORAGELIMIT", line 252 ORA-06512: at "GRUMPY.CSTORAGELIMIT", line
734 ORA-06512: at "GRUMPY.CSTORAGELIMIT", line 785 ORA-06512: at
"GRUMPY.CSAVEUTILS", line 429 ORA-06512: at
"GRUMPY.CSTANDARDENTITYDATATEMPLATE", line 2085 ORA-06512: at line 1 {call
cStandardEntityDataTemplate.insert_stdentdatas(?,?,?,?,?,?,?,?,?,?,?,?,?,?,
?,?,?,?,?,?,?)} {call
cStandardEntityDataTemplate.insert_stdentdatas(?,?,?,?,?,?,?,?,?,?,?,?,?,?,
?,?,?,?,?,?,?)}
But in System Overview I see that I have only used 13% of 200MB (it's a developer sandbox).
It was not a one-off: again clicking Save (a change on a Case record) gave the same message. And clicking again and again doesn't help. I also get the same error when trying to change a different Case record. Clearly some storage limit is exceeded, but I don't know which.
According to Salesforce's trust site, there's nothing wrong with the instance - CS86.