Filesystem remounted read-only
Kernel forced a filesystem to read-only mode, usually due to I/O errors. Services that write to this mount will fail. Data already on the filesystem is readable; new writes are not.
Remediation
When this rule fires on one of your servers, the dashboard alert detail page renders the full remediation guidance: the command to run, what to verify after, and Furnace's annotation for your specific distro + hardware. Sign in at app.glassmkr.com to see the live alert.