My Drobo FS is reporting that it is critically low on capacity, but it’s not. Or it shouldn’t be.
It is populated with 5 healthy drives of 3TB each, it’s configured for dual disk redundancy and should thus have more than 8TB of usable space and the data I’ve put on the Drobo is only 3.9 TB.
- The Drobo FS has been quite stable for some time, though I’ve had to replace drives over the years. Mostly WD NAS RED drives now. When this started it had four 3TB drives and one 2TB drive.
- Oct 20: unplanned power outage, after which Drobo Dashboard reported “mount failed.” I proceeded with a repair operation (initiated through Drobo Dashboard) which took only about one day, after which I rebooted (again through Drobo Dashboard) and it was then able to mount everything but it showed a red light on the 2TB drive saying the system is critically low on space and the drive must be replaced with a larger one.
- I first replaced the 2TB drive with another 2TB drive I had on hand and after the data protection operation completed, it complained of the same problem (critically low on space)
- I replaced the 2TB drive with a 3TB drive, and after about 1.25 days of rebuilding it again says critically low on space and I should replace the top drive (3TB).
I don’t know how to interpret all of the diagnostic space readings:
TotalCapProtected: 8908807864320 UsedCapProtected: 3875358380032 FreeCapProtected: 0 TotalCapUnprotected: 0 UsedCapOS: 8908807864320 Unallocated: 0 UseUnprotectedCap: 0 AvailableForData: 8908807864320 AvailableForData_SDR: 11981860061976 AvailableForData_DDR: 8908807864320 UsedForProtection: 6078773146194 ReservedForExpansion: 0 Overhead: 15383899566 TotalPhysicalCapacity: 15002964910080 UnallocatedCapacity: 0 TotalCapacityPT: 0 CapacityCache: 0
But TotalCapProtected, UsedCapProtected, and TotalPhysicalCapacity looks correct.
The device seems otherwise happy, and I can mount the shares but have avoided doing so in case I might cause some corruption.
Has anybody seen this behavior, can you recommend what I should do next to resolve it?