During performance troubleshooting, you notice that the disk device sdc on Storage Node 3 is...

The increased I/O on sdc is expected when that device corresponds to storage volume 0 (/var/local/rangedb/0), because StorageGRID uses volume 0 for the Cassandra database that stores object metadata. NetApp documents that StorageGRID maintains object metadata independently from object data in Cassandra and reserves space specifically on volume 0 of every Storage Node for metadata storage and essential database operations.

Cassandra performs continuous metadata-related activity, including database reads and writes, compaction, indexing, consistency operations, and repair. Consequently, the disk containing volume 0 can exhibit noticeably higher I/O than the remaining object-storage volumes even when object data itself is reasonably balanced. NetApp diagnostic examples also show sdc associated with /var/local/rangedb/0, illustrating the relationship between this device and the StorageGRID metadata volume.

Option A does not explain persistent device-specific activity because object ingest is handled through StorageGRID services and ILM placement. Option B would indicate an object-placement issue rather than systematically higher I/O on volume 0. Option D is also incorrect because higher utilization is not necessarily caused by a larger number of stored object payloads.

Reference topics: Storage Nodes → Storage Volumes → Volume 0 → Cassandra Object Metadata → Disk I/O and Performance Monitoring