During performance troubleshooting, you notice that the disk device sdc on Storage Node 3 is handling significantly more I/O operations than the other disks.
What is the reason for this behavior?
A.
The client is ingesting directly to this node.
B.
There is poor distribution of erasure coded data chunks.
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
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