Facts About Latency
NAS Performance Pitfalls: Inside the Box
NAS performance problems frustrate and plague storage administrators. It’s an endless time-consuming struggle to isolate and fix performance bottlenecks. Latency or delay is at the heart of the matter. Latency is measured as round-trip-time for a data packet to transit between two specific points but is experienced by users as slow application response time and manifests as muttering and explicatives.
1. Conventional hard disk drives (HDDs) high latency, low IOPS,
and poor throughput.
- HDDs are a bottleneck, delivering prohibitive read and write latencies.
- Large numbers of HDDs are required to help fill IOPS requirements.
2. Excessive NAS controller processor utilization.
- NAS cycles used for snapshots, deduplication, replication, storage tiering, thin provisioning, file system, virtualization integration, backup software integration, layer 7 NFS processing, networking, reads, writes, and NFS metadata processing can add up and lead to processor contention and increased latency.
- NFS and CIFS are chatty protocols that consume NAS controller cycles and system bandwidth.
3. Meager network throughput.
- NAS systems can’t process data IO fast enough.
- NFS Metadata is very chatty and consumes NAS controller cycles before Reads and Writes are executed.
- NFS Metadata can be as much as 90% of the total NFS operations.
- NAS controller cycles are rapidly consumed by processing data IO and data copies that amplify the latency chokepoint.
- TCP/IP inherent latency reduces IOPS and effective data throughput across the network.
These 3 root causes of NAS lackluster performance are enormously problematic to overcome inside the NAS system or “box”.