{
  "id": 19284689,
  "title": "Benchmarking 10GbE NAS-to-NAS Transfers: iperf, NFS, cp, and rsync",
  "url": "https://urgent.news/2026/11/10/benchmarking-10gbe-nas-to-nas-transfers-iperf-nfs-cp-and-rsync",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-11-10T04:51:25.000Z",
  "source": {
    "name": "Dev.to",
    "slug": "dev-to",
    "url": "https://dev.to/nha6ki/benchmarking-10gbe-nas-to-nas-transfers-iperf-nfs-cp-and-rsync-4p1j"
  },
  "original_language": "en",
  "account": "On November 9–10, 2026, a series of performance tests were conducted on two Synology NAS systems connected via a 10Gbps network. The objective was to benchmark different file-copying tools and understand their impact on file-transfer speeds.\n\nThe tests involved copying a 15.17 GB file (16,285,199,445 bytes) between the two NAS systems using several methods: iperf for network throughput, dd for raw data copying with and without fsync, cp for the built-in Synology copy command, and rsync for a remote file-copying utility.\n\niperf measurements showed that the network could sustain around 9.42 Gbps of throughput. However, actual file-copying speeds were significantly lower when using cp (494 MB/s) or rsync (181 MB/s). The discrepancy between network bandwidth and file-copying performance was attributed to additional processing overhead introduced by the file-copying tools, such as checksum computation, data fragmentation, and filesystem-specific operations.\n\nA parallel copy test using two rsync processes demonstrated that splitting the data across multiple output files resulted in a 55% increase in aggregate throughput (281 MB/s), compared to a single rsync process. However, this method also increased CPU usage and resulted in longer individual copy times.\n\nThe CPU and RAID activity measurements revealed that cp generated the most RAID write traffic and consumed more CPU time in kernel mode, while rsync utilized more user-level processing time. These factors likely contributed to the slower single-process rsync performance.\n\nIn conclusion, the test results indicated that the choice of file-copying tool significantly impacts the overall performance, even when the network infrastructure is capable of high-speed data transfer. While iperf demonstrated the network's theoretical throughput, actual file-copying speeds were limited by the overhead introduced by the chosen utility. The findings underscore the importance of selecting appropriate tools and understanding their underlying mechanisms when planning data migrations or large-scale file transfers.",
  "summary": "One of our Synology NAS systems was nearly full, so I planned to move data to another NAS over our existing 10GbE network. Before migrating anything, I wanted to establish realistic file-copy performance without modifying the NAS configuration. iperf2 reached 9.42 Gbps , but the copy commands told a different story: cp completed a large-file copy at 479–494 MB/s , while a single rsync process…",
  "key_points": [
    "Benchmark tests conducted on November 9-10, 2026, using Synology NAS systems",
    "iperf showed 9.42 Gbps network throughput, but file-copying speeds were lower",
    "cp and rsync had significantly lower transfer speeds (494 MB/s and 181 MB/s)"
  ],
  "editors_take": "The gap between network capacity and actual transfer speeds shows that software overhead and processing methods often dictate performance more than the underlying hardware infrastructure during large-scale data migrations.",
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}