I am looking for advice on how to identify performance issues with a ZFS storage server. The server is a prototype that I have built as a proof of concept for a NAS device that will allow me to offload camera memory cards to shared storage. We are talking around 512GB transfers with checksum verification processed by the client. I have a fair bit of Linux experience, but opted for FreeBSD for this build as its native support for ZFS.


  • FreeBSD 12.1
  • Intel Xeon E3 1225
  • Intel S1200BTS Motherboard
  • 16GB DDR3 Ram
  • Dell H310 flashed to IT mode (installed in a 16x slot)
  • Aquantia aqc107 10gbe network card.
  • 6x 2TB HGST Ultrastar SAS drives. (Configured into one RAID 0 storage pool)

  • Network Protocol Samba

Initial Expectations

I was hoping that the server would run at around 900mbps read and write over 10gbe.

Testing and Results

I have found it difficult to measure pool speed over 10gbe as the tools that I usually use have not been able to give me a consistent result. I have tested with AJA speed test and Blackmagic Disk Speed Test and get different results from each. AJA: 140mbs Write / 80mbs Read Blackmagic: 450mbs Write / 80mbs Read

Actual use offloading camera memory cards to server using Hedge offloading software 10GB transfer averages around 170mb per second.

I these results were strange and quite low for my expectations. I have tested the transfer speeds with a Ramdisk and got around 1GB per second each way, which rules out the actual connection.


  1. Why does the benchmarking software report different speeds?
  2. What is the best way of identifying the bottleneck in this situation? My initial thoughts that it maybe the Dell H310
  3. Will configuration and caching help in this case? Or is the issue purely hardware related.

I think I have included everything that will be useful to solve this issue. Please forgive me if anything has been omitted. H

  • This may require more than the format here allows… Try me off-line, as I think I can help with your application.
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    Dec 13, 2019 at 18:13
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    Dec 13, 2019 at 18:34

1 Answer 1


In general, that not enough RAM or the correct disk setup to accommodate those transfer speeds.

Beyond that, there the matter of tuning:

  • Network tuning
  • SMB protocol tuning
  • Linux system tuning
  • ZFS filesystem tuning
  • Disk and ZFS pool layout
  • Caching
  • Hardware design

What you’re asking for is definitely possible, though.

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