SMB File Share Extremely Slow

I have a freshly installed and updated version of Windows Server 2016, I have 4x 4TB disks, connected through SATA. These disks are setup in a parity configuration under a StoragePool, in that I have made a virtual disk of ~10TB.

Write operations to the disk go around 10MB/s after the RAM buffer has filled, an ideas why?



  • Iperf3 – Network connection is working correctly.
  • CPU Load – 10% or lower.
  • Hardware Failure – Disk drives are functional and controller works fine on individual disks.


The Storage Pool’s Write Pattern

iPerf3 Results

Write Pattern During LOCAL C: to O: Transfer (No Networking):

Requested Info:

  • Disk RPM/Size: 7200RPM (LFF)
  • Disk Models: WD40EFRX (Western Digital: Red “NAS” Drives)
  • Storage Pool Setup: See Here
  • What kind of server? Custom-Chassis PC Case with a “Asus P8Z77-V LE Plus” Motherboard.
  • How are disks connected to it? 12 Disks, 4 of which are relevant to this file share.

Additional Notes
– The system was performing in the range of 200MB/s previosuly with FreeNAS 11.4.


The default settings will not fit.

Optimizing Storage Spaces (recommended way)

Setting the interleave should be done without GUI with PowerShell: New-VirtualDisk -Interleave

I would not recommend to change the IsPowerProteced settings or enable write cache on the physical disks.

Source : Link , Question Author : ISJ , Answer Author : Andreas Rehm

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