Unraid SMB Performance: v6.7.2 vs. v6.8.1

I previously wrote about the poor SMB performance I experienced in Unraid v6.7.2. Unraid v6.8 supposedly addressed SMB performance issues for concurrent read and write operations, and after waiting for the first bugfix release of v6.8, I re-tested using v6.8.1.

In my last test I used a combination of batch files and copy and paste, this time I wrote a tool to make repeat testing easy. I am not going to describe the usage here, see the instructions at the GitHub repository. There are new reports in v6.8 of poor SMB performance when a folders contains large numbers of files, so I added a test to try and simulate that behavior, by creating a large number of files, then reading each file, then deleting each file.

I configured my Unraid server with two test SMB shares, one pointing to the cache, and one pointing to a single spinning disk. The cache consists of 4 x 1TB Samsung Pro 860 drives in a BTRFS volume, and the spinning disk is a Seagate IronWolf 12TB disk formatted XFS protected by a single similar model parity disk. The third share is backed by a Windows Server 2019 VM running on the cache disk.

I upgraded the server from v6.7.2 to v6.8.1, verified operation, and then restored it back to v6.7.2. I ran the first set of tests with v6.7.2, upgraded to v6.8.1, and re-ran the same set of tests. Both tests used exactly the same hardware configuration and environment, and were run back to back.

Here are results in graph form:

Sum of MBPS
Sum of MBPS and BlockSize
MBPS at 1MB BlockSize
MBPS at 1MB BlockSize no W2K19
Iteration Time

What did we learn?

  • Windows Server 2019 SMB performance is still far superior compared to Unraid.
    • I don’t know if the Linux SMB implementation is just that much slower compared to Windows, or if the performance degradation is attributed to Unraid.
    • TODO: Test SMB performance between a Linux VM and Windows VM.
  • The cache performance in v6.8.1 is worse compared to v6.7.2.
  • No noticeable SMB performance improvement in v6.8.1.


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