SOLVED Server to Mac SMB speed starts fast and slows to crawl.

[Robertr]

Browsing SMB shares from the Mac is fast.
Any copying/downloading from the server starts really fast (over 100MB/s) but this only lasts for a few seconds before it slows to a crawl with intermittent bursts of 30-60MB/s.
Copying/uploading to the server also fluctuate a bit in speed but usually over 100MB/s.
iperf3 3 speeds are consistently 112MB/s in both directions.
I'm running macOS Catalina 10.5.5 (SMB3 I think).

I have searched for solutions but haven't found any.
If anyone can help me find a fix for this I will be very grateful.

My HW is in the sig.

 

[Yorick]

Large files or bunch of small files? What do your ARC statistics say?

If this is loads and loads of small files I am wondering whether tuning ARC to hold more metadata might help.

 

[Robertr]

It's large files like movies and such.
I don't think it's about the ARC, when I was running 10Gb on the same server I managed to almost max out the network speed but that was with another Mac and a different FreeNAS install.
Arc :
min: 73.51 mean: 96.17 max: 99.92

 

[Samuel Tai]

This other thread may have some ideas to try.

SMB Performance on MacOS

In an effort to more concisely capture the problem at hand, I'm beginning a new thread instead of continuing on this one. I'm also posting in general as I'm not sure if this is storage, networking or some other unknown problem. Problem: Perceived slow transfers over SMB sharing to Mac...

www.ixsystems.com

 

[Robertr]

Thanks a lot for the help.
I'm quite embarrassed to let you know that the problem is "solved" in a most unexpected way...
When I copy from the server to a RAM disk I get full speed.
It seems it's actually the MacBook (2012) or the SSD in it that is giving the problem. So stupid I can hardly believe it.
I'll have to look further into it.