[SOLVED] Long Pauses with File Transfer

[lytener]

[TL;DR]

I had issues with transfer speed from a Mac (40 MB/s). I fixed it with reducing the Delayed TCP ack to 0 and now get about 110 MB/s.

 

[SOLVED]

I went through a bunch of search results and ended up finding this:

http://www.debugginlife.com/solved-very-slow-file-transfer-on-mac-shares-smbafp/

 

 

In summary, try running this command in your terminal:

sudo sysctl -w net.inet.tcp.delayed_ack=0

Remount the share and test your speed. I used Blackmagic Disk Speed and iperf3 to test it out. This is a temporary fix. If it works for you, then you'll have to edit your /etc/sysctl.conf file and add

net.inet.tcp.delayed_ack=0

 

Other fixes people have tried are: 

1. Disabling SMB signing
2. Changing from SMB to AFP

 

 

[ORIGINAL POST]

I'm new to Unraid and managed to get most of my server setup and would appreciate any advice. I'm migrating a lot of files (movies, tv shows, photos, etc...) over and I'm experiencing a very strange issue where there are long pauses in my transfer. I'm transferring about 7.5 TB and it's been about 2 days. My two issues are:

 

• SMB network transfers will suddenly pause for a period of time. It doesn't appear that the cache is moving anything to the array at this time.
• Identifying bottlenecks. My network transfers are hitting about 40 MB/s when it's actually working (Mac Mini with direct attached storage @ 220 MB/s --> Unifi network configured for jumbo frames --> UnRaid server with 1TB SSD Cache --> Disk Array with WD 10TB Red Drives capable of 210 MB/s sequential writes). 

 

The Unraid server has a 1TB cache drive and is set to automatically move data at 70% utilization. The long pauses don't occur when the SSD is moving data. The Unraid server is capable of hitting 900 Mbps (112 MB/s) on external speed tests. The network transfers will get to about 40 MB/s and then suddenly stop for long periods of time. I don't see much I/O activity on the Main section of my Unraid server. I would appreciate any help.

 

I've attached the diagnostic file if anyone with experience can take a look. 

 

 

Edited July 24, 2020 by lytener
Solved!

[JorgeB]

Initial transfer should be done without using cache, you can enable turbo write for increased performance, but 40MB/s should be possible even without it.