Slow Transfers from Unassigned Devices to Array

[SloppyJoe]

Hello. 

 

I recently set up my UnRaid server.  It consists of 4 12TB drives with one of them being parity so I get 36TB of storage.  I've been trying to transfer my existing data over to the array but have been getting slower speeds than I was expecting.  

 

Initially I transferred over the network but was getting large transfer swings between 20-80MB/s throughout the transfer if I transfer directly to the array (transferring to cache is fine)... but the network issue is another story.  

 

So next I connected the drives directly to my server (internal sata ports on the motherboard) and mounted them using unassigned devices.  I've tried transferring data into my array (user0 so it goes straight to array) using Krusader but an average of 80-90MB/s transfer rates... and with less of the large swings.

 

Finally I read on one of the threads to use the terminal console and just use the cp command and to pause/turn off all my containers/vm.  But it gives me pretty much the same transfer speeds as using Krusader.... around 80-90MB/s.

 

I do have turbo write (reconstruct write) turned on, am writing directly to the array, and all this was started after the parity drive was built.  

 

Am I forgetting something?  Or is this normal for writing directly to the array.  

 

It's been less than a week since I started using Unraid so I'm still learning all the different features/settings.  Apologies if this has been answered somewhere already.  

 

 

 

Edited October 25, 2020 by SloppyJoe

[trurl]

6 minutes ago, SloppyJoe said:

is this normal for writing directly to the array.

yes

 

I know you said you are using turbo but did you read about that? Here is a wiki link that explains how parity updates are done with each mode so you can see why parity updates affects writing speed.

https://wiki.unraid.net/UnRAID_6/Storage_Management#Array_Write_Modes

 

[SloppyJoe]

Thank you for your response..  Yes I did read about that and I do understand why it will be slower.  I think I was concerned something might be misconfigured because I saw other threads where users are getting around 200MB/sec transfer rates and I'm not even hitting 1/2 of that.  

 

I guess I just didn't expect array writes to be slower than gigabit speeds.  I was planning on upgrading my network to 10gbit in the future... but if this is normal write speeds, it's going to be hard to justify that cost.  

[trurl]

4 minutes ago, SloppyJoe said:

users are getting around 200MB/sec

Almost certainly to cache, though I know a few have all SSD arrays

[SloppyJoe]

 

This was the thread I was looking at.  He does transfer from SSD but to mechanical arrays.  

 

 

Here's a screenshot the speeds of my array.. mid transfer.  

 

 

[JorgeB]

You appear to be using the "most free" allocation method, that's very bad for performance due to overlapping writes to parity.