Slow internal transfer speeds NVME -> SATA

[Mihael]

Hi guys, 

 

This topic has been posted a couple of times, but a correct solution was not found.

 

 

I use 8 drives, 7 of them are ironwolf and one Toshiba x300, they are all fast disks. additionally I have 2 NVME SSD as cache in the Raid1.

 

I mainly use Unraid for Plex. I use the usual apps like radar, sonar, sabnzb etc.

 

 

I had Sabnzb set up so that he writes directly to the HDDs without cache, that I do not unnecessarily write on the SSD cache. Although I have a 1 gbit fiber line I noticed the sab never downloads over 20 mb/s.

 

 

I thought I would create a new share which is CACHE only and sabnzb should download and unzip the data there.

 

 

and what happens, the data is downloaded faster and unpacked way faster. Great!

 

But if I now copy the data from the cache to the discs with Krusader, I get a maximum transfer rate of 20-40 mb/s.

MiB/s

 

 

Did someone have the same problem?

 

 

Can it be due to the different formats? The cache drives are btrfs and the disks in xfs.

 

But the direct download to the disks is slow.

 

This is very sad if even the download directly on the disks (hdds) is slow.

 

 

Thank you for your help!

Edited November 21, 2019 by Mihael

[trurl]

Sounds like it could just be the normal write speed of parity. 

 

Have you tried Turbo Write? 

https://forums.unraid.net/topic/50397-turbo-write/

 

[Mihael]

5 minutes ago, trurl said:

Sounds like it could just be the normal write speed of parity. 

 

Have you tried Turbo Write? 

https://forums.unraid.net/topic/50397-turbo-write/

 

Yes, I did. It's installed. Do I have to change the settings?

 

 

That's pretty slow, especially if all drives are fast. Would it help if I would connect the HDDs to a PCI-E controller instead of motherboard? All 8 discs are connected to the Asus motherboard now.

 

 

I noticed that the first 3-5 seconds transfer rate is 500mb/s and then drops to a constant 25-50mb / s.

 

Thank you!

 

 

[testdasi]

27 minutes ago, Mihael said:

Yes, I did. It's installed. Do I have to change the settings?

 

That's pretty slow, especially if all drives are fast. Would it help if I would connect the HDDs to a PCI-E controller instead of motherboard? All 8 discs are connected to the Asus motherboard now.

 

I noticed that the first 3-5 seconds transfer rate is 500mb/s and then drops to a constant 25-50mb / s.

 

Thank you!

 

 

 

Your current Write Mode is "Normal" i.e. Turbo Write is off.

I would suggest doing your test without the plugin. The settings for Turbo Write is controlled natively in Unraid settings

You don't actually need the plugin to turn it on and for testing purposes, having the plugin introduces a variable i.e. it can turn off Turbo Write when you want it on etc.

 

For your other questions:

• No. Won't be faster.
• The initial bust is due to write caching in RAM.