[SOLVED] Really slow (50 MB/s) transfer speed between disks on UnRaid - Even with parity turned off

[jbssm]

I installed unRaid yesterday, and despite its very nice features, it is extremely slow when compared both with Proxmox and TrueNAS on the exact same system.

 

I am copying my files from another drive, mounted on unRaid, where I have the backup from my old install, to my unRaid array with rsync, and I am getting speeds of 50 MB/s

 

• Results with XFS and BTRFS are mostly the same (I reformatted my array to see if that was the problem).
• Parity drive is deactivated
• Speeds both on Proxmox and TrueNAS (only with 2 cores active) for the same system, where between 150 to 180 MB/s
• As you can see, DiskTest results done on UnRAID show a top speed between 200 MB/s to 100 MB/s
  
  So, what is going on here? Disks seem to read just fine, so why it's so slow to copy data between disks on UnRaid when it's not with other OSs?

 

Edited June 17, 2021 by jbssm
mark as solved

[JorgeB]

Please post diagnostics grabbed during a slow transfer, also post the rsync command used.

[jbssm]

Hi and thank you.

 

What diagnostics are you talking about?

The rsync command is: `rsync -ah --info=progress2 originFolder /mnt/user/media`

The media folder in question is a share without any cache drive assigned.

Edited June 16, 2021 by jbssm
add info

[JorgeB]

1 minute ago, jbssm said:

What diagnostics are you talking about?

Tools -> Diagnostics

[jbssm]

Thank you. Here they are:

 

 

homer-diagnostics-20210616-2314.zip

[JorgeB]

Parity is assigned but invalid, you need to let the parity sync finish or completely unassign it.

[jbssm]

Thank you, this seems to have been the issue: pausing the parity is not enough, I needed to unassign it. Now the read/write speed is proper once more.

[JorgeB]

Note that with just one data drive having parity (once it's synced) won't degrade performance, since it works like raid1, with more than one data drive you can enable turbo write, without controller bottlenecks it will write as fast as the slowest array disk can read/write, at the expense of all disks spinning up for writes.

[Cyaankali]

Hi JorgeB,

I have the same problem as jbssm.  The parity check is disabled and i am using 8 4TB disks.  Two disks of them are parity so i don't lose any data. The maximum transfer speed is still 50mb/s.  

 

 

bobken-diagnostics-20230305-1515.zip

[Kilrah]

As mentioned pausing a parity check/sync only suspends checking/calculating the rest of the disk, parity is still updated realtime for any writes that are being done.

You cannot suspend parity without unassigning all parity drives and rebuilding them entirely later (and having no protection for that duration).

 

You also don't have Reconstruct writes enabled.

Edited March 5, 2023 by Kilrah

[Cyaankali]

14 minutes ago, Kilrah said:

As mentioned pausing a parity check/sync only suspends checking/calculating the rest of the disk, parity is still updated realtime for any writes that are being done.

You cannot suspend parity without unassigning all parity drives and rebuilding them entirely later (and having no protection for that duration).

 

You also don't have Reconstruct writes enabled.

Thanks for your reply so if i understand this correctly i'll have to run the parity check again and i changed Tunable (md_write_method) into reconstruct writes.

[JorgeB]

18 hours ago, Cyaankali said:

Thanks for your reply so if i understand this correctly i'll have to run the parity check again and i changed Tunable (md_write_method) into reconstruct writes.

Yes, finish the parity sync first then you can use turbo write.

[Cyaankali]

On 3/6/2023 at 10:16 AM, JorgeB said:

Yes, finish the parity sync first then you can use turbo write.

 

Hi JorgeB, 

I really don't know what the problem is with the transfer speed between my desktop pc and my NAS device but i runned the parity check again and changed Tunable (md_write_method) into reconstruct writes afterwards but it's still maximum 50mb/s.  Why is this so slow?

I don't have the option to use a cache disk so i am just running 8 Seagate Barracuda 4TB disks and two of them are parity.

Edited March 7, 2023 by Cyaankali

[JorgeB]

34 minutes ago, Cyaankali said:

i am just running 8 Seagate Barracuda 4TB disks

Are these SMR disks? Post the diags during a transfer.

[Cyaankali]

1 hour ago, JorgeB said:

Are these SMR disks? Post the diags during a transfer.

 

I checked a list of Seagate disks and it says that ST4000DM000 are CMR disks.

[JorgeB]

14 hours ago, JorgeB said:

Post the diags during a transfer.

 

[Cyaankali]

On 3/8/2023 at 9:23 AM, JorgeB said:

 

See attachment for more information.

[Kilrah]

No diags attached.

[Cyaankali]

7 hours ago, Kilrah said:

No diags attached.

How can i attach diags during a transfer?

Edited March 10, 2023 by Cyaankali

[Kilrah]

You start a transfer and while that's running go grab the diagnostics?

[Cyaankali]

11 hours ago, Kilrah said:

You start a transfer and while that's running go grab the diagnostics?

 

 

bobken-diagnostics-20230310-1955.zip

[JorgeB]

Disks are writing faster than that, suggesting you have a LAN issue, run a single stream iperf test in both directions.

[Cyaankali]

2 hours ago, JorgeB said:

Disks are writing faster than that, suggesting you have a LAN issue, run a single stream iperf test in both directions.

After a lot of trial and error i received the following:

[  4]   0.00-1.00   sec   112 MBytes   943 Mbits/sec
[  4]   1.00-2.00   sec   113 MBytes   947 Mbits/sec
[  4]   2.00-3.00   sec   113 MBytes   946 Mbits/sec
[  4]   3.00-4.00   sec   113 MBytes   949 Mbits/sec
[  4]   4.00-5.00   sec   112 MBytes   943 Mbits/sec
[  4]   5.00-6.00   sec   113 MBytes   947 Mbits/sec
[  4]   6.00-7.00   sec   113 MBytes   944 Mbits/sec
[  4]   7.00-8.00   sec   112 MBytes   944 Mbits/sec
[  4]   8.00-9.00   sec   113 MBytes   947 Mbits/sec
[  4]   9.00-10.00  sec   113 MBytes   949 Mbits/sec

So i installed iperf3 on my server and i used the iperf3 tool on W10 after using iperf3.exe -c and the ip address.

Edited March 10, 2023 by Cyaankali

[JorgeB]

That looks good, is that from the pc to the server? I had asked for both directions. 

[Cyaankali]

1 hour ago, JorgeB said:

That looks good, is that from the pc to the server? I had asked for both directions. 

 

This is from the pc to the server but i don't know how i can manage this from the server to the pc?  If you can help me on the way that would be grateful.