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Terrible transfer performance from the POOL to the Array

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Hi,

 

So I'm coming from the Truenas SCALE world to Unraid, given the installation process is broken with their latest build and my previous NAS suffered a failure requiring me to rebuild a NAS, I figured I would give Unraid a try for a second time.

 

The two issues I faced with Unraid are : 

 

1) Parity check upon system configuration took almost 1 day to complete. Is that normal?

2) I configured my system to have an array of ten 6 TB NAS drives with 2 parity and a ZFS pool of 3 TB.. The issue I'm facing at the moment is that, it takes forever to transfer 2.7 TB from the POOL to the ARRAY, in fact, since this morning (been 4 hours now), it managed to move only 600 GIGs worth of data which I find insanely slow.

 

My system is configured as is :

C2ABC2A3-7A53-4DA8-A8EA-1288545CC563.thumb.png.9878209ef63327f009b6e941744869d1.png

 

The 6 TB drives are WD 6TB SMR drives.

 

Maybe my expectations are too high given I was used to very fast read / write speeds with TrueNAS but also, is it possible that there is something wrong with my configuration somewhere? Is this normal and to be expected? I hope it isn't because I can't imagine doing backups from 1 unraid server to another with 40 TB of data, it will take many days to complete....

Edited by tessierp

  • Community Expert
1 minute ago, tessierp said:

The 6 TB drives are WD 6TB SMR drives.


This is probably your problem as SMR drives slow down dramatically when writing large amounts of data after the initial burst at the start.

  • Author

I see.. this is strange though, not something that seems to affect performance on a TrueNAS system. But that being said, they may be slower for being SMRs but to take that long to copy things like large video files? Could be that the nature of ZFS is what accelerates everything. I wonder if my solution would be to go with a ZFS array then....

Edited by tessierp

46 minutes ago, tessierp said:

1) Parity check upon system configuration took almost 1 day to complete. Is that normal?

Parity check should complete within 14hrs for 6TB, If no other disk activity. It indicate something limiting higest performance. What controller use to connect those disk. Pls provide diagnostics.

Edited by Vr2Io

I notice disk 2-9 usage are same, this look like you setting most-free allocation method, if transfer small size file, then it will further affect the performance because concurrent file will be writing to PARITY array.

 

I will check the diagnostics when I home, won't check with mobile.

Edited by Vr2Io

  • Author

@Vr2IoThank you so much for your help.

 

Unfortunately or I guess fortunately for me, I managed to find away around the TrueNAS USB thumb drive boot issue. UNRAID is definitely a great OS with many great options but I think for me to use it with the current hardware that I have, mainly those SMR drives, that will be a huge limitation factor which, TRUENAS is able to work around given how it works with ZFS. There is also the factor that I am so used to TrueNAS that I would have to learn a bunch of new things when, all I really need is to get up and running fast as I am out of a NAS at the moment.

 

Again I really appreciate your help and just didn't want you to waste time on this since. Hopefully my luck holds up a bit longer with TrueNAS until I can upgrade my hardware to something more UNRAID friendly.

Since you are not used to unraid: When writing to the array the parity calculation gives a big penalty on speed. This is why you use a cache drive to have speedy transfer and let the mover take care of moving data to the array at its leasure without you noticing..

  • Author

@Helmonder Yes I understood that, just wasn't expecting that much of a penalty on performance.

4 hours ago, tessierp said:

@Vr2IoThank you so much for your help.

 

Unfortunately or I guess fortunately for me, I managed to find away around the TrueNAS USB thumb drive boot issue. UNRAID is definitely a great OS with many great options but I think for me to use it with the current hardware that I have, mainly those SMR drives, that will be a huge limitation factor which, TRUENAS is able to work around given how it works with ZFS. There is also the factor that I am so used to TrueNAS that I would have to learn a bunch of new things when, all I really need is to get up and running fast as I am out of a NAS at the moment.

 

Again I really appreciate your help and just didn't want you to waste time on this since. Hopefully my luck holds up a bit longer with TrueNAS until I can upgrade my hardware to something more UNRAID friendly.

Welcome and note.

  • Community Expert
13 hours ago, tessierp said:

TRUENAS is able to work around given how it works with ZFS.

You can also create a zfs pool with Unraid, but note that those SMR drives are not recommend for zfs pools, same with TrueNAS, they can timeout during a resilver:

 

https://www.truenas.com/docs/hardware/notices/wdsmr/

On 11/4/2024 at 12:40 AM, Vr2Io said:

Welcome and note.

Unraid also does zfs

Turbo write would also speed thing up somewhat though it's no magic bullet.

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