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fka

Slow write speeds to array

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Hi all

 

I've recently installed a trial of unraid 6.7.0, now updated to 6.7.1 to my HP Microserver Gen8. Currently I only have two drives in the array, a 4TB WB Red and a 2TB Seagate Barracuda, no parity drive and no cache drive. The plan is to migrate from WHS 2011 running on my HP N36L to unraid on the Gen8. Once migrated I'll add a second 4TB WD Red to be set as a parity disk, 1 more 2TB Barracudas and a 250GB SSD as a cache disk.

I've avidly followed Spaceinvader one's excellent guides, preclearing my HDDs, built the array, created shares and am currently at the stage of moving media from my WHS machine to the unraid machine using Krusader.

 

Considering I have no parity disk, whist moving my movies collection (mostly 10 to 70GB mkv files) I'm seeing transfer speeds top out at around 40MB/s.

I've benchmarked the drives using the DiskSpeed docker, the WD tops out at around 140MB/s dropping off to 65MB/s at 4000GB, and the Seagate around 170MB/s trailing off to 70MB/s.

I've tested my network speeds using a speedtest docker with reverse proxy on a client connected to the same switch as the unraid machine. I'm easily topping out my 1Gb connection.

To a different client again on the same switch, I can copy from the SMB share on my WHS to an SSD topping out 1Gb and to an HDD at around 80 to 90 MB/s.

The FCP plugin shows no issues and I've checked write caching is enabled on both drives in the array. I've also tried setting reconstruct write and this made no difference, which I assume it shouldn't since I currently have no parity drive... All array disks are SATA .. 

 

Am I being unrealistic to expect a write speed higher than 40MB/s? Or any other suggestions/ tips would be very much appreciated.

 

Many thanks

D

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Posted (edited)

Yes, Turbo write on or off wouldn't affect in your case.

 

Pls check does traffic route thr router or proxy, and check they are in same subnet / netmask.

Edited by Benson

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Posted (edited)

Hi Benson and thanks for your reply.

Yes all these devices are on the same subnet and in the case of the WHS and UNRaid server both are on the same switch. A traceroute from either machine to the other is a single hop.

 

Cheers

D

Edited by fka

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Incidentally I can copy from a USB3 flash drive mounted on the UNraid machine to the array at around 180MB/s, currently filling the faster seagate drive. So I assume the slow transfer speed I'm seeing from the WHS smb must in some way be a network issue...

 

Reading from the array to another machine on the same switch is maxing out 1Gb. But writing from either my WHS smb or an smb I have on an OS X server tops out at aprox 40MB/s..

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Then not much idea, but if you got a very flat ceiling curve, then it should network issue rather then disk issue I guess.

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When you transfer 1 single very large file (pick you 70GB mkv for example), what speed do you get? Does it flat line or fluctuate?

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Thanks Benson, I'll keep messing around with it. I still haven't swapped out any of the cables and I can try a different switch but I've not had any other issues so may be clutch at straws ..

 

Hi testdasi - I'd say flatline at around 38MB/s occasionally climbing to around 40MB/s or dropping to 36MB/s. I wouldn;t say they are fluctuating just slowly drifting around 38MB/s..

 

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7 minutes ago, fka said:

Hi testdasi - I'd say flatline at around 38MB/s occasionally climbing to around 40MB/s or dropping to 36MB/s. I wouldn;t say they are fluctuating just slowly drifting around 38MB/s..

That sounds like network problem. Install the Tips and Tweaks plugin and try disabling NIC Flow Control and/or NIC Offload to see if it helps.

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Disabling flow control made no noticeable difference. Disabling offload actually slowed the transfer down slightly, repeated several times but averaged aprox 36MB/s.

 

Thanks

D

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totally crazy idea incoming: 

I was experiencing 20/mbs when SMB transferring into the array from a windows machine but when i am within a VM and do the same transfer i can now get 60-90/mbs have no explanation but it definitely helped, so if you have the free time fire up a win 10 vm and try initiating the transfer and see if the speeds increase

<end crazy: Idea>

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I think I've sorted this.. I'd not added my WHS smb shares as a "remote smb". I'd simply added the WHS smb in Krusader using "New net connection"

Having added the remote smb using "Add Remote SMB/NFS Share" and mounting it, I'm seeing 100MB/s + transfer speeds.

 

Thanks to all for your support and apologies for my noobishnes :)

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