Synology slow writes fast reads

I can not pinpoint what is causing this but my sumology has extremely slow wrote speeds. I.e 2MB/s vs read of 500MB/s. This has only been an issue since switching from linux to windows. I have mtu aet to jumbo frames as ibhave all my devices running 5gbit or faster.

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Not sure what freedom /access you have on the synology, but If I had that on a nas/server/machine, I’d start top down locally

Starting on the synology, try a local memory write/ write to ramdisk
Then save / copy a file locally between datasets / drives, see if is a drive / array issue

Set MTU down lower for testing, for now. then check like iperf or some transfer to synology ramdisk, see if it’s a network issue?

Then maybe check network saving?

not even sure if you can access the synology to test local jobs.

MTU low like 1200 should stop bottlenecks/amplifications/etc.
Jumbo frames are good for network throughput, but 2MB/s means there is a problem somewhere

[edit: linked a Reddit post where someone installed a package that includes iperf, and a command line tool to test it. looks pretty cool (same link again)]

Docker is how I ran iperf3 on my Synology also. For reference I was able to get >95% of the 10g link speed even though I was using a VM on one end and docker on the other.

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Which model do you have? I bought mine in 2019 before 10gbase t was offered.

I got the Ryzen based one Wendell did the review on recently. Pretty nifty machine.

I have one of their lower end, gigabit, rack mount units also as a backup target. Gigabit links are slow when you’re moving hundreds of gigabytes around, but that’s all automated, so it’s not like I’m sitting around waiting for it.

It seems to be a network issue with either the nas or somewhere in between. Because direct file transfer from one pool to another is fast. I am using a 5GBASET USB Dongle and also have a bonded 1gbit as fault tolerance.

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I’d look at the USB adapter first.

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And wag your finger at it…

Let’s take a moment to thank the creators of USB and GPU drivers for providing us with endless hours of… stuff to occupy us.



Knock on wood the usb dongle seems to be an issue. I have 4 x 5gbaset dongles and the new one was hitting 180MBPS. Normally I see 400 but that is a step in the right direction. I also switched to a different usb port. 300MBps read and 200 ish write.

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Was it you or regular that deleted their library last night?


Regular had that problem

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amen to my hoarding. and accidental purchases. I bought like 2 refurbished dongles and 3 new. THe refurbished were 50bucks and a week laters they went on sale for 60 new. so bought another 3 for various devices that i cant upgrade the nice to.

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I have 10G cards, but just use 1G.

good enough for me and my network

I do heavy bluray transfers helps to have 10 and 5G.

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I just saw 300MB on write with the new nic.


10g cards can get pretty toasty, and some still don’t “just work” depending on your setup. Easier to stay with gigabit if you don’t need it.

I have a 10g link between workstation and NAS, but everything else is still gigabit. The nuc has a 2.5 gigabit nic, but I don’t use it because I didn’t want to mess with running a cable to it.

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Yea 7 of my 8 homelab systems are 10 G my macbook and synology and mini pc are 5G

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do you need a 5G switch to communicate with them at 5g?

Or are the 10G NIC’s new enough to do 10+5+2.5+1?

my 10G dual NIC add in cards, only do 10G or 1G, depending on SFP modules

I don;t have anything that can do 2.5 or 5g

IIRC, older 10G NIC’s wouldn;t do 5 or 2.5G speeds?

Unless I’m wrong… would be nice to be corrected, and that my old chelsio cards would “just work” if I connect a 5g or 2.5g sfp+ into it…

Yeah that happens. Some can step down to multigig speeds, but some older hardware can’t. Without a review from STH or something it’s hard to know what you’re going to get.

I have these, and they can step down, but I’m not sure about USB adapters. Never used one of those at multigig speeds.

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