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169 posts

Master Geek
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Topic # 204656 11-Oct-2016 16:43
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Possible the dumbest question ever/noob blindness, but here I go nonetheless...I'm a little confused by the supposed speeds I'm getting with the LAN Speed Test utility when sending a 90MB test file to my NAS box. The results are, apparently:

 

 

Then, I transfer an actual 90MB video file across to my NAS using good old copy & paste and the average is write/transfer rate is:

 


 

 

 

 

 

What gives? Why does the LAN utility give such "inflated" results?

 

 

 

 

 

 

 

 


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  Reply # 1649330 11-Oct-2016 16:46
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You're barking up the wrong tree if you want to apply logic to Windows file transfer speeds.




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  Reply # 1649332 11-Oct-2016 16:49
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Er...ok...woof?


 
 
 
 


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  Reply # 1649528 11-Oct-2016 23:30
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woodson:

 

What gives? Why does the LAN utility give such "inflated" results?

 

 

Presuming that you have a 1 gigabit/s Ethernet connection to the NAS, the read speed of 203 Mibytes/s is impossible - that is 1624 Mibits/s, way faster than your Ethernet can do.  So clearly that number is just wrong.  However, LAN speed tests will often be much faster than the file copy speeds, as the LAN speed test does not use the hard disk, so is not slowed down to the speed of the disk transfers.  It is only fairly recently that hard disks have become faster than gigabit Ethernet, and your NAS box is not likely to have such fast disks.  And lots of NAS boxes seem to have rather slower disk speeds than the rated speeds of the drives, as they have underperforming CPUs or bad software.  And the protocol used for the file copies also matters, and whether it has been tuned properly.  Some protocols have higher LAN overheads than others.  The protocol used for LAN speed testing is likely to be minimal, compared to that used for file transfers.

 

And then there is the packet size used - in a LAN, if you want to speed things up significantly it is possible to use much larger packets such as 9000 bytes or even larger, if your Ethernet cards support it and if their drivers support it and if the operating systems support it.  That cuts down on the protocol overheads.  But mixing LANs with large packets enabled with access to the wider Internet where only the original 1500 byte maximum packet size is supported causes all sorts of problems (especially with Windows boxes), so it is rare to be able to get that working.

 

Also a problem when doing file copies to test speeds is caching.  Most modern operating systems use any RAM that is not in use for other things as file cache.  So if you copy the same file more than once, the second copy operation will likely find lots of that file, if not all of it, available in RAM cache, and will not have to read the disk.  At the other end, when writing a file, once all the file is received at the far end and is in RAM cache, the signal may well be sent back to the receiving end that the copying is done, when in fact it will take quite a while longer for the RAM cache to be written to disk.  To complicate things further, hard disks also have their own cache.

 

Benchmarking is a very difficult thing to get right, even for experts.  There are many more complicating factors.

 

 


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  Reply # 1650674 13-Oct-2016 20:29
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do a 1 gigabyte file and see what speed you get?

 

 




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  Reply # 1650935 14-Oct-2016 11:29
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1Gb file via LAN Utility:

 

 

 

 

And a dummy 1GB file via standard Windows file transfer:

 

 

 


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  Reply # 1650944 14-Oct-2016 11:38
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fe31nz is 100% correct.

 

Slow transfers to a NAS box are usually a combination of underpowered CPU, badly written software and/or crappy disks.

 

Then add in all the permutations of IO on your source PC, with AV software, CPU etc and you get a fun time.

 

 




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  Reply # 1650963 14-Oct-2016 11:46
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NAS box has a second gen i5 and 8GB of RAM.  HDDs are WD Reds and OS is FreeNAS

 

 

 

My PC has a sixth gen i5, 16GB RAM, 850 Evo SSD, gigabit Ethernet built into the mobo.

 

 

 

Could the fact that the two are connected via powerline adaptors (TP Link TL-PA8010, 1200Mbps kit) be the likely factor? 


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  Reply # 1650970 14-Oct-2016 11:52
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woodson:

 

 

 

Could the fact that the two are connected via powerline adaptors (TP Link TL-PA8010, 1200Mbps kit) be the likely factor? 

 

 

Perhaps it is but you can rule it out by connecting the NAS/PC directly with a CAT5/6 cable and see if you get a different result.

 

 


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  Reply # 1650971 14-Oct-2016 11:53
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Probably. Any way you can check it through just a switch?

 

That is very slow, even for 100Mb (let alone Gb). 1.31 MB/s is about 10Mb/s. Something is wrong at one end of your transaction.




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  Reply # 1650974 14-Oct-2016 11:56
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Bit of a faff as my main PC is in an external office and NAS is in the lounge. Might have to take the PC and a monitor inside and hook 'em up to the NAS, as you guys suggest.


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  Reply # 1650989 14-Oct-2016 12:13
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woodson:

 

Bit of a faff as my main PC is in an external office and NAS is in the lounge. Might have to take the PC and a monitor inside and hook 'em up to the NAS, as you guys suggest.

 

 

Take a look at this review, they can't get one to go above 115Mbps. Similar to wifi routers, test lab results show wow, real life results usually yield wow/10.




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  Reply # 1650996 14-Oct-2016 12:21
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Yeah I remember seeing that review. I get better numbers than that

 

 

 

 

 

 

But have seen up to 400+ Mbps...but often lower than that, even double digits, so it swings in data roundabouts.  :)

 

 


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  Reply # 1651015 14-Oct-2016 12:34
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woodson:

 

Bit of a faff as my main PC is in an external office and NAS is in the lounge. Might have to take the PC and a monitor inside and hook 'em up to the NAS, as you guys suggest.

 

 

A 20m, 30m or longer network patch cable would be useful .. handy for troubleshooting EOP and Wifi issues ..





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  Reply # 1651041 14-Oct-2016 13:29
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woodson:

 

Could the fact that the two are connected via powerline adaptors (TP Link TL-PA8010, 1200Mbps kit) be the likely factor? 

 

 

YES! Those things are more of a lie than wifi gear for rates.Your testing app is just giving you BS numbers. Chances are it is just hitting the local cache on the PC. I see the same thing copying across the lan, starts off at 200+ megabytes a second then flatlines at 110 or so after the cache is filled up, and a massive pause at the end of the transfer while the write cache is still being written out.





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  Reply # 1651078 14-Oct-2016 13:58
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woodson:

 

1Gb file via LAN Utility:

 

 

 

 

 

 

 

 

 

I would conclude your test is fundamentally flawed. It is showing you speeds circa 8Gbps, across a 1Gbps LAN. Can you test with a UNC path as the destination, isntead of a mapped drive? I suspect it is doing some unusual caching that means it is only testing throughput to local memory cache and not the actual network transfer.





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