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I recently built a NAS box on top of ubuntu server. I have an average transfer of about 10mb/sec over gigabit wire to my computer. I was hoping you guys could give recommendations on how to pinpoint where the bottleneck is in this system. To my knowledge the router is only rated at 100mb/sec, and so are the nics (both server, and client), but shouldn't my files be transferring faster then 10mb/sec? I made sure to shutdown all other traffic when getting the 10mb/sec baseline.


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When I experience crazy connectivity issues, I usually check duplex settings on devices before anything else. – Fergus Jun 27 '11 at 2:20
What is your disk configuration? one drive will behave much different than a raid5 or raid10 array. – Brian Jun 27 '11 at 3:52
When they are both set to half duplex 100mbs, they run at 10 mbs, but when set at full duplex, they run at like 30kbs. – Ben Jun 27 '11 at 4:09
@Brian, right now just drives, I plan on putting a zraid on (with 3 terabyte drives), but held off until I could diagnose the speed issue (don't want to make it worse, if it is the drives). – Ben Jun 27 '11 at 4:09
Note that transferring a 100MB file over a 100mb network should take about 15-20 seconds (since it will transfer at about 8MB/sec ... 100mb speeds are rarely maintained). Just want to make sure you did not mix up your bits and bytes =) – Beep beep Jun 27 '11 at 4:53
up vote 1 down vote accepted

Was this for transferring a single file? Also, is this performance consistent across multiple client machines? For testing, your best test is to take a very large file (500MB or so) and transfer it.

Here is how I would test it:

  • Borrow a laptop for testing, should be different O/S from your current machine(s) if possible
  • Send a large file from borrowed laptop to your current test machine (and vice versa)
  • Send a large file from borrowed laptop to NAS (and vice versa)
  • Send a large file from current test machine to NAS (and vice versa)

If all of the above yield 10Mb speeds, the issue is your router. If the performance is only slow when transferring to/from the NAS, then the issue is your Ubuntu setup (I'd guess network config, bad driver, etc). If the issue is only from your current test machine, but the borrowed one works fine, then it's likely a driver issue or config (e.g. duplex setting).

Hope this helps

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Thank you, one thing I could think of is maybe an issue with right performance on the drives, but I will try that, thanks – Ben Jun 27 '11 at 4:12
Seems like that did it, switching the routers helped a lot – Ben Jun 27 '11 at 4:54

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