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Gigabit network (Read 4275 times)
Brian
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Gigabit network
Jan 11th, 2010 at 12:11am
 
I've finally escaped from wireless networking and computer to computer transfer speeds of 1 MB/sec. We've had the house cabled with Cat 6 Ethernet cable and I've installed gigabit NICs and connected a gigabit switch to my router. My kids have old computers with IDE HDs, less than 80 GB in size so I guess their HDs are the speed bottleneck. We see speeds of 25 MB/sec when copying large files over the network. Much nicer than 1 MB/sec. I think it would be even faster with SATA 2 HDs at both ends but what speeds do you actually see with fast HDs and a gigabit network?

 
 
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NightOwl
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Re: Gigabit network
Reply #1 - Jan 11th, 2010 at 9:32am
 
@
Brian

Quote:
what speeds do you actually see with fast HDs and a gigabit network?

Sorry, don't have an answer for that question--hopefully someone else does!

Quote:
I've finally escaped from wireless networking and computer to computer transfer speeds of 1 MB/sec.

Interesting!  Usually the talk is all about wireless, wireless, wireless.....!  I always use wired if I can--it's faster!!!!  But, I don't have a *gigabyte* network, just 10/100.  And, since my other computer died over a year ago, I've not been networking at all--wireless or wired!

But, I did get a new cable modem recently--my original one dated back to the dinosaur days of around 2000 or so--I got about 1/3 increase in internet speeds by doing that!

Quote:
We see speeds of 25 MB/sec when copying large files over the network. Much nicer than 1 MB/sec.

25 X increase!--yes--much nicer!
 

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MrMagoo
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Re: Gigabit network
Reply #2 - Jan 11th, 2010 at 5:25pm
 
Brian wrote on Jan 11th, 2010 at 12:11am:
I think it would be even faster with SATA 2 HDs at both ends but what speeds do you actually see with fast HDs and a gigabit network?

Well remember that network speeds are measured in bits, why everything on your computer is measured in Bytes.  So, the therotical maximum of a 1Gb/s network is 1,000 / 8 = 125 MB/s.

The network can and will go that fast as long as your switch can handle it.  There is a little bit of overhead in the networking protocols, but I think you should be able to see at least 100MB/s transfer speeds. 

The thing is that even 2 SataII HD's in a RAID0 array aren't that fast in real world read speeds.  Maybe if you raided some SSD's together you could get read speeds that fast, but that's talking some major $.  Realistically, your HD's are almost always going to be slower than your new, shiny network.  Think of it as good news - you'll never be waiting on the network!

 
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Brian
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Re: Gigabit network
Reply #3 - Jan 11th, 2010 at 5:47pm
 
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MrMagoo wrote on Jan 11th, 2010 at 5:25pm:
There is a little bit of overhead in the networking protocols, but I think you should be able to see at least 100MB/s transfer speeds.

That's why I'd like some real world figures. I've seen posts where people say their maximum speed is 35 MB/sec. I've never seen a figure higher than that. Any chance of you doing a test?

I can transfer large files at 100 MB/sec between my internal HDs but the kids' computers are much slower.
 
 
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MrMagoo
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Re: Gigabit network
Reply #4 - Jan 13th, 2010 at 6:51pm
 
Brian wrote on Jan 11th, 2010 at 5:47pm:
Any chance of you doing a test?

I have done real-world tests and the numbers I gave you reflect them.
 
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Brian
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Re: Gigabit network
Reply #5 - Jan 13th, 2010 at 7:04pm
 
Many thanks for doing those tests. I'm delighted with the results and we can look forward to much faster transfer rates when we upgrade the kids' computers. In the distant future.

 
 
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Brian
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Re: Gigabit network
Reply #6 - Jan 14th, 2010 at 5:11pm
 
I thought of a test I could do. You will recall my transfer rate from the kids' computers to mine was 25 MB/sec. I copied large files from computer 1 to my HD0 and from computer 2 to my HD1. The combined transfer rate was 50 MB/sec. I'm impressed.
 
 
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Re: Gigabit network
Reply #7 - Feb 9th, 2010 at 2:43am
 
I upgraded to Gigabit several years ago and it's been great. I usually get 25-50MB/sec. and I've seen bursts up to around 70MB/sec.

I'm not a networking expert, but I think it depends a lot on the NIC, the drivers, and the settings (Jumbo Frames, etc.). I notice speed differences between different computers, but I've never bothered to pin down the settings. Overall, it's faster than USB 2. At 50MB/sec., the network utilization is only around 45% so I think it could probably go faster.

I've also seen it drop to a crawl. For example, the other day I did an IFL backup to my WHS and the backup was fast. However, when it switched to the validation, it slowed to several MB/sec. I ended up stopping it and doing the validation from Windows.

My newer Seagate drives can sustain around 120MB/sec. in single drive mode. I have two in RAID 0 and they'll do 250MB/sec. with a 220MB/sec. average. Very noticeably faster than the older drives I have.

Paul
 
 
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MrMagoo
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Re: Gigabit network
Reply #8 - Feb 9th, 2010 at 7:44pm
 
MudCrab wrote on Feb 9th, 2010 at 2:43am:
I've also seen it drop to a crawl. For example, the other day I did an IFL backup to my WHS and the backup was fast. However, when it switched to the validation, it slowed to several MB/sec. I ended up stopping it and doing the validation from Windows.

As we were discussing, this limitation is on HD and CPU, not on the network.  You network should be capable of > 100MB/sec.  Your NIC's and drivers are likely faster than your PCI bus, HD, etc.
 
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Re: Gigabit network
Reply #9 - Feb 9th, 2010 at 8:44pm
 
MrMagoo,

The "crawl" to which I was referring is definately network related. I've had it happen with several imaging programs (in and out of Windows), both on validating. The computers are fast (Core2 Duo 2.67GHz and i7 2.8Ghz) and both running RAID 0 SATA-II. There's no way either the CPU or the drives are being stress with a 2-6MB/sec. transfer rate.

I think the problem actually has to do with how the reading/accessing is done by the program. Maybe it's reading small packets on validation and the overhead kills it. Maybe it's a "bad" driver. However, it's not like that in Windows doing the same validation with IFW. It may also be something specific to the WHS on those types of reads.

I have not had time to really test it out, but would like to so I could (at the very least) have a better understanding of the problem.

Network utilization has always seemed odd to me. I don't understand why it doesn't use more of the bandwidth available. Is it saving it for other connections? In Windows, I usually only get 30-50%. Rarely does it go up to around 75%. Sometimes it "sticks" at 15-20%. Sometimes I can start a transfer and it tops out around 18% and if I cancel it and start it over again, it jumps up to 40% or so and stays there. If I don't cancel it, it will stay at the lower speed.
 
 
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MrMagoo
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Re: Gigabit network
Reply #10 - Feb 10th, 2010 at 6:43pm
 
MudCrab wrote on Feb 9th, 2010 at 8:44pm:
I don't understand why it doesn't use more of the bandwidth available.

This is because, like I have said, your applications are not limited by the local network.  Your hard drives, PCI bus, even your internet connection can often be the bottle neck.  And I'm not convinced that even a RAID-0 SATA-II array can have read/write speeds of > 100 MB/s.  I have a 3-disk RAID-0 array in my file server and I can't get it above 40MB/s sustained write speed.  I think you'd need to RAID some SSD's together to get that speed.

MudCrab wrote on Feb 9th, 2010 at 8:44pm:
I've had it happen with several imaging programs (in and out of Windows), both on validating. There's no way either the CPU or the drives are being stress with a 2-6MB/sec. transfer rate.

There's no way a gigabit network is being stressed by 2-6MB/sec.  A 100Mb/s network could easily handle that.  Smaller packets do increase the realitive amount of overhead, but it is still small.  In order for 6MB/s to fill a gigabit network, you'd need about 1600% overhead.  Real world overhead is about 5-12%. 

They interesting thing here is that it always happens on validating.  It may not be the transfer rate that is stressing your HD's or CPU so much as whatever is involved in validating.  Your CPU could have to do some intensive task to validate this data, or your HD might be having trouble keeping up with the random accesses involved.  I don't know enough about the program you are using or about what validating does to give you the exact answer.

MudCrab wrote on Feb 9th, 2010 at 8:44pm:
I have not had time to really test it out, but would like to so I could (at the very least) have a better understanding of the problem.

I'm interested as well.  Please let us know if you are able to do some tests.
 
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Re: Gigabit network
Reply #11 - Feb 10th, 2010 at 8:37pm
 
The Seagate drives I'm using are the Barracuda 7200.12 ST3500418AS drives. When I first read the specs (125MB/sec.), I didn't believe it. I was really surprised that they did perform as advertised. A single one of these drives performed faster than the current RAID 0 setup I had at the time (I think it was using 7200.10 drives).

I can easily get 120MB/sec. sustained writing to these in RAID 0 and, if the circumstances are right, I've dropped 3GB on them in 15 seconds (210MB/sec.).

I'm not expecting that kind of speed over the network. What I would expect is for the speed I do get to be more consistent.

I don't think the validating is stressing the CPU or any of the drives involved, unless it's doing something really unusual. I mean, validating a file from Windows shouldn't be that much different than from WinPE as far as the CPU and the drives are concerned. With Linux involved, you know completely different drivers are being used.

I need to run tests to/from several different computers. It may be that it's the drivers on the WHS (or a configuration setting) that's actually causing the problem. I'd like to figure it out because the way it is now, I can't do the validations normally -- it just takes too long.
 
 
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Brian
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Re: Gigabit network
Reply #12 - Feb 10th, 2010 at 11:58pm
 
Some numbers from me. I just copied a 10,705 MB file from HD0 to HD1 in 115 seconds. That is a speed of 93 MB/second.

I image the kids' computers over the network. I use IFW and psexec initiated from my computer. My batch file makes their computer send the image to my computer as it is being created and then runs a Byte-for-Byte validation on the image. I find the network speed for the validation is about 10% faster than the speed for imaging.

Edit.... On reflection, the 10% increase in speed is not network related.
 
 
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