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Author Topic: Highest disk transfer performances: who/how much/how ?  (Read 14051 times)

AKFubar

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #15 on: February 16, 2010, 01:32:59 PM »

Using net meter, I'm getting on the average of 20-22Mbps transferring a single 4gb file to the NAS

I agree that units used can be confusing.  However is not unreasonable to presume beefy314 is referring to Mega Bytes since he is referring to "file" transfers and files are usually measured in bytes/megabytes etc..   :)
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tom-p

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #16 on: February 16, 2010, 02:12:33 PM »

Industry standard measurements.

Disk transfer rates/speed - MB/sec (megabytes)
LAN/WAN transfer rates/speed - Mb/sec or Mbps (megabits)

1 Mb = 0.125 MB
or
1 MB = 8 Mb

Therefore 1Gig = 1000Mb = 125 MB, your Gig connection maximum theoretical speed is 125MB/s, account for packet/protocol overhead your down to 100MB/s, account for practical throughput your down to 85MB/s, then account for OS/NIC vendor inefficiency, CPU overhead etc you may not ever exceed 65MB/s.

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fordem

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #17 on: February 16, 2010, 03:23:36 PM »

I agree that units used can be confusing.  However is not unreasonable to presume beefy314 is referring to Mega Bytes since he is referring to "file" transfers and files are usually measured in bytes/megabytes etc..   :)

Unfortunately - and a perusal of the threads in this forum that discuss the speed (or lack therof) of the DNS-323 will bear witness - presumptions as to what a lay person means are an exercise in futility.

I now invite you to use the search function and see for yourself.
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fordem

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #18 on: February 16, 2010, 03:51:25 PM »

Running a 2000MB file write on drive s: twice...
Iteration 1:     17.73 MB/sec
Iteration 2:     17.83 MB/sec
------------------------------
Average (W):     17.78 MB/sec
------------------------------
Running a 2000MB file read on drive s: twice...
Iteration 1:     29.02 MB/sec
Iteration 2:     25.34 MB/sec
------------------------------
Average (R):     27.18 MB/sec
------------------------------

Interesting - your results go in the opposite direction to mine - maybe this relates to your jumbo frame size.

If you have the time and the interest (and your network can support it) - maybe you might like to try a larger frame size.  I'll warn you though - this can become an exercise in "one-up-man-ship" - merely a competition to see who can generate the highest numbers, because the best frame size would be the one that maximizes throughput with the file sizes you use on a day to day basis.
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fordem

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #19 on: February 16, 2010, 03:58:56 PM »

Industry standard measurements.

Disk transfer rates/speed - MB/sec (megabytes)
LAN/WAN transfer rates/speed - Mb/sec or Mbps (megabits)

1 Mb = 0.125 MB
or
1 MB = 8 Mb

Therefore 1Gig = 1000Mb = 125 MB, your Gig connection maximum theoretical speed is 125MB/s, account for packet/protocol overhead your down to 100MB/s, account for practical throughput your down to 85MB/s, then account for OS/NIC vendor inefficiency, CPU overhead etc you may not ever exceed 65MB/s.



Thank you Tom - I see some "accepted rules of thumb" coming into play here.

I have two difficulties with your post ...

- the first is that it approaches a discusion on disk transfer performance (please refer to the title of the thread) from a network throughput angle and as such completely ignores the bottlenecking that can occur at the disk interfaces and the perfomance degradation that can be caused by purely disk related issues, such as fragmentation.

- the second is that it suggests that disk transfer speeds of as much as 65MB/sec can be acheived by a NAS on a gigabit network, and this, whilst not incorrect, is based upon an invalid assumption (that of the available processor performance), and in fact is what has led to the large number of discussions on disk transfer speeds as it relates to the DNS-323 - you're now giving false hope to all those who read here.

I've had my DNS-323 for over three years and I know without a doubt that it's maximum performance does not even remotely approach 65MB/sec - a memory to memory transfer that completely ignores the disk subsystem can barely crack 500 mb/sec.
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tom-p

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #20 on: February 17, 2010, 10:04:22 AM »

Hi foredem, maybe I should have been a little more clear to say that my previous post was not specific to the DNS-323 but to data transfer speeds over GigE LANs in general.  I was trying to set expectations around the fastest possible speeds over GigE network connections regardless of NAS device.  Higher end NAS systems that can support faster disks, R5 or R10 over numerous spindles, with built in caches will likely not exceed 65MB/s.

Agree that CPU, interfaces and fragmentation play a factor in data throughput and given the home use nature of the DNS-323 and 2 disk limit people should not expect 65MB/s.  I'll leave the actual performance data for the DNS-323 to those on this thread that are benchmarking with the various utilities available.

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fordem

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #21 on: February 17, 2010, 10:56:09 AM »

How about this  ;) ...

1 Mb = 0.125 MB
or
1 MB = 8 Mb

Therefore 100Mb = 12.5 MB, your 100mbps connection's maximum theoretical speed is 12.5MB/s, account for packet/protocol overhead your down to 10.0MB/s, account for practical throughput you're down to 8.5MB/s.

Anything faster than that may be considered as gigabit performance - it may be less than you anticpated (or were hoping for) but, since it is faster than 100 mbps can deliver, it is, nevertheless, gigabit performance.

What I'm actually trying to do here is to set an expectation level because I've noticed that users seem to expect figures in the 65MB/sec vicinity (or at least significantly higher than the DNS-323 delivers).

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can80an

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #22 on: February 17, 2010, 03:27:17 PM »


What I'm actually trying to do here is to set an expectation level because I've noticed that users seem to expect figures in the 65MB/sec vicinity (or at least significantly higher than the DNS-323 delivers).


I'd be thrilled to death to get transfer speed anywhere close to what I get on PC to PC transfer across my gigabit network.  Using NASTester on my newly purchased DNS-323 I am getting 17.77 write and 27.45 read.  I also have a Linux server set up which I can get 47.55 write and 50.29 read.

Reading the specs before buying the unit gave me the impression that I would be getting speeds at around what I was already getting.  Am I disappointed?  Sure I am, but I have no intention of taking the unit back.  It's a great little unit and does pretty much everything I need it to do.
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fordem

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #23 on: February 17, 2010, 03:40:56 PM »

can80an

First - I am not entirely certain I understand you ...

Reading the specs before buying the unit gave me the impression that I would be getting speeds at around what I was already getting.

Does this mean you had the impression you'd be getting the same speeds you were "PC-PC"?  Because if it does, I'd like to know exactly where you read those specs.

It's been a number of years since I dumped the box my DNS-323 came in, but as far as I can recall, the spec on the box didn't promise the speeds you're reporting now - compared to my best results I'd say you're doing pretty good, and are unlikely to see anything significantly faster.
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can80an

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #24 on: February 17, 2010, 05:09:33 PM »

can80an

First - I am not entirely certain I understand you ...

Does this mean you had the impression you'd be getting the same speeds you were "PC-PC"?  Because if it does, I'd like to know exactly where you read those specs.

Nope, sorry I wasn't clearer, all I meant was that when I saw it had a gigabit ethernet port I 'assumed' that I would get the speed I was getting across my network.  I don't recall reading any spec that quoted transfer rates, but this is what my computer vendor has on their web site:

Ports
1 x 10/100/1000 Gigabit Ethernet Port
1 x USB Print Server Port
Power

Had I come here first my initial expectation would definitely been different.  From the comments I've read, I do understand my transfer rates are about the best I can get and I'm OK with that or I would have already returned the unit.

Didn't mean to get off on the wrong foot with my first post ...  :-)
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fordem

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #25 on: February 17, 2010, 06:16:59 PM »

Thanks for the clarification.

If I recall correctly (it's been over three years), when I ordered mine I did have some idea of what the advertised speed was, and I know there were some figures quoted on the box, but with the usual "upto" disclaimer of course.

At that time, jumbo frame was not supported, and with it's addition, the claimed speeds were not only delivered, but easily surpassed.
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can80an

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #26 on: February 17, 2010, 07:48:06 PM »

If I recall correctly (it's been over three years), when I ordered mine I did have some idea of what the advertised speed was, and I know there were some figures quoted on the box, but with the usual "upto" disclaimer of course.

At that time, jumbo frame was not supported, and with it's addition, the claimed speeds were not only delivered, but easily surpassed.

Hmm, interesting you mention 'figures quoted on the box', I just checked mine and it does indeed quote some figures of 'up to 23MBps-Read and 15MBps-Write'.  I'm almost bang on those numbers.

My PC network card supports 1500, 4000 and 9000 jumbo packets.  I've tested all of them and found 4000 gives me the best performance.
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fordem

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #27 on: February 18, 2010, 04:32:38 AM »

Hmm, interesting you mention 'figures quoted on the box', I just checked mine and it does indeed quote some figures of 'up to 23MBps-Read and 15MBps-Write'.  I'm almost bang on those numbers.

Now we're getting someplace - these are D-Link's stated numbers and most of us know that what the "up to" really means is - you should expect less.  I think those are the old "pre jumbo frame" numbers and the addition of jumbo frame is what allows you to get where you are - 15~20% over.

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AKFubar

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Re: Highest disk transfer performances: who/how much/how ?
« Reply #28 on: February 18, 2010, 05:51:37 AM »

Hmm, interesting you mention 'figures quoted on the box', I just checked mine and it does indeed quote some figures of 'up to 23MBps-Read and 15MBps-Write'.  I'm almost bang on those numbers.

My PC network card supports 1500, 4000 and 9000 jumbo packets.  I've tested all of them and found 4000 gives me the best performance.

Yup same here.  I'm pretty sure I have squeezed just about all the speed that I can from my current setup. :)
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