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#1 2007-08-28 09:57:08

kuyawsadabaw
Member
Registered: 2007-08-06
Posts: 6

Why is it slow?

I've been trying to copy JPEGs from my computer to the DNS-323, but it just seems like the transfer speed is slow.

68.8GB of JPEGs in multiple directories. It's averaging around 4 MB/s (According to Windows Vista's Copy dialog window)

I tested a 1GB DVD image, and it transferred around 15 MB/s (According to Windows Vista's Copy dialog window)

My laptop has Gigabit ethernet

I have the DNS-323 and my laptop directly connected to my D-Link DIR-655 Gigabit Router. (So every hardware is Gigabit)

I wasn't doing anything else but the file transfer between my laptop and the DNS-323.

What could be wrong?

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#2 2007-08-28 11:53:09

frodo
Member
From: Stockholm, Sweden
Registered: 2007-01-17
Posts: 259

Re: Why is it slow?

Many small files is always going to be slower than transfering large files.
You get a lot of overhead when it comes to many files.

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#3 2007-08-28 12:09:02

kuyawsadabaw
Member
Registered: 2007-08-06
Posts: 6

Re: Why is it slow?

But are these speeds (4 MB/s for many small files, and 15 MB/s for >1GB contiguous file) characteristic of what people usually get?

I'm just really confused because I've seen post that indicate speeds from what i've mentioned to hundreds (~200mbps, 200 MB/s).

Maybe it's just a misuse of mbps and MB/s. I don't know, but I'd like to know if my speeds are comparable to yours (MB/s, Megabytes per seconds)?

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#4 2007-08-28 12:32:25

Emacs
Member
Registered: 2007-06-24
Posts: 110

Re: Why is it slow?

kuya...,

your 15MB/s for large files matches perfectly what I see on my DNS323.
Smaller files bring down the rates a lot indeed - due to the overhead frodo mentioned.

There is a thread here where people are comparing their transferrates:

http://dns323.kood.org/forum/t738-Surve … Rates.html

200 MB/s is something that surely cannot be reached with any device in the DNS323 priceclass.

Cheers,

Emacs

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#5 2007-08-28 15:45:22

transstilben
Member
From: Germany
Registered: 2007-06-15
Posts: 45
Website

Re: Why is it slow?

Emacs wrote:

... 200 MB/s is something that surely cannot be reached with any device in the DNS323 priceclass.

Cheers,

Emacs

With Gigabit LAN the theoretical limit lies around 120 MByte/s.  That means 200 MByte/s is nonesense. I think the author meant 200 megabit per second.


DNS-323 FW1.03, 500GB-Samsung HD, 4-port USB-Hub, Clients: Vista Home Basic 64 bit, XP-Professional

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#6 2007-08-28 15:50:18

fordem
Member
Registered: 2007-01-26
Posts: 1938

Re: Why is it slow?

kuyawsadabaw wrote:

But are these speeds (4 MB/s for many small files, and 15 MB/s for >1GB contiguous file) characteristic of what people usually get?

I'm just really confused because I've seen post that indicate speeds from what i've mentioned to hundreds (~200mbps, 200 MB/s).

Maybe it's just a misuse of mbps and MB/s. I don't know, but I'd like to know if my speeds are comparable to yours (MB/s, Megabytes per seconds)?

According to the box - up to 23MBps-Read and 15MBps-Write (183Mbps-Read and 120Mbps-Write) - I haven't paid particular attention to the read/write aspects, but the best numbers I have are 70~75Mbps on 100 Mbps ethernet and 140~150Mbps on gigabit.

Here are a couple of things to consider in your quest - this device is one end of a series of things in a chain.  The maximum throughput will only be as fast as the slowest device in the chain - whether or not your speeds are comparable to mine tells you very little, unless you know the rest of my chain.

Starting with the disks themselves.

Small files will require the drive heads to be jumping back & forth between the directory area and the actual file storage areas - are the seek times of our disks comparable?  Large files allow the head to hop from one sector to the next without thrashing - assuming that there is minimal fragmentation - but then actual transfer is limited by the interface - ATA66/ATA100/ATA133 - SATA - and the rotational speed of the disks 4200/5400/7200/10000/15000 rpm.

Network interfaces come next - are we using integrated NICs or are they in expansion slots - PCI33/PCI66 - PCI-X - PCI-E - and are the drivers optimal for the OS - I've seen cases where using Realtek drivers doubles the throughput over using Windows drivers.

Whilst it may be reassurring to know how our numbers compare - the stark reality is - the numbers don't mean much.

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#7 2007-08-28 16:10:38

dan.crouthamel
Member
Registered: 2007-08-23
Posts: 43

Re: Why is it slow?

fordem wrote:

According to the box - up to 23MBps-Read and 15MBps-Write (183Mbps-Read and 120Mbps-Write) - I haven't paid particular attention to the read/write aspects, but the best numbers I have are 70~75Mbps on 100 Mbps ethernet and 140~150Mbps on gigabit.

And just a clarification on that spec - DLink states that is is acheivable when using a RAID 0 configuration (striped)

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#8 2007-08-29 08:40:07

Speijk
Member
Registered: 2007-08-27
Posts: 36

Re: Why is it slow?

Same speed as I see. Large files over Cifs do 15000KB/s, lots of small files and the speed drops dramatically.
You might want to check the speed of your disk while doing random reads ands writes for these kand of files. It is not much better wink

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#9 2007-08-29 08:41:44

kuyawsadabaw
Member
Registered: 2007-08-06
Posts: 6

Re: Why is it slow?

OK, thanks for your replies. Seems like, my transfer rates aren't that weird after all.

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#10 2007-08-29 08:51:09

Speijk
Member
Registered: 2007-08-27
Posts: 36

Re: Why is it slow?

From another test I have read somewhere there is hardly any speed difference while using Raid0 or Raid1. Guess that aspect is not the decisive factor in the speed of the box. I assume it is to be found somewhere in the cpu that controlls the networkinterface. 18000 KB/s over ftd and 15000KB/s over smb/cifs (larger protocol overhead) might translate in similar networkspeed.

Last edited by Speijk (2007-08-30 08:41:15)

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#11 2007-08-29 15:20:15

fordem
Member
Registered: 2007-01-26
Posts: 1938

Re: Why is it slow?

Speijk wrote:

From another test I have read somewhere there is hardly any speed difference while using Raid0 or Raid1. Guess that aspect is not the decisive factor in the speed of the box. I assume it is to be found somewhere in the cpu that controlls the networkinterface. 18000 MB/s over ftd and 15000MB/s over smb/cifs (larger protocol overhead) might translate in similar networkspeed.

Can we agree on units - b/s is usually interpreted as bits/sec and B/s as BYTES/sec - so Kb/s would be Kilobits/sec and KB/s would be KiloBYTES/sec, Mb/s would be Megabits/sec and MB/s would be MegaBYTES/sec - although not strictly correct, bits/sec can be converted to bytes/sec by dividing by eight - this is done for ease of calculation, and ignores overhead such as framing, start & stop bits - in the case of serial communications and headers in the case of network communications.

There is something wrong with the units here - 15000-18000 MB/sec (MegaBYTES/sec) would be 15-18 GigaBYTES/sec or 120-144 Gigabits/sec, and 15000-18000 Mb/s Megabits/sec would be 15-18 Gigabits/sec - neither one of which is achievable with today's cutting edge hardware much less an entry level NAS such as this.

On the other hand, based on my experience - 15000-18000 KBps (KiloBYTES/sec) or 120-144 Mbps (Megabits/sec) is acheivable using this device on gigabit ethernet.

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#12 2007-08-29 15:35:34

fonz
Member / Developer
From: Berlin
Registered: 2007-02-06
Posts: 1716
Website

Re: Why is it slow?

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#13 2007-08-30 08:42:24

Speijk
Member
Registered: 2007-08-27
Posts: 36

Re: Why is it slow?

Sorry, I should re-read my post before I hit the "submit" button.
Of course it should have said KB/s !

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