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Author Topic: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec  (Read 27080 times)

EBS

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Hello All,

I am struggling now to get my data off of my DNS-323. I just ordered another one. I hope that when I plug in the new one, my network will spring back to life.

For about two years I gotten used to fast transfers between my two machines and my NAS. I use a lot of large virtual hard disks, and also Acronis disk images. I stash them on the NAS. Transfer was always more than 100 Mb/sec.

Suddenly, four days ago, moving a large file took hours instead of minutes. I am worried that the NAS is failing so I have been moving data off of it..... slowly.

Now when I test with LAN Speed Test (1.1.5 Totusoft), I get 8.1 Mb/sec

Yesterday I replaced all three cables with new cat6. The switch is a Netgear GS605. I have a laptop, a desktop and the DNS-323. The NAS is set to gigabit only. Both computers are gigabit. Transfer laptop to desktop is 110 Mb/sec.

I am recovering family photos now. Transfer is almost complete. Moving 48.5 GB of data has taken just over 14 hours.

My switch tells me that the NAS has a gigabit connection. I have enabled jumbo frames and I have tried various MTU sizes.

The strange thing is that this all ran very differently up until 4 days ago. I did upgrade to 1.09, but I also downgraded as a test two days ago, with no apparent affect. I am back to 1.09 now.

Any ideas?



EBS


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fordem

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #1 on: April 20, 2011, 08:41:36 AM »

There are a couple of other things that can impact transfer speed - remember you're moving data from disk to disk, not just across a network - so the time taken to both read from & write to the disks frequently has an impact.

If the disks at either end are fragmented, you will see a drop in throughput.

File sizes also have an impact - transferring 20GB worth of 3MB files takes a heck of a lot longer than transferring 20x3GB files - especially when writing to the DNS-323
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dosborne

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #2 on: April 20, 2011, 10:10:23 AM »

Anti-virus scanning is often a factor too. Maybe there was an update or you changed some settings?
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3 x DNS-323 with 2 x 2TB WD Drives each for a total of 12 TB Storage and Backup. Running DLink Firmware v1.08 and Fonz Fun Plug (FFP) v0.5 for improved software support.

EBS

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #3 on: April 20, 2011, 10:29:38 AM »

No changes that I can identify. Also, the behavior is the same between the NAS and desktop, and NAS and laptop.

I just completed another test:
A single 307MB file took 28 minutes to copy over. That's 1.4 Mb/sec.

It feels like something is broken. Failing NIC in the NAS?

I will be very curious to find what happens when I plug the same drives into my new DNS-323.

For now many thanks to Wigg and others who posted about [http://www.fs-driver.org/]

I have plugged one of the drives directly into my desktop and I am backing up all data.


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JavaLawyer

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #4 on: April 20, 2011, 11:30:55 AM »

Did you recently increased the volume of data stored on the unit or has that remained relatively constant before and after the issue surfaced?  Is the HDD close to full?
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EBS

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #5 on: April 20, 2011, 01:51:34 PM »

I have 2 500GB drives

Volume_1 - RAID 1, ~400MB, 355MB used
Volume_2 - JBOD, ~200MB, 177MB used

I don't think that the volume of data has changed much recently.
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TJ

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #6 on: April 20, 2011, 06:39:21 PM »

... Wait, you were getting 100mb/s or 100MB/s? 100 megabit works out to 12.5 megaBYTES.

These boxes were advertised as having transfer rates somewhere between 20 and 25 MB/s.

Do a speedtest using nas tester:

http://www.808.dk/?code-csharp-nas-performance

on a 400MB file I only get 9.55 average write, but a 20.28 average read. This is without jumbo frames.
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Steve Pitts

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #7 on: April 22, 2011, 08:35:55 AM »

File sizes also have an impact - transferring 20GB worth of 3MB files takes a heck of a lot longer than transferring 20x3GB files - especially when writing to the DNS-323
This one made me smile when I first read it, since read verbatim it is comparing transferring 20GB of small files with 60GB of large files, but in reality that turns out to be the case (at least when it comes to the DNS323) since my experiments suggest that it takes more than six times longer to transfer 20GB of 2MB files compared with 20GB of 2GB files. When I repeat the experiment from PC to PC I see ratios closer to 2.5 times slower, with the speed of the receiving machine (not unsurprisingly) being the main factor in determining the exact ratio.

Just for the record, here are the details of those bits of my setup that participated:

  • cheapie gigabit switch (Tenda TEG1008)
  • CAT6 cabling to all gigabit devices
  • DNS323 (as per my sig)
  • Dell GX620 (2.8GHz Pentium D, 3GB RAM, UDMA100 320GB WD HD, gigabit on motherboard identified as Broadcom NetXtreme 57xx in Device Manager, Windows XP 32-bit)
  • Toshiba TECRA A10 laptop (2.53GHz Core 2 Duo, 4GB RAM, SATA150 250GB Hitachi HD, Intel 82567LM gigabit on board, Windows 7 Enterprise 32-bit)
  • CryoPC Nemesis (i7 2600K overclocked to 4.8GHz, 8GB RAM, SATA300 1TB Samsung F3 HD, Realtek RTL8111E gigabit on motherboard, Windows 7 Pro 64-bit)

NOTE that, other than the NAS, all disk partitions are NTFS.

Current tests were all run on the Dell box (although I intend to repeat them from the Cryo, not in the least because I'm still not convinced that I'm getting the full possibilities talking between Win7 and XP). The data transferred consisted of two flat directories, one with 10 files of 2,146,566,144 bytes and the other with 10240 files of 2,096,232 bytes. The machines at either end of the transfer were not in use for anything else whilst the transfers took place and there was no other significant traffic on the network at the time:

From Dell to NAS, large files took 0:21:18.98 (16.78MB/s) whilst small ones took 2:14:37.14 (2.66MB/s)

From Dell to laptop, large 0:13:57.82 (25.62MB/s), small 0:38:51.27 (9.21MB/s)

From Dell to Cryo, large 0:14:37.69 (24.46MB/s), small 0:37:20.32 (9.58MB/s)   

The slower large file transfer speed to the Cryo (compared to the laptop) surprised me somewhat, but I intend to repeat all of these tests a couple of times, so hopefully it will become apparent whether this is normal or a blip.

I also tested locally on those machines that had multiple hard drives:

Cryo (SATA150 Maxtor 160GB as the target), large 0:06:39.32 (53.76MB/s), small 0:08:29.05 (42.17MB/s)

Dell (SATA300 Seagate 160GB), large 0:17:30.98 (20.42MB/s), small 0:26:03.35 (13.73MB/s)

Not sure exactly what conclusions should be drawn from all of the above, and I was quite surprised that the Cryo did such a speedy job with the small files compared to the large, but the one thing that does jump out is that the DNS323 does a far worse job writing small files, as fordem intimated.
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Cheers, Steve

Running a DNS-323 Rev. C1 with FW 1.10b5, fun_plug 0.5 and 1 Western Digital WD20EARS-00MVWB0, 4K aligned by 1.10FW, in Standard mode as a single volume

fordem

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #8 on: April 22, 2011, 03:06:33 PM »

This one made me smile when I first read it, since read verbatim it is comparing transferring 20GB of small files with 60GB of large files, but in reality that turns out to be the case (at least when it comes to the DNS323) since my experiments suggest that it takes more than six times longer to transfer 20GB of 2MB files compared with 20GB of 2GB files. When I repeat the experiment from PC to PC I see ratios closer to 2.5 times slower, with the speed of the receiving machine (not unsurprisingly) being the main factor in determining the exact ratio.

Steve - that is actually a typo - it's not what I meant to say, but as you discovered, it is not an incorrect statement.

By the way - try defragmenting the drives on the Dell and see what it does for the local transfer.
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EBS

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #9 on: April 24, 2011, 07:44:41 AM »

... Wait, you were getting 100mb/s or 100MB/s? 100 megabit works out to 12.5 megaBYTES.

These boxes were advertised as having transfer rates somewhere between 20 and 25 MB/s.

Do a speedtest using nas tester:

http://www.808.dk/?code-csharp-nas-performance

on a 400MB file I only get 9.55 average write, but a 20.28 average read. This is without jumbo frames.

Thank you very much, all of you who are trying to help.
To clarify, In my post, I use [Mb = megabit] and [MB = megabyte]. I hope that this is correct usage. Sorry if it confuses.
Thank you for the link to the NAS speed tester.
My new DNS-323 is here. I have configured it and I have installed a single 500GB drive (Seagate ST3500630AS). The switch tells me that the NAS has a 1000Mb connection.
I have a problem. It must not be with the NAS device. In my first test, I moved a single 102MB file to the NAS using a Windows Explorer copy/paste. It took the transfer 1 hour 45 minutes to complete.
I am testing now with the NAS Performance Tester 1.2.
See log:
NAS performance tester 1.2 http://www.808.dk/?nastester
Running warmup...
Running a 400MB file write on drive N: 5 times...
Iteration 1:     16.05 MB/sec
Iteration 2:     15.78 MB/sec
Iteration 3:     16.04 MB/sec
Iteration 4:     15.95 MB/sec
Iteration 5:     16.43 MB/sec
------------------------------
Average (W):     16.05 MB/sec
------------------------------
Running a 400MB file read on drive N: 5 times...
....... and this is where it still sits after waiting 35 minutes

So writes were very fast in this test (I could certainly live with 16MB/sec). The first of 5 reads has not yet completed.
I believe that during a Windows Explorer copy, the OS both writes and reads the destination drive.

What is my bottleneck? I have disabled my anti-virus on-access scan.
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EBS

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #10 on: April 24, 2011, 08:04:32 AM »

NAS performance tester really make it look like I have a read problem:

It finally completed its first 400MB file read:

NAS performance tester 1.2 http://www.808.dk/?nastester
Running warmup...
Running a 400MB file write on drive N: 5 times...
Iteration 1:     16.05 MB/sec
Iteration 2:     15.78 MB/sec
Iteration 3:     16.04 MB/sec
Iteration 4:     15.95 MB/sec
Iteration 5:     16.43 MB/sec
------------------------------
Average (W):     16.05 MB/sec
------------------------------
Running a 400MB file read on drive N: 5 times...
Iteration 1:     0.19 MB/sec

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fordem

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #11 on: April 24, 2011, 05:28:49 PM »

I know I've suggested this before - so forgive for being a nag - have you looked at the other side of the connection?

You've swapped out the DNS-323 and pretty much proven that it's not the problem.

Have you tried defragmenting the disk(s) in the PC, have you tried a new network cable between the router & the PC, have you looked at the NIC and/or it's drivers?
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mihies

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #12 on: April 27, 2011, 11:16:14 AM »

I am seeing average write speed 16.79MB/s and read speed 18.97MB/s. That's still fairly slow for a gigabit connection using a single 750GB disk - no raid.

I'll try changing network cable and try it again.
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fordem

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #13 on: April 27, 2011, 01:06:01 PM »

I am seeing average write speed 16.79MB/s and read speed 18.97MB/s. That's still fairly slow for a gigabit connection using a single 750GB disk - no raid.

I'll try changing network cable and try it again.

What you need to understand is that anything over 100mbps (call it 10MB/sec to account for overhead and make it convenient) is gigabit - and - not because you have a pipe capable of flowing 1000mbps, means you'll see anywhere close to that.

Changing the cable probably won't help.
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mihies

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Re: Sudden Drop in Transfer Speed - Was > 100Mb/sec.... Now about 8Mb/sec
« Reply #14 on: April 27, 2011, 01:45:26 PM »

I am getting over 50MB/s to another server on the same network easily. Call it what you want :-)
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