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#1 2012-04-26 20:10:12
- Whirly
- Member
- Registered: 2011-03-12
- Posts: 14
Write speed suddenly very slow...
I've had my DNS-323 for nigh on a year and it has always worked fine. It's on Firmware 1.10b5 (I think it's b5 - hard to remember).
Anyway, about a week ago I noticed that a 7.5Gb file had not transferred to the DNS properly. It existed as a directory listing at the correct size but was otherwise unusable. I decided to delete it with Win 7 but found any access to the DNS through file explorer to be almost impossible - it would spend around an hour trying to access the DNS before either giving up or finally opening the folders. Any attempt to delete the file or even the folder containing the file resulted in file explorer locking up. Consequently, I used FTP to delete the file, and since then Windows 7 file explorer has acted normally.
However, I immediately noticed a problem. While the read speed from the DNS remained normal (around 10Mb/s) the write speed had dropped to just 150Kb/s. This is true either through Windows or FTP...except...a day after I removed the offending file I did one more speed test and the write speed had gone up to 2Mb/s, which I figured I could live with. However, within a day the write speed returned to 150Kb/s. At all times the read speed has remained constant.
I have tried using the built in disk tools to run Scan Disk twice and both times it has returned "100% Success". I have no access to a Linux PC or any Linux experience so that avenue is pretty much closed to me.
I'm at the point where I'm going to have to move all of my data off the DNS and then re-format the drive in the hope it will fix the problem, but before I devote hours of my life to that, does anyone have any other ideas?
I would really appreciate any help - especially as I'm a newb to linux.
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#2 2012-04-27 07:02:23
- bjby
- Member
- Registered: 2009-02-22
- Posts: 265
Re: Write speed suddenly very slow...
In your place I would do this.
1. Rule out that this is a network issue.
install ffp, log in via telnet and copy a large file from one folder to another, is this also slow?
2. Run the ffp diskcheck/repair fsck
Guide is found here http://www.inreto.de/dns323/fsck/
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#3 2012-04-27 09:44:58
- Whirly
- Member
- Registered: 2011-03-12
- Posts: 14
Re: Write speed suddenly very slow...
Thanks for the advice bjby. Good call with ruling out the network. One question. Before I have to learn how to install is it possible to do the file copy with FTP without the data going over the network? (sorry, complete newb)
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#5 2012-04-27 16:56:38
- Whirly
- Member
- Registered: 2011-03-12
- Posts: 14
Re: Write speed suddenly very slow...
bjby wrote:
yes if the ftp-client and ftp-server are on same machine (not sure how useful this answer was for you).
Hehe. I'll try ffp and (if necessary) fsck over the weekend.
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#6 2012-04-29 13:39:35
- skydreamer
- Member
- From: At the Atlantic Coast
- Registered: 2007-01-06
- Posts: 232
Re: Write speed suddenly very slow...
Also I would confirm that the physical disks are sound. Smartctl will list the internal smart log.
smartctl -a -d marvell /dev/sda
and
smartctl -a -d marvell /dev/sdb
Parameter 5 reallocated_sector_ct should be zero.
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#7 2012-04-29 17:02:12
- fordem
- Member
- Registered: 2007-01-26
- Posts: 1938
Re: Write speed suddenly very slow...
skydreamer wrote:
Also I would confirm that the physical disks are sound. Smartctl will list the internal smart log.
smartctl -a -d marvell /dev/sda
and
smartctl -a -d marvell /dev/sdb
Parameter 5 reallocated_sector_ct should be zero.
mmm - having a "non zero" reallocated_sector_ct is not an indication of a failed or failing drive - as long as it is stable and not constantly increasing.
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#8 2012-05-01 16:06:31
- Whirly
- Member
- Registered: 2011-03-12
- Posts: 14
Re: Write speed suddenly very slow...
Ok, first of all thanks for all the help given so far.
As I'm completely new to linux I am likely to come across as pretty stupid so please forgive me in advance.
Right, the weekend was a bust but I've managed to get started this lunchtime. I've installed ffp using the instructions to switch to ssh (hopefully I've done this right!).
My initial test of copying a large file (just made a copy of the file within the same directory) went like this:
File was 360MB in size. Copy took 61 seconds. So, basic maths gives me a write speed of around 6Mbytes/s. That is obviously far higher than the 150kbytes/s I'm getting over the network. However, is this a normal copy speed for a file copy on the DNS323?
I also tried the smartctl command but got the error message: "-sh: smartctl: not found". I assume I'm doing something wrong...any (very) basic help would be appreciated.
I don't have exclusive access to the drive today so I won't be able to try fsck, and, tbh, if the HDD speed is normal then I'd rather avoid the hassle.
My final question is this: I've installed ffp and used putty to ssh in using the ip address of the DNS323. However, it is set to use DHCP to get its IP address so it changes irregularly. Will this be a problem for the SSH keys? Should I have put the DNS on a static IP?
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#9 2012-05-01 18:33:32
- bjby
- Member
- Registered: 2009-02-22
- Posts: 265
Re: Write speed suddenly very slow...
iperf is a tool for performing network throughput measurements. It can test either TCP or UDP throughput. To perform an iperf test the user must establish both a server (to discard traffic) and a client (to generate traffic).
iperf can be installed on the dns323 using optware. see (http://dns323.kood.org/howto:optware).
If you find this overly complex. You may also use the simple and raw "netcat" to test network. Netcat is installed by default ffp on dns323. Google "bandwidth netcat" for a guide.
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#10 2012-05-01 18:42:44
- Whirly
- Member
- Registered: 2011-03-12
- Posts: 14
Re: Write speed suddenly very slow...
Thanks bjby, I'll try that tomorrow.
BTW, any idea on the disk write speed? Is the 6Mbytes/s normal or slow?
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#11 2012-05-02 11:41:13
- Whirly
- Member
- Registered: 2011-03-12
- Posts: 14
Re: Write speed suddenly very slow...
OK, iperf installed on both ends and network tested on using a 10,000,000 bytes transfer (9.54Mb).
results:
0.0-152.2 sec 9.54 MBytes 526 Kbits/sec
now for some maths (probably wrong)
Yesterday I did a telnet disk copy which resulted in a 360Mbyte file taking 61 seconds to complete.
360Mbyte = 2949120 Kbits
data transfer speed (disk write) = 2949120/61 = 48346 Kbits/s
Network problem!
Last edited by Whirly (2012-05-02 12:18:14)
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#12 2012-05-02 12:17:20
- Whirly
- Member
- Registered: 2011-03-12
- Posts: 14
Re: Write speed suddenly very slow...
OK, first of all thanks to everyone for their help - especially bybj.
Looks like I've found the culprit. A switch on my network combined with a dying/flaky router. I've now replaced both and I'm back up to speed (around 10 Mbytes/s write speed).
I should have worked that out myself but the failed file transfer and problems with accessing it lead me up the garden path. I must assume the file failed to transfer because of the network problem - hence a symptom rather than the cause.
Still, a silver lining is that I now have ffp on my DNS and have taken my first step into linux! Now all I have to do is edit my fun_plug script to make the optware path permanent. I think I read that notepad/wordpad should not be used for editing linux scripts so as a last boon, does anyone have any suggestion for a good basic editor?
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#14 2012-05-03 11:06:31
- Whirly
- Member
- Registered: 2011-03-12
- Posts: 14
Re: Write speed suddenly very slow...
Thanks again bjby, notepad++ downloaded and put to use. 
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