Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have a server that freeqently downloads large files, the problem is every time it's downloading a file, it stops all network activety from that disk. in the output bellow you can see that network activety was at 1116 mbs and in the second output you can see that on sdc drive was write 391 and network activety was dropped to 502 mbs than after writes stops it's going up to normal, sometime it's dropping even to 60mps.

I'm wondering what's going on, because i have two other similar servers with which I don't have that problem. the only difference that i can think of, is on both of them i've centos6 and here i'm using ubuntu 12.04

Linux SDNRUUA 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:31:23 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

No writes to disk

DSK |          sda |  busy     15% | read     240 |  write      0 | KiB/r    128 | KiB/w      0  | MBr/s  15.00 | MBw/s   0.00  | avio 1.25 ms |
DSK |          sdc |  busy     14% | read     207 |  write      0 | KiB/r    127 | KiB/w      0  | MBr/s  12.92 | MBw/s   0.00  | avio 1.33 ms |
DSK |          sdf |  busy     13% | read     472 |  write      0 | KiB/r    128 | KiB/w      0  | MBr/s  29.56 | MBw/s   0.00  | avio 0.53 ms |
DSK |          sde |  busy     11% | read     391 |  write      0 | KiB/r    128 | KiB/w      0  | MBr/s  24.44 | MBw/s   0.00  | avio 0.54 ms |
DSK |          sdb |  busy      7% | read     120 |  write      0 | KiB/r    128 | KiB/w      0  | MBr/s   7.50 | MBw/s   0.00  | avio 1.17 ms |
DSK |          sdd |  busy      6% | read      72 |  write      3 | KiB/r    128 | KiB/w     12  | MBr/s   4.50 | MBw/s   0.02  | avio 1.65 ms |
NET | transport    |  tcpi   90171 | tcpo  186682 |  udpi       0 | udpo       0 | tcpao     27  | tcppo     48 | tcprs   1734  | udpip      0 |
NET | network      |  ipi    90172 | ipo    30192 |  ipfrw      0 | deliv  90175 |               |              | icmpi      0  | icmpo      0 |
NET | p262p1  ---- |  pcki   89893 | pcko  188178 |  si   21 Mbps | so 1116 Mbps | erri       0  | erro       0 | drpi       0  | drpo       0 |
NET | lo      ---- |  pcki     275 | pcko     275 |  si  129 Kbps | so  129 Kbps | erri       0  | erro       0 | drpi       0  | drpo       0 

write to one of the disks

SWP | tot    31.7G |  free   31.7G |              |               |              |               |              | vmcom   6.0G  | vmlim  47.3G |
PAG | scan   85374 |  steal  85374 | stall      3 |               |              |               |              | swin       0  | swout      0 |
DSK |          sdc |  busy     62% | read      30 |  write    391 | KiB/r    153 | KiB/w    508  | MBr/s   2.25 | MBw/s  97.03  | avio 2.90 ms |
DSK |          sdb |  busy     48% | read     909 |  write      0 | KiB/r    127 | KiB/w      0  | MBr/s  56.79 | MBw/s   0.00  | avio 1.03 ms |
DSK |          sde |  busy      9% | read     337 |  write      0 | KiB/r    128 | KiB/w      0  | MBr/s  21.19 | MBw/s   0.00  | avio 0.55 ms |
DSK |          sdf |  busy      7% | read     243 |  write      0 | KiB/r    128 | KiB/w      0  | MBr/s  15.19 | MBw/s   0.00  | avio 0.54 ms |
DSK |          sda |  busy      5% | read      72 |  write      0 | KiB/r    128 | KiB/w      0  | MBr/s   4.50 | MBw/s   0.00  | avio 1.28 ms |
DSK |          sdd |  busy      3% | read      29 |  write     11 | KiB/r    111 | KiB/w      4  | MBr/s   1.58 | MBw/s   0.02  | avio 1.40 ms |
NET | transport    |  tcpi   40783 | tcpo   84348 |  udpi       0 | udpo       0 | tcpao     22  | tcppo     39 | tcprs    553  | udpip      0 |
NET | network      |  ipi    40782 | ipo    14447 |  ipfrw      0 | deliv  40784 |               |              | icmpi      0  | icmpo      0 |
NET | p262p1  ---- |  pcki   40573 | pcko   84721 |  si 9857 Kbps | so  502 Mbps | erri       0  | erro       0 | drpi       0  | drpo       0 |
NET | lo      ---- |  pcki     208 | pcko     208 |  si  104 Kbps | so  104 Kbps | erri       0  | erro       0 | drpi       0  | drpo       0 |
share|improve this question
    
May be worth asking your question over at ServerFault. –  icabod Apr 4 '13 at 13:44
    
which command did you use? what does top, iotop, or some X Window performance monitor show? –  golimar Apr 4 '13 at 16:31
    
i'm using atop. i also monitored network with sar. –  teslasimus Apr 4 '13 at 16:35
    
Just looking at that "steal" time which only shows in one of your outputs. Your "servers" are VMs? Are they all on the same hardware? If they are - what are the other machines doing at the same time? –  tink Apr 4 '13 at 19:03
    
@tink They are not VMs. no, but they are all with intel cpu, motherboard and network card. they are all doing the same job, but only on this machine i have that kind of behavior. –  teslasimus Apr 4 '13 at 19:58
show 3 more comments

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.