[Linux] Network stalls

[NV]

Do the blades have local disks? Most blade servers use 3.5" laptop disk 
drives which are not fast and can get loaded quite easily. Make sure 
that DMA is enabled on the disks and the hdparm config is set for good 
performance.

If there is significant background traffic through the backplane 
Ethernet switch, it could lead to losses and force TCP to back off. This 
may also happen if you have an Ethernet switch that is acting up. Use 
the ttcp program to measure raw TCP performance between two blades 
without disk i/o in the picture.

The culprit is very likely to be disk i/o.

Regards,
Niranjan
--



Peter Capazzi wrote:
> Actually... same box.
>  
> It's a blade server. 4 blades. 3 of them I own and have identical OS' 
> installed (Suse 10).
>  
> Blade1 copy to Blade2 -> 30-40 MB/s dipped occassionally to 18... but 
> recovered well back into 30-40.
> Blade1 copy to Blade3 -> 30-33 MB/s dipped to 12-14 MB/s... doesn't 
> recover... if anyting goes down again to 5-7... then to KB's.
>  
> It's inconsistent... the time at which the bandwidth drops is 
> different each time... sometimes it gets down to 12-14 and manages to 
> stay there.
>  
>
> ------------------------------------------------------------------------
> *From:* linux-admin@flux.org [mailto:linux-admin@flux.org] *On Behalf 
> Of *Adam Glass
> *Sent:* Thursday, June 19, 2008 10:16 AM
> *To:* linux@flux.org
> *Subject:* Re: [Linux] Network stalls
>
> Are the servers in the same building, on an internal network?  Or are 
> you going over the internet?  If the latter, some ISPs are starting to 
> throttle traffic.  I thought they were only doing that to bittorrent, 
> but maybe some ISPs do it to any large file transfer.
>
> --Adam
>
>
> On Thu, Jun 19, 2008 at 9:50 AM, Peter Capazzi 
> <pcapazzi@dwcsolutions.com <mailto:pcapazzi@dwcsolutions.com>> wrote:
>
>     I'm having some trouble copying files from one server to another.
>     When scp'ing the bandwidth starts out great (33 MB/s) and then
>     within a few minutes it deteriorates to (15 MB/s), then starts
>     stalling and sputtering to finish the file.
>      
>     Has anyone seen a behavior like this before? Any suggestions to
>     resolve?
>
>