Gurus needed to diagnose severe performance degradation Post: 302350014

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Top Forums UNIX for Advanced & Expert Users Gurus needed to diagnose severe performance degradation Post 302350014 by Neo on Wednesday 2nd of September 2009 01:52:08 PM

09-02-2009

Administrator

A 1GB Ethernet connection can never approach 1GB/S because of the collision algorithm used by the Ethernet MAC protocol specification.

Sorry, I don't mean to sound like I am finger pointing, but you should have measured network performance, including throughput and latency, on both channels (old and new) before cutting over.

Ethernet does not perform well under heavy loads because of the way Ethernet works (aloha, collision, backoff) and when you add another protocol on top, the performance is worse.

A directly attached fiber channel should be far superior to ethernet, in this case. The only way to get past "finger pointing" is to build a baseline of the system before production. You have to know the maximum throughput and latency of the fiber channel and the same for the ethernet channel.

Then, you move into the next phase of testing (for a commercial applications). Without baselining, the team is always asking for trouble because you cannot know the system constraints and bottlenecks.

Normally, the network communications channel is the bottleneck. Then, the next problem is the I/O at the network interface level. These tend to perform worse than directly attached disk IO, etc.

I once worked in NYC on a TCP/IP throughput problem where people were about to get fired over the problems with production. There were finger pointing between all (network, system, and dB admins). Finally, I forced them to let me run TCP spray with the system shut down (or it was a parallel system, I can't recall), and then everyone said "Ah!! It it the network!)

Start at the network layer and work up, just the the TCP/IP protocol stack (or OSI stack, if you prefer). Without baselining, you are simply shooting in the dark and guessing. The fastest path to a solution is to take time and baseline the various critical systems, in this case, the network would be the best place to start.

Cheers.

Neo

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LEARN ABOUT DEBIAN

news::scan::poster

News::Scan::Poster(3pm) 				User Contributed Perl Documentation				   News::Scan::Poster(3pm)

NAME

       News::Scan::Poster - keep track of posters to a newsgroup

SYNOPSIS

	   use News::Scan::Poster;

	   my $poster = News::Scan::Poster->new($news_scan_article_obj);

DESCRIPTION

       This module provides a class whose objects can be used to keep track of cumulative statistics for posters to a Usenet newsgroup such as
       header volume or signature lines.

CONSTRUCTOR

       new ( ARTICLE )
	   "ARTICLE" should be a "News::Scan::Article" object or inherit from the "News::Scan::Article" class.

	   "new" performs some initialization and returns a "News::Scan::Poster" object.

METHODS

       address ( [ ADDRESS ] )
	   Returns the address of this poster represented as a "Mail::Internet" object.

	   If present, "ADDRESS" tells the object that the "Mail::Internet" object in "ADDRESS" is its address.  idea.

       attrib ( [ ATTRIBUTION ] )
	   Returns some nice attribution for this poster.

	   If present, "ATTRIBUTION" tells the object how it shall identify itself when asked.

       message_ids ( [ MESSAGE-ID ] )
	   Returns a list of Message-IDs attributed to this poster.

	   If present, "MESSAGE-ID" is added to this list of this poster's articles.

       volume
	   Returns the volume in bytes of the traffic generated by this poster.

       articles
	   Returns the number of articles attributed to this poster.

       posted_to
	   Returns a hash whose keys are newsgroup names and whose values are the number of times this poster has crossposted to the group of
	   interest and the corresponding newsgroup.

       crossposts
	   Returns the total number of crossposts this poster has sent through the group of interest.

       header_volume
	   Returns the volume in bytes generated by this poster's headers.

       header_lines
	   Returns the number of header lines generated by this poster.

       body_volume
	   Returns the volume in bytes generated by this poster's message bodies.

       body_lines
	   Returns the number of body lines generated by this poster.

       orig_volume
	   Returns the volume in bytes of original content generated by this poster.

       orig_lines
	   Returns the number of original lines generated by this poster.

       sig_volume
	   Returns the volume in bytes generated by this poster's signatures.

       sig_lines
	   Returns the number of signature lines generated by this poster.

SEE ALSO

       News::Scan, Mail::Address, News::Scan::Article

AUTHOR

       Greg Bacon <gbacon@cs.uah.edu>

COPYRIGHT

       Copyright (c) 1997 Greg Bacon.  All Rights Reserved.  This library is free software.  You may distribute and/or modify it under the same
       terms as Perl itself.

perl v5.10.1							    2000-04-13						   News::Scan::Poster(3pm)