{bb} New Version of bb-iostat.sh

[Brian Kelly <bkelly@unidata.ucar.edu>]

Hello Big Brother-ites,

I've completed a rewrite of the bb-iostat scripts, so I've called the 
new version 4.0 and uploaded it to http://www.deadcat.net .  It's been 
tested on Solaris, AIX, RedHat, Fedora Core and FreeBSD, but should 
would with any OS that has a similar vmstat command.

Improvements include:

1) Dynamic determination of the vmstat columns.  No more alarms because 
the context switching count is thought to be the scan rate.

2) More stats are watched.  The script now monitors swapped processes, 
used swap and page reclaim checks.

3) Introduction of secondary stats since high values can appear in some 
areas through normal use.  Overages here make an alarm more likely, but 
won't throw an one on their own.

Let me know of any questions or problems.

Brian


Brian Kelly wrote:

> Greetings Fellow BBers,
>
> My site uses the bb-iostat.sh script to monitor the virtual memory of 
> our our systems.  It works fairly well on our Solaris systems, but the 
> defaults constantly generated errors for an excessive scan rate on 
> Linux.  We found ourselves having to increase the scan rate from 3/6 
> to 500/1000, an alarming difference.
>
> My first question is, "Has anyone else encountered this problem?"
>
> I've done some digging and understand the issue much better.  Linux is 
> not specifically handled by the script, so it drops to the default 
> handler when reading the output from vmstat.  The problem is that 
> vmstat on Linux doesn't display a scan rate and the script grabs the 
> number of context switches instead.  This can easily go into the 
> thousands or tens of thousands on multi-processor machines and has 
> little to do with the performance of the Virtual Memory Manager.
>
> One can certainly increase the defaults with little worry because a 
> context switch takes CPU time which will be caught in other tests, but 
> it would be nice to have this fixed so there is less worry with future 
> users.  I also note that the default check by the bb-iostat.sh script 
> doesn't check the system CPU usage, something that could be easily added.
>
> I can make these changes, but I wouldn't want to step on any toes.  
> Craig Cook last modified the latest version back in 2002.  Would there 
> be any problem is I made the changes and uploaded the new version to 
> deadcat?
>
> Also, does anyone have any other thoughts on this?
>
> Thanks,
>
> Brian
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