Re: [SAGE] Lotus Domino design exercise

[Nathan Dietsch <njd@ndietsch.com>]

Hello Doug (Hanks),

Sorry for chiming in late on this, but I just saw it now.

Doug Hanks wrote:

>On Tue, 28 Dec 2004 22:06:23 -0600 (CST), Doug Hughes
><doug@eng.auburn.edu> wrote:
>  
>
>>Dtrace doesn't make applications faster, it makes debugging system
>>performance problems faster by allowing you to tie together information
>>across subsystems in a unified way (I/O, CPU, memory, truss, network, 
>>    
>>
>
>Right - it allows you to watch the application execute and you can see
>where it spends most of its time.  For things like Oracle I would
>consider it useless.  Oracle doesn't give a hoot about your dtrace
>output, unless you have a very very odd error that they aren't able to
>figure out.
>
>I could see dtrace being very useful for application development.  I
>used it when I was developing sudosh.  It's pretty much a development
>tool.  Doesn't belong in production.
>  
>

I think you are missing the point about DTrace.

Whether or not DTrace is integrated with Oracle is besides the point. 
While DTrace allows you to watch the performance or system usage of 
individual applications, ala truss(1m), it goes beyond that. DTrace 
allows you to watch the system as a whole, at a much deeper level than 
say prstat or the generic top command.

If you were debugging a problem with sudosh (which, by the way, is very 
cool), you could use either truss or DTrace as the problem is focused on 
one particular application. However, DTrace will allow you to see the 
effect on the system as a whole, which relates to Doug's holistic comments.

What I have said is very generic, but for a specific example, DTrace 
allows a sys-admin to view the per process I/O load on a system, 
something which was very hard to do on Solaris previously. The author of 
the iosnoop script, Brendan Gregg, has many other such scripts at [0]

I would look at the DTrace information available at Sun [1] before 
judging it based on an executive briefing done by Sales guys.

Kind Regards,

Nathan Dietsch

[0] http://users.tpg.com.au/adsln4yb/dtrace.html
[1] http://www.sun.com/bigadmin/content/dtrace/

>That's interesting about UFS+.  I've never heard of it.  I will do
>some reading on it - thanks for the note!
>
>  
>