Re: [hobbit] TCP/IP stats (bits/s) limited to 100M

[henrik (at) hswn.dk (Henrik Stoerner)]

On Wed, Jun 28, 2006 at 04:07:44PM +0200, Nicolas Dorfsman wrote:
> >The RRD files are created as "DERIVE" datatypes with a minimum  
> >value of
> >0, which should handle 32/64-bit counter overflows automatically.
> >(See the rrdcreate man-page).
> 
> Well...the man is not so confident :
> 
>                      If you cannot tolerate ever mistaking the
>                      occasional counter reset for a legitimate
>                      counter wrap, and would prefer "Unknowns"
>                      for all legitimate counter wraps and resets,
>                      always use DERIVE with min=0. Otherwise,
>                      using COUNTER with a suitable max will
>                      return correct values for all legitimate
>                      counter wraps, mark some counter resets as
>                      "Unknown", but can mistake some counter
>                      resets for a legitimate counter wrap.

OK, you got me on that one.

It seems that using COUNTER for the byte-counts in both the
netstat- and ifstat-RRD's might be a good idea. The question then
becomes "what's a suitable max" for these data ? Should I 
assume they are 32-bit counters ? I know some of them are not
(e.g. Solaris has 64-bit counters for bytes in/out per interface).

I'll change it to a counter now, with MAX set to "unknown". The overflow
handling should still work correctly, if I understand the RRD
docs right.

Note: This doesn't affect all of the existing RRD's, only new ones 
created.


Regards,
Henrik