Re: [hobbit] hobbitclient on solaris: using iostat for cpu stat

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

Hi Gianluca,

On Thu, Dec 01, 2005 at 02:28:09PM +0100, Gianluca Rossi wrote:
> Hi Henrik,
> I have seen that hobbit clients collects cpu stats via vmstat, now i 
> think that the cpu information provided by "iostat -c" is more accurate, 
> because it has the "%waiting for i/o" columns, wich is also in the linux 
> version of vmstat.
> do you think you can add this information?

this was a surprise. I didn't know that iostat's CPU statistics was more
detailed than vmstat's.

I have updated the Solaris Hobbit client so it collects the CPU
statistics, through a "iostat -c 300 2" command like it does with
vmstat. However, changing Hobbit to pick up the I/O wait data is 
problematic, because the vmstat RRD file for Solaris systems doesn't
have this dataset defined. So to use these data, I need to change the
layout of the Solaris vmstat RRD - which means you will lose all of
the statistics collected until now. This was a bad mistake I made when
I first decided on the vmstat layout - I should have made it identical
across OS'es, instead of sticking with the old LARRD layout where it was
different for each OS. (netstat had the same issue, and there I decided
to use a common format).

I can make Hobbit work with a new format, but it will require some more
code - so I'll postpone this until after 4.2 is out.

While looking at iostat, I also dug into the disk statistics it can
provide. I have never managed to get any meaningful data from the old
BB iostat script, so let's do this properly for Hobbit. So far, the
client will collect the data - analysing them and doing the graphs comes
later.


Regards,
Henrik