[rrd-users] Re: I know this is repetitive... but, is there a way to add a new DS to

Przemyslaw Karwasiecki karwas at ifxcorp.com
Tue Jun 25 23:33:06 MEST 2002

On Tue, 2002-06-25 at 17:10, Hamish Marson wrote:
> Firstly, why do you assume that all data is cololected by SNMP? The bulk 
> of mine is collected from a logfile (Postfix & amavisd logs)

You are absolutely correct.

I just happen to know how Francisco (author of an original post)
is collecting data, as we work for the same company, although 
in different countries....

Nevertheless, your point is absolutly valid:
not every application is using SNMP for data collection.

> >
> >Any comments?
> >
> A couple.
> 1. I'm not & others aren't using snmp. There is far more data to be 
> processed that isn't snmp than is.
> 2. Not everyone has hardware that's capable of updating 1300 files in 
> just a second or so.
> 3. When you perform the rrd update is NOT irrelevent if the update time 
> is short. If yuou update once an hour, you have plenty of time. Every 10 
> seconds or even every minutes, and it gets a little more critical.
> YMMV of course... Which is a point I made.

I was just pointing that actual time of RRD update operation
is not the same as time stamp of data. 
So if update is delayed, your data doesn't necessarily needs 
to be skewed.

But your point that you will not be able to cope with massive
number of updates, if you do plenty of them very often, is valid.

I was biased by my 5 minutes interval with origins in MRTG....


> You add new DS's perhaps once a month or once a week at the most? No 
> need for much optimisation there. It doesn't actually require an XMP 
> dump to do either, if you know the binary format of the file...

True again. In my specific case it is simply easier to manage multiple
small RRDs, then couple of big RRDs with multiple DSes....

And, also in m case, I can afford multiple updates simply because
I have relatively low frequency update.


> As it should be since it's the most ofthen used task. remember though 
> with lots of files, just the open alone requires a linear search through 
> the directory structure... That's a fair wack of IO just there...

Two questions here: directory is a linear structure on disk -- true,
but are you sure that once it is loaded (cached) to memory,
(no more IO needed!), it is not hashed somehow to speed up lookups?

As far as my hardware -- it is pretty standard, P700 Linux 2.4 with 
ext3fs on IDE drive.



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