[rrd-users] Re: Better many .rrd files vs. many DSs per file ?

[Alex van den Bogaerdt]

On Tue, Nov 14, 2006 at 10:51:50AM -0800, Lancashire, Pete wrote:

> I will be doing some performance testing and will need to update
> 176 DS's at least every 10 seconds, maybe every 2 seconds at a
> time.

> The rrdtool executable will be on another machine interface will
> be with rrdsrv.

I can't comment on this, except that I can guess the network will
probably be faster than writing to disk (thus not a bottleneck).

> I'm going to put my rrd files on a dedicated SCSI raid0 array with
> 6-10 spindles to help with writes, O/S will be Linux.
> 
> The DS are in 4 'groups'
> 
>   group      #DSs
>   cpu total   20
>   cpu         48
>   disks       90
>   network     18

Are you going to update all "cpu total" at the same time, and all
"cpu" at the same time, or are you going to update
server1{cpu0,cpu1,cpu total} at the same time,
server2{cpu0,cpu1,cpu total} at the same time, and so on?

This is quite important to know.

> If this all works for one server, I will want to do it for the
> 4 servers in my cluster so the number of DS could go over 700.

You have four servers now.  This may increase to for instance eight.
It seems to make sense to use a separate rrd file for each server.

And you may currently have 'n' network cards per server, but this
may also change in the future. Perhaps you also want to take this
in consideration.


The most flexible would be each DS in its own file.  This will
also use the most resources.  It may not be a problem for your
hardware.

If you combine DSes in one RRD file, you will want to do so with
DSes that you can update at the same time -and- you want to be
reasonably sure that you won't need more DSes in that file.

HTH
-- 
Alex van den Bogaerdt
http://www.vandenbogaerdt.nl/rrdtool/

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