Steve Shipway <[email protected]> wrote: > If your metrics are all coming in the same file, for the same point in time, > and all being pushed into the RRD at the same time, then it makes sense to > have a single RRD to hold them as in your example. You would usually use a > separate RRD if the data came separately, potentially for different times. > Then separate RRD would make sense as you may get one sample but not another, > or they were sampled at differing times.
To add to that, also consider how things may change over time. Eg, suppose you are logging disk/filesystem utilisation - both in terms of data transferred, and space used/available. It would make sense to collate all the quantities from one filesystem into a single RRD - so perhaps an RRD with bytes written, bytes read, % space used, $inodes used. But, a machine will almost certainly have multiple filesystems, and more importantly the number may change - so it would make sense to have one RRD/filesystem. Of course, there may well be more than one filesystem on a disk - so you might want to collect stats for the physical disk (probably just bytes read/written) into one RRD, and have a separate RRD for each physical disk (or array) since the number of physical disks/arrays may change (eg if you add a disk because you've run out of space). There isn't really a right and wrong. It's perfectly OK to have lots of small RRDs with a single DS each. It's also perfectly OK to have fewer RRDs with many DSs each. It's a matter of balancing your requirements with the ability to manage the RRDs - and of course, as mentioned above, the requirement to update all DSs in a single RRD at the same time. I tend to use a mixture. At one extreme I have an RRD for our UPS stats with many parameters logged, and another with 508 DSs (data in and out for all 254 usable addresses in our /24 subnet) - in both cases, data is collected and graphed with custom scripts, and all the data is collected in a single operation. At the other extreme, I have a whole bunch of RRDs with just 2 DSs (data in and out) - one per port for a bunch of switches (the data is collected and graphed with Cacti), and the data for each port is collected separately (it's the way Cacti works). _______________________________________________ rrd-users mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
