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When should I use storeByGroup?

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Is there a rule of thumb?
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asked Mar 12, 2014 by mfuhrmann (7,350 points)

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There is no rule of the thumb. StoreByGroup is more efficient in terms of disc-io then the default way. The only drawback is that it's a bit harder to see all the data-tracks that are collected. That might also effect your ability to remove a single one. But for the majority of cases store by group is the way to go.
answered Mar 13, 2014 by DerTak (5,420 points)
selected Mar 13, 2014 by mfuhrmann
Grouping all measured metrics in one RRD/JRB file reduces the amount of disk I/O. You need less file seeks, open and close operations for the reason you simply reduce the amount of RRD/JRB files and write more metrics in one big file. The price you pay for this setup is less the problem figuring out the data-tracks. The much bigger drawback is, if you add another metric to the data collection group, you have to recreate the RRD/JRB files for the whole metric group and you loose data even for all the other metrics you have already collected. I would only turn on StoreByGroup if you really really have no other option to increase your I/O performance in your system. You pay for performance with flexibility.