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[chrismd <question170794@xxxxxxxxxxxxxxxxxxxxx>]

Question #170794 on Graphite changed:
https://answers.launchpad.net/graphite/+question/170794

    Status: Open => Answered

chrismd proposed the following answer:
The problem definitely appears to be related to the high I/O utilization
as there is no CPU bottleneck, the incoming metrics vastly exceeds the
datapoints getting written to disk, and the cache is completely full
(hence all the gaps in the graphs). What does your I/O utilization look
like with no carbon daemons running? (hopefully around 0% when measured
over a 60-second interval). If you set MAX_UPDATES_PER_SECOND to 50 then
carbon should be doing very little I/O work, so maybe some other process
on the machine is generating this I/O load?

Also how much ram do you have? A huge piece of the performance puzzle
for graphite is having enough ram for the kernel to buffer writes. If
you have too little ram or other processes on the machine eating it up
that could cause problems like this. It may be beneficial to run an I/O
benchmark like bonnie to make sure the system is setup for optimal
performance.

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