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c : 6 May 2007 • 9:32AM -0400

[cricket-developers] JustInTimeRRD patch
by Kevin Stewart


I have just created a patch to cricket to allow one of my servers to
collect 30000 targets across 900 hosts and thought others might be
I am using a duel Xeon with 4Gig of RAM 2 SCSI disks striped
My 30000 targets create 14Gig of RRDs
I am using 40collectors to allow collection within 4.5 Min
I copy parts of the tree to create 40 config trees and use the base:
option to change the configtree base for collect-subtrees and have 40
subtreeset files
that was stage one....
all would run fine till creation of the 2 hourly averages where the
system would jump to 70% IO wait and load 80
collection time would jump to 10-15 min
all due to lack of update locality in the RRDs (more RAM ... 14+ Gig
would help but thats not the point)

hence my idea and this patch
get collector to update CSV files and update the RRDs in batches every
hour and get grapher to update the RRDs before it graphs them
as all the graphs are not looked at all the time this would have little
impact on the system
all that is needed is a setUID perl util to update the RRD from the CSV
and a cron job to run that job every hour or so.
Now I will return the RAM I borrowed and drop the system back to 2Gig
and it should continue to hum

I would like to change this patch so I can have the CSVs and RRDs in
different trees so I can have them stored on different boxes and NFS
mounted but that is for another day
I would like some suggestions should the location be in the database or
the config file

below is a link to graphs of an example collection time graph and a load
graph for the system. be nice they are on my ADSL connection

I implemented the change on this server Friday 15:15 you may be able to
see the difference


Shameful plug
If you are still reading you may like to look at TILT (Terminal
Interaction Logging Tool)
It logs tty sessions (SSH telnet bash) and allows playback (realtime or
not) and searching via regexp with timestamps on every line if needed
I use it so I can find what I did when and how I did it
try it and tell me if you like it or even if you don't

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