[rrd-users] Changing RRA's while moving data to another platform

[Henrik Størner]

Hi,

I have a fairly large number of RRD-files that are used to collect 
various data related to performance on a system. Data collection happens 
every 5 minutes. All of the RRD's were created with this set of 4 RRA's:

# 5 min resolution = 1 PDP per CDP. 576 rows = 48 hours
RRA:AVERAGE:0.5:1:576
# 30 min resolution = 6 PDP's per CDP. 576 rows = 12 days
RRA:AVERAGE:0.5:6:576
# 2 hour resolution = 24 PDP's per CDP. 576 rows = 48 days
RRA:AVERAGE:0.5:24:576
# 1 day resolution = 288 PDP's per CDP. 576 days.
RRA:AVERAGE:0.5:288:576

The number "576" was chosen, because a 576 pixel graphic suited the 
then-common screen resolution of 800x600 just fine - I think this goes 
way back to the original MRTG resolution. But screens have gotten wider, 
storage capacity has increased, and users now would like to have more 
detailed data for a longer time.

I am about to mov the files from a 32-bit system to a 64-bit system, so 
it will be necessary to dump/restore all the files anyway. So this would 
be a good time to accomodate more detailed data. My plan is to grow each 
of the 4 RRA's like this:

# 14 days @ 5 min avg = 14*24*60/5 = 4032 rows
# (5/5)=1 PDP per CDP
RRA:AVERAGE:0.5:1:4032
# 90 days @ 30 min avg = 90*24*60/30 = 4320 rows
# (30/5)=6 PDP's per CDP
RRA:AVERAGE:0.5:6:4320
# 1 year @ 2 hour average = 365*24*60/(2*60) = 4380 rows
# (2*60/5)=24 PDP's per CDP
RRA:AVERAGE:0.5:24:4380
# 4 years @ 1 day average = (3*365+366)*24*60/(24*60) = 1461 rows
# (24*60/5)=288 PDP's per CDP
RRA:AVERAGE:0.5:288:1461

My question therefore is: What is the simplest (or quickest) way to do 
this ? Must I do an "rrd resize" for each of the RRA's, then dump, then 
restore the RRD file ? Or can it be done in one step ?

I know that it can be done with

    rrd resize foo.rrd 0 GROW 3456; mv resize.rrd foo.rrd
    rrd resize foo.rrd 1 GROW 3744; mv resize.rrd foo.rrd
    rrd resize foo.rrd 2 GROW 3804; mv resize.rrd foo.rrd
    rrd resize foo.rrd 3 GROW 885; mv resize.rrd foo.rrd
    rrd dump foo.rrd foo.xml

and then an "rrd restore foo.xml foo.rrd" on the new system, but it 
seems rather cumbersome when doing it for about 80000 files.


On a related note, is it possible to add an RRA at the same time ? E.g. 
if I would like to have a fifth RRA - say

# 30 days @ 15 min avg = 30*24*60/15 = 4320 rows
# (15/5)=3 PDP's per CDP
RRA:AVERAGE:0.5:3:2880

is it possible then to add that RRA somewhere during the process? I 
cannot see that any of the standard RRD tools will let you add another RRA.


Regards,
Henrik