[rrd-users] Architecture independence for rrd files
s.shipway at auckland.ac.nz
Sun Jan 20 22:59:17 CET 2013
> I thought it would be a good idea on finding out how to make the rrd
> structure architecture independent, and if it's supposed to be, find
> out what's going on.
I believe Tobi is planning architecture-independence for the RRD file for RRDtool 2.x.
Making it arch-independent is not so easy (else it would have been done long ago as this has been on the cards some time). There are several problems relating to the generated C struct which is written to the file as created in memory:
1. endian - is it MSB first or LSB first (or middle byte first as in windows)
2. 23/64 bit - how big is an integer? This adjusts the size of the struct
3. alignment - does your architecture demand integers be byte-aligned and therefore generate padding bytes?
4. compiler peculiarities - some just do it differently at compile time.
The first is actively checked for by RRDTool (looking for different magic numbers in the header) and - I think - so is the second. Although it knows about them, though, working around it without losing a lot of efficiency would be a big problem.
It might be better to create a program to convert RRD files in one go (we can already do an XML export/import of course) though this too could be more trouble than it is worth.
I think there is more discussion on this in the Github area Tobi has set up https://github.com/oetiker/rrdtool-2.x
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