On  2025-09-05  10:12, Thomas Lamprecht wrote:
Am 05.09.25 um 10:03 schrieb Aaron Lauterer:


On  2025-09-04  20:20, Thomas Lamprecht wrote:
Am 04.09.25 um 16:09 schrieb Aaron Lauterer:
this series does two things:
* switch the RRD API backend to use the old RRD files is available
* always use RRD files with the new 9.0 schema

The motivation for the combination of old and new RRD files is that during the
migration of old RRD files to the new ones, spikes get flattened. By combining
the old and new RRD files, we can keep the old coarse data with all it spikes
and only show the new much mode finer stepped data where available.

This will also enable us to just write any new data into an RRD file that is
created with the new 9.0 schema. As a result, no migration step is needed
anymore and we can simplify the logic around the whole "does the only the old
file exist or is the new one also present" alot in quite a few places.

Some examples which we can simplify or revert:
pve-manager: API2Tools::get_rrd_key can most likely be dropped
qemu-server, pve-storage, pve-container,…: rrd API endpoints which check which 
files exist
drop the whole migration step on upgrade

other TODOs:

RRD::create_rrd_graph -> see if we can combine both files into one graph. But we
are relying on RRD itself for this. So that might be interesting. On the other
hand, do we want to keep that API endpoint around? People are using it though.
So we need to weigh that decision accoringly.

Keeping it around for the time being is definitively required now that
PVE 9.0 is out, we might sunset it for a future major release.

Another option might be to generate both images and merge them manually,
i.e. literally make the right part the old and the left part the new
image with some imagemagick command. Or does rrd indeed supports merging
two files together?

One thing that should be possible is to give it two datasets from different 
files. That would be a middle ground as in, all data is there, but it would 
show up as separata data lines.

I am looking into it to see if we could get it nicer. Manually stitching images 
together will most likely not work because I don't expected the scales to match 
up perfectly.

True w.r.t. not matching scales. But as one can override the line colors we 
could probably just do that and use the same ones for both data series?

I did some prototyping and we can get both lines looking the same in the final graph directly from rrdtool graph.

I am now preparing a larger patch series, that also will include simplified/reverted changes now that we can count on the new pve-TYPE-9.0 rrd file to be present.


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