I did a reinstall from scratch to go from omv 0.5 to 1.0. I reconfigured everything, no issues so far, it went quite smoothly.
I wanted to keep RRD records. I managed to backup then restore the RRD records but had to do some manipulation with the df RRD records because the format changed between 0.5 and 1.0.
For some reason, after I restored my RRD records, the free space for my data volume is not identical to previous omv version (while used space remains the same). See screenshot below to illustrate:
I doubt this is an RRD issue as I did not change any data, I'm thinking more about something like space reservation which used some free space.
Does anyone has some explaination to this?