New SSD - Possibility to change partitions/filesystem

[SeverusM]

Hi,
Might be a weird and a bit complicated question. I currently only have a 500GB SSD and want to move to a new 1TB one, but I don’t want to do a new installation, but copy everything over using Rsync using the technique of a system backup I found in the Arch Wiki. My installation is around 6 years old, switched from antergos to endeavour during that time.
Not quite sure, if it allows for my goals to complete the way I want to though. So I’m asking here. I’ve been researching like crazy, but don’t come to a conclusion.

I currently have 4 partitions and using ext4 as a filesystem, besides /boot of course.
Partitions are /boot, /root, /var and /home.

With this move I hope to be able to switch to btrfs though and only have 3 partitions, as I’ve found sepearating /root and /var has been an error and caused a few irritations during the years. I’d like to have them as one again, so that I only have /root and /home in addition to /boot.

Will it be possible to reintegrate /root and /var into one partition? How can I archieve it when copying over everything with rsync? Is it fine switching to btrfs on the new SSD?

I currently have the old SSD still in the PC and have the new SSD in an external housing connected via USB and just hope to switch, when everything works.

[BluishHumility]

@SeverusM

Will it be possible to reintegrate /root and /var into one partition?

If you are switching to Btrfs, I would put everything together on one partition–including /home and /boot–and separate things with subvolumes instead of partitions. That way you don’t split the disk into multiple Btrfs filesystems, and additionally will give you more flexibility with the size of any given subvolume than cutting the disks into partitions will (you don’t have to worry about /boot becoming full unless the whole disk is full, for example).

@SeverusM

How can I archieve it when copying over everything with rsync?

No special consideration is needed to accomplish this with rsync. Just point rsync to wherever the directories are meant to go on the filesystem and it will bring the files over. rsync does not care about the partitions you have or don’t have.