VM Ubuntu: What are /dev/mapper and /dev/sd1?

I want to increase the free disk space of my VM Ubuntu (host = Mac 10.10). After autoclean -> auto remove, I still 80% (=5.7/7.5 GB)of space used in /dev/mapper, however, only 3% (=7.2/246.8 MB) used in /dev/sda1.

Could anyone explain me what are /dev/mapper and /dev/sda1, and their relation with the base memory (=2000MB) of my VM? And how to even increase the free space?

Thank you for any help!

Solution 1:

Altough this doesn't fully address the question, in order to free up some space I suggest you to first remove the installed packages that are not needed anymore:

sudo apt-get autoremove --purge

Then you can clear the /var/log folder, which is extremely prone to grow in size over time, expecially if something at some point didn't work perfectly:

sudo rm -rf /var/log/*

Then you can use this command to list all your files/folders sorted from the smallest file/folder to the biggest file/folder, in order to quickly spot which files/folders are the biggest so you can possibly free up some additional space:

du -ahd <n> / | sort -hr

Where <n> is a number higher or equal to 0 representing the depth of the search.

3 should be a number large enough to narrow down the search a bit without having to deal with an excessively large list of files/folders.

Solution 2:

Probably /dev/sda1 is a small conventional boot partition, while /dev/mapper contains a LVM2 logical volume consisting of the remainder of the filesystem as a single root LV, which would be the normal configuration if you had selected the "Use entire diskwith LVM" option during installation. For instance, my current (non virtual) installation has

/dev/mapper/ubuntu--vg-root  162G   14G  140G   9% /
/dev/sda1                    236M   66M  158M  30% /boot

You would need to provide additional information in your question (such as the output of the command df -h | grep ^/) for anyone to know for sure. To increase the free space you would need to remove additional installed software or unneeded data.