Device viewer indicates that the system drive has approximately 88 GB free out of approximately 467 GB, ~81% of the disk is in use. The size of the root directory (/root) is 79 GB; VirtualBox files contribute to this size.
Running the du command, I see that various mounted local drives located under the directory /z supposedly occupy 839 GB:
You probably mean “the root directory (/)”. /root is something different.
using du is not very usefull to find out how large file systems are and how full they are. Better
When you mount something, where it is mounted from has no influence on what is already mounted.
Mounting in /z or /mnt ot wherever is basicaly the same. Using /mnt is only a convention. And for permanent usage deciding your own place in the directory tree (like you did with /z) is fine, it keeps /mnt free for e.g temporary usage or tests.
The directory /root has nothing to do with your problem. It is the home directory of user root. It is not a mount point. Mentioning it is at the minimum confusing.
When the command df -h tells the same as the “device viewer” then let us forget the device viewer and concentrate on the easier to produce and read CLI.
Most probably the root partition (sde2) is a btrfs file system. For btrfs df does not give trustworthy results. There is a special btrfs command that shows how much is free on a btrfs file system. Sorry, I do not use btrfs can not produce that command (I tried browsing through the man pages, but could not find it).
The file system on the system in question is linux-5 is Ext4; the other machine (linux-3) is using BtrFS. (I’ve stopped using BtrFS on new installs.)
I still trying to determine how much free space I have on sde2. 88 GB or 377 GB (467 less the ~90 GB I mentioned in my last post).
I don’t understand why mounting “blocks” the difference. I note that df -h has several columns including: Size, Used, and Avail. I also don’t fully understand meaning of the entry in the Used column and why the number is not considerably smaller.
What is driving these questions is a new PC, where I wish to set up a very similar configuration, but now with 15.3. The new PC has two drives about the same size as sde on linux-5 (marketed as 480 and 500 GB, respectively).
Given the 81% usage figure for sde2, should I install a 1TB drive to provide some breathing room? Or, can I safely use the ~500 GB drive?
Please note - data will be stored elsewhere; just OS and applications. Therefore, the new installation should not be appreciably larger - perhaps smaller since I plan to locate the VirtualBox vdi files (~75-80 GB) on a separate drive.
I have not been following this thread very closely.
Why you are using that much space depends on what you are doing. You mention VirtualBox. I’m using KVM for virtualization, but I have my VM images stored in a different partition (using symbolic links). If I were to put those in the root file system, I would need a lot more space.
Note the device name on the latter. That disk currently has 23 Linux distro installations, each on a 6.2G filesystem, and 82GB in unallocated disk space for more partitions. Stuff accumulates according to the space available for it to fill. Small disks get backed up and restored faster, thus it’s easier to do backups often enough to risk little.