Reasons for not using storage entirely?
I inherited a server and cannot reach the previous admin. At this time I need more space and plan to resize the image to take up unused space in the linode (CentOS 7, Linode 2GB: 1 CPU, 50GB Storage, 2GB RAM). But I'm curious why it was set up this way in the first place. Current configuration:
25600 MB Used
25600 MB Available
50% of your 51200MB is allocated towards 2 disk images.
CentOS 7 Disk ext4 25088 MB
512 MB Swap Imag swap 512 MB
df -h Filesystem Size Used Avail Use% Mounted on devtmpfs 909M 0 909M 0% /dev tmpfs 920M 0 920M 0% /dev/shm tmpfs 920M 97M 823M 11% /run tmpfs 920M 0 920M 0% /sys/fs/cgroup /dev/sda 24G 22G 2.0G 92% / tmpfs 184M 0 184M 0% /run/user/1003
I'm particularly curious about the part, above, that says "is allocated towards 2 disk images" because I'm only aware of one, and nothing is listed in the Linode admin interface section labeled "Images."
Linode Images aren't the same as the disks setup in a linode.
That section in the UI you are looking at is about these: https://www.linode.com/docs/platform/disk-images/linode-images/
You list the two disks in your post - one is the ext4 disk 'CentOS7 Disk', the other is the 512MB swap. You've got about half of your storage for that linode used with those two disks. You can expand either disk, or add another disk that you mount elsewhere.
The big reason to not use up all the space available is to keep the disk small for things like migrations and resizes. If you need the space (and at 92% used, I'm assuming you do), by all means extend the volume. Here's how:
I had a whole writeup I was about to post, but @millisa provided most of what I was going to provide.
The only thing I wanted to add was some historical context, as this was a common question we saw when we increased storage capacity on Linode plans. Since you inherited the Linode, it's likely the Linode was from before this increase. When an upgrade was done to the Linode, if the resize disk option wasn't selected, the additional storage would not have been allocated to those disks. We've since enabled this to be done all at the same time.
Cloud-based storage systems such as Dropbox or Google Drive can save you time and disk space, but enable tracking with ease. Store files on a own hard disk, rather than cloud, to help reduce the possibility of accessing data from third parties. https://finestediting.com/services/business-proofreading.php