When I run blkid I get
/dev/vda1 ...etc
/dev/vda2 ...etc
However, when I run df -h I do not see the second drive. I only see
/dev/vda1 ...etc
/devtmpfs ...etc
Is this because df only shows file systems that are mounted, and the vda2 drive is not mounted? Can you help me understand the difference between the two and why df -h doesnt show the second drive vda2 ?
From the relevant man pages:
"blkid - locate/print block device attributes"
"df - report file system disk space usage"
So df tells you about disk space usage of the filesystems on those block devices.
In response to your supplementary comments on your question, it's not that either is "best" per se, they are different tools.
In short
df shows the mounted file systems and details about themblkid shows the block devices (drives, partitions) that are found and details about themlsblk can give you a good overview of both
sudo lsblk -fm # in a wide terminal window
or, if your terminal window is not wide enough, for example only 80 columns
sudo lsblk -f
sudo lsblk -m
or, if you want to skip some details,
sudo lsblk -o model,name,size,fstype,label,mountpoint
dfshows only mounted file systems; 2. Different tools are 'best' for different purposes, maybe you will findlsblkbest for this particular purpose (to list all file systems and show if they are mounted). It will show all drives and partitions, not only those with file systems, but also a swap partition, an extended partition, and a partition that is not yet formatted.