One of the RAM disk that make up the ESXi host root file system might reach its resource pool limit as a result of a software failure or an accidental use of an incorrect path.
When an administrator manually copies files to the host and accidentally uses an incorrect path (that is, one outside /vmfs/volumes), this error message appears:
The ramdisk ‘root’ is full. As a result, the file /testfile could not be written.
Also, in the /var/log/vmkernel.log file, you may see the error:
VisorFSRam: 233: Cannot extend visorfs file /var/lib/vmware/hostd/journal/ because its ramdisk (root) is full.
Solution
SSH to the affected ESXi host
To view the ramdisk, run: $ vdf -h
Identify files in the root directory larger than 1 MB: $ find /var -size +1024k -exec du -h {} \; | less
Old/stale left over ESXi host log bundles should be copied/moved off and removed to provide space back to the ESXi host
remove file file is not required