Startup drive filled with "other" category

[jbaugh]

I am running Mac OS 10.15.5 on my iMac with a 500GB SSD internal startup drive. When I try to copy a large file to the drive I get a warning that there is not enough space on the drive to do the task. "Get info" shows that there are only 36GB of space available on the drive with the remaining 436GB used. Under "About this Mac/Storage" the same information is reported. It shows that the vast majority of the drive (362GB) is used by the "other" category. Despite exhaustive search I cannot find what accounts for this 362GB of used disk space.

Interestingly, if I do a bootable clone of my SSD startup drive with Carbon Copy Cloner, the drive only uses 147GB of disk space. If I boot from this cloned drive the "other" category essentially disappears and my drive is shown to use only the 147GB.

What accounts for the huge loss of disk space on my SSD? How do I reclaim this space? I am tempted to just restore my SSD from the cloned drive but I'm not sure that is wise.

Any ideas will be greatly appreciated.
John

 

[jbaugh]

It turns out that for some reasons my Mac was holding on to large numbers of TMAchine snapshots that were eating up large amounts of disk space. When I deleted these snapshots I regained most of the unaccounted for disk space. But there are still about 40 GB of space I still can't account for. When I deleted the snapshots most of the disk space was recovered.