by Ken Task.
What does php -v show? 32 bit version of PHP? If so, operating system can't work with files over 2 gigs if I re-call correctly (happened on Windows - not on linux 64 bit servers).
What you are looking at in the Moodle UI is data coming from DB. In this case, the table mdl_files has file information (meta data) that includes file size.
Use the following MySQL query:
select contenthash,filename,filesize from `mdl_files` where (`filearea` like "backup" and `filename` like "%.mbz%")
The output of that will show something like - last column is size.
| c3e4ba471441b6cd9572caa1f774f52f99eca66c | backup-moodle2-course-261-soc-20131220-1236-nu.mbz | 3344134 |
The first column is the content hash and shows the physical location of the file.
moodledata/filedir/c3/e4/c3e4ba471441b6cd9572caa1f774f52f99eca66c
Use whatever you have to browse files to see the file size. No files by humanly recognizable names in vr. 2 or higher.
The neg number certainly not coming from operating system (I would hope) - it's meta data from DB.
That's an autobackup that probably failed.
So, you could delete that row in mdl_files as well as any file that might reside at the location you find in moodledata/filedir/xx/xx/contenthashname
For failed backups ... any files/folders remaining in moodledata/temp/backup/ can also be removed manually with no ill affects.
If you run automated backups, suggest saving them to a designated directory that you create. Makes it easier to find those backups by humanly recognizable names then.
Might be more stuff we need to look at or locate, but for now ....
'spirit of sharing', Ken