Hi Wu Yaping,
Try running tabadmin cleanup would help. This clears out old log files, and may free up some space. Try running tabadmin cleanup first, then tabadmin backup again. If that doesn't help, try specifying a different temp directory (with much more disk space) for the creation of the backup. This can be done using the "-t" flag in the tabadmin backup command, followed by the path you want to use. Here's an example: tabadmin backup newbackup -t D:\BiggerDrive\Tableau
Thanks & Regards,
I already know the reason for this problem. The tabadmin cleanup was executed during the backup,which is triggered by a scheduled task.
Thanks a lot.