The temporary directory is used for various purposes, such as storage of temporary spooled file (for database specific backup type in %edition_name%), remote file list, local file list, temporary delta file and other files of temporary nature.
For database backup in %edition_name% such as MySQL, MariaDB, Oracle, MS SQL Server (ODBC backup mode) , and Lotus Domino, it is highly recommended that the temporary directory or volume used for these modules is a local drive (not a system volume e.g. not the same partition which the operating system is installed on). If the temporary directory is located on a network drive it may affect the backup performance.
Also sufficient disk space must be allocated for the temporary directory, and the formula of calculation of disk space is as following:
(Total File Size * Delta Ratio) * number of backup destinations = Maximum Free Space Required
For example: An Oracle database backup
If the default Delta ratio is 50% for in-file delta, and if the total Oracle database size is 1TB and there is only one backup destination, the minimum free space needed on the drive where the temporary directory folder is located = 1.5TB.
*1TB = Total Oracle database size
*500GB = Total maximum size of incremental or differential delta files generated
Administrators need to pay attention to the maximum file size limitation of different file system format, so that database file can be spooled to the temporary directory.
It is strongly suggested to use local drive instead of network drive to ensure optimal backup/restore performance.