Restore of a small file or directory (e.g., only a few megabytes large) takes a long time from a large filesystem backup (e.g., a directory containing 1 terabyte of data).
Amanda stores filesystem backups in either of two general image formats:
Both formats restore by starting at the beginning of the image and streaming through it serially, whether you are restoring the entire image or only selected files/directories. Therefore, the time to restore files can be similar to the time it took to create the backup image.
For restoring only selected files, tar or the Zmanda Windows Client must still start stream through the entire image from beginning to end, restoring your files when it finds them.
To reduce the restore time for selected files, the backup time must be reduced. One way of doing this is to split it into multiple, smaller objects that back up different parts of the original, large object.
Consider the following example:
$ ls /big/data
Backup| What > Advanced Options > Alias
By splitting the large object into smaller ones and restoring from the smaller object, Amanda can stream through less data for the restore process.