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:
- UNIX/Linux filesystem, NFS, and CIFS backups are
tararchives, usually GNU tar.
- Windows NTFS backups are based on the
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 dir1/ dir2/ largedir1/ largedir2/ file1 file2
- Create a backup object for ”
/big/data” and exclude the large subdirectories (“
./largedir1” and ”
./largedir2“). Please see the following documentation for details about exclude syntax:
- Back up each sub-directory as a separate object:
- Or (UNIX/Linux, NFS, and CIFS only) create multiple /big/data backup objects with different aliases (
Backup| What > Advanced Options > Alias), and use
excludeproperty can be set in
Backup| What, but the
includeproperty must be manually added to the “
/etc/amanda/<BackupSet>/disklist.conf” file. Please see the following article for more information:
By splitting the large object into smaller ones and restoring from the smaller object, Amanda can stream through less data for the restore process.